Human milk oligosaccharides(HMOs)are one of the major differences between livestock milk and human milk,and the prebiotic functions of HMOs have been verified through in vitro and clinical trials.The most abundant HMO...Human milk oligosaccharides(HMOs)are one of the major differences between livestock milk and human milk,and the prebiotic functions of HMOs have been verified through in vitro and clinical trials.The most abundant HMOs include 2′-fucysollactose(2′-FL),3-fucosyllactose(3-FL),lacto-N-neotetraose(LNnT)and lacto-N-tetraose(LNT);their application and synthesis have attracted wide attentions.In recent years,the biotechnological production of 2′-FL,3-FL,LNnT and LNT have emerged based on techniques such as whole-cell catalysis and fermentation.In particular,the development of metabolic engineering and synthetic biology methods and strategies have facilitated efficient biosynthesis of these HMOs.However,these advantages have not been systematically reviewed yet.In this review,we first discuss the structures and applications of HMOs;secondly,strategies of microbial synthesis of the most abundant 2′-FL,3-FL,LNnT and LNT are summarized and compared.Finally,challenges and perspectives of efficient microbial production of HMOs as well as strategies for overcoming the challenges are discussed.This review reveals the whole picture of recent development in HMOs microbial synthesis and can further facilitate the understanding of limiting factors,and further propose a few directions to promote the development of efficient production hosts.展开更多
Plants and microbes are closely associated with each other in their ecological niches.Much has been studied about plant-microbe interactions,but little is known about the effect of phytochemicals on microbes at the mo...Plants and microbes are closely associated with each other in their ecological niches.Much has been studied about plant-microbe interactions,but little is known about the effect of phytochemicals on microbes at the molecular level.To access the products of cryptic biosynthetic gene clusters in bacteria,we incorporated an organic extract of hibiscus flowers into the culture media of different Actinobacteria isolated from plant rhizospheres.This approach led to the production of broad-spectrum dithiolopyrrolone(DTP)antibiotics,thiolutin(1)and aureothricin(2),by Streptomyces sp.MBN2-2.The compounds from the hibiscus extract responsible for triggering the production of these two DTPs were found to be hibiscus acid dimethyl ester(3)and hydroxycitric acid 1,3-dimethyl ester(4).It was subsequently found that the addition of either Fe2+or Fe3+to culture media induced the production of 1 and 2.The Chrome Azurol S(CAS)assay revealed that 3 and 4 can chelate iron,and therefore,the mechanism leading to the production of thiolutin and aureothricin appears to be related to changes in iron concentration levels.This work supports the idea that phytochemicals can be used to activate the production of cryptic microbial biosynthetic gene clusters and further understand plant-microbe interactions.展开更多
The effects of feed strength, hydraulic residence time （HRT）, and operational temperatures on soluble microbial product （SMP） production were investigated, to gain insights into the production mechanism. A carrier...The effects of feed strength, hydraulic residence time （HRT）, and operational temperatures on soluble microbial product （SMP） production were investigated, to gain insights into the production mechanism. A carrier anaerobic baffled reactor （CABR） treating dilute wastewater was operated under a wide range of operational conditions, namely, feed strengths of 300-600 mg/L, HRTs of 9- 18 h, and temperatures of 10-28℃. Generally, SMP production increased with increasing feed strength and decreasing temperature. At high temperature （28℃）, SMP production increased with decreasing HRT. As the temperature was decreased to 18 and 10℃, the SMP production was at its peak for 12 h HRT. Therefore, temperature could be an important determinant of SMP production along with HRT. A higher SMP to soluble chemical oxygen demand （SCOD） ratio was found at high temperature and long HRT because of complete volatile fatty acid degradation. SMP accounted for 50%-75% of the SCOD in the last chamber of the CABR. As a secondary metabolite, some SMP could be consumed at lower feed strength.展开更多
The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon ...The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon （BAC） was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket （UASB） reactors. The high strength organics were degraded in the first UASB reactor （UASB1） and the second UASB （UASB2, i.e., BAC） functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand （COD） was 10,000 mg/L and the organic loading rate achieved 10 kg COD/（m 3 ·day）, the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.展开更多
Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products （SMP） during drinking water biofiltration. Four pilot-scale biofilters with ceramsite as the medium...Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products （SMP） during drinking water biofiltration. Four pilot-scale biofilters with ceramsite as the medium were fed with different acetate loadings for the determination of SMP formation. Using numerically simulated and measured parameters, the theoretical model was developed according to the substrate and biomass balance. The results of this model matched the measured data better for higher SMP formation but did not fit well when SMP formation was lower. In order to better simulate the reality and overcome the difficulties of measuring the kinetic parameters, a simpler empirical model was also developed. In this model, SMP formation was expressed as a function of fed organic loadings and the depth of the medium, and a much better fit was obtained.展开更多
A two-phase anaerobic reactor fed with glucose substrate（3 g chemical oxygen demand（COD）/L） was used to investigate the effects of toxic metals on the degradation of organics and the soluble microbial product（SMP...A two-phase anaerobic reactor fed with glucose substrate（3 g chemical oxygen demand（COD）/L） was used to investigate the effects of toxic metals on the degradation of organics and the soluble microbial product（SMP） formation. Low concentrations of Ni（II）（5 and10 mg/L） promoted the acid phase, whereas high concentrations（15, 20, and 25 mg/L）exhibited an inhibitory effect on, but did not alter the fermentative method, which mainly involved the fermentation of propionic acid. The methanogenic microorganism exhibited a strong capability adapting constantly increased Ni（II） levels. The acid phase was an accumulation stage of SMP. In the absence of Ni（II）, the high-molecular-weight material in the effluent SMP mainly contained polysaccharide, tryptophan, and casein. Methanogens metabolized most of the polysaccharide, the whole tryptophan content, and part of the casein, leading to the presence of humic acid and protein in effluent. After Ni（II） dosage, the protein and polysaccharide of the acid phase increased, and tryptophan changed, while casein remained stable. More protein than polysaccharide was produced, suggesting the prominent function of protein when addressing the negative effect of toxic metals. The analysis of DNA confirmed the change of bacterial activity.展开更多
[Objectives]The paper was to study the toxicity of 9 biocontrol microbial products to adult population of Lasioderrma serricorne.[Methods]Nine biocontrol microbes were used as test materials to study their toxicity to...[Objectives]The paper was to study the toxicity of 9 biocontrol microbial products to adult population of Lasioderrma serricorne.[Methods]Nine biocontrol microbes were used as test materials to study their toxicity to the experimental population of L.serricorne adults.[Results]The toxicities of these biocontrol microbes from low to high at 5 d post spraying were:Luhai Beauveria bassiana powder(LC_(50)=462.752×10^(8) spores/L),Meichongzhi B.bassiana powder(LC_(50)=9713.157×10^(8) spores/L),Yiqiang Bio B.bassiana powder(LC_(50)=11203.321×10^(8)spores/L),Nongbao Bio B.bassiana powder(LC_(50)=12188.866×10^(8) spores/L),Yeshengwang B.bassiana powder(LC_(50)=21685.532×10^(8) spores/L);Fatu Bacillus thuringiensis suspension(LC_(50)=1.0844×10^(8) IU/L),Laojite B.thuringiensis suspension(LC_(50)=2.056×10^(8) IU/L),Lujinwa B.thuringiensis powder(LC_(50)=2.273×10^(8) IU/L),Nongbao Bio B.thuringiensis powder(LC_(50)=18.399×10^(8) spores/L).The toxicities of these biocontrol microbes from low to high at 10 d post spraying were:Nongbao Bio B.bassiana powder(LC_(50)=0.072×10^(8) spores/L),Yiqiang Bio B.bassiana powder(LC_(50)=2.484×10^(8) spores/L),Luhai B.bassiana powder(LC_(50)=44.551×10^(8) spores/L),Meichongzhi B.bassiana powder(LC_(50)=96.447×10^(8) spores/L),Yeshengwang B.bassiana powder(LC_(50)=723.347×10^(8) spores/L);Lujinwa B.thuringiensis powder(LC_(50)=0.0001×10^(8) IU/L),Fatu B.thuringiensis suspension(LC_(50)=0.045×10^(8) IU/L),Laojite B.thuringiensis suspension(LC_(50)=0.0644×10^(8) IU/L),Nongbao Bio B.thuringiensis powder(LC_(50)=1.899×10^(8) spores/L).The toxicities of these biocontrol microbes from low to high at 15 d post spraying were:Meichongzhi B.bassiana powder(LC_(50)=0.001×10^(8) spores/L),Nongbao Bio B.bassiana powder(LC_(50)=0.01×10^(8) spores/L),Yiqiang Bio B.bassiana powder(LC_(50)=0.084×10^(8) spores/L),Luhai B.bassiana powder(LC_(50)=2.370×10^(8) spores/L),Yeshengwang B.bassiana powder(LC_(50)=8.915×10^(8)spores/L);Lujinwa B.thuringiensis powder(LC_(50)=0.16×10^(4) IU/L),Laojite B.thuringiensis suspension(LC_(50)=0.185×10^(4) IU/L),Fatu B.thuringiensis suspension(LC_(50)=32.211×10^(4) IU/L),Nongbao Bio B.thuringiensis powder(LC_(50)=1590×10^(4) spores/L).[Conclusions]According to the three stages of tube rubbing,it is found that the control effects of Lujinwa B.thuringiensis powder and Meichongzhi B.bassiana powder are the best,and the results will provide technical support for the biological control of L.serricorne adults.展开更多
Soluble microbial products(SMPs),dissolved organic matter excreted by activated sludge,can interact with antibiotics in wastewater and natural water bodies.Interactions between SMPs and antibiotics can influence antib...Soluble microbial products(SMPs),dissolved organic matter excreted by activated sludge,can interact with antibiotics in wastewater and natural water bodies.Interactions between SMPs and antibiotics can influence antibiotic migration,transformation,and toxicity but the mechanisms involved in such interactions are not fully understood.In this study,integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic,trimethoprim(TMP),which has a low biodegradation rate and has been detected in wastewater.The results of liquid chromatography-organic carbon detection-organic nitrogen detection indicated that the SMPs used in the study contained 15% biopolymers and 28% humic-like substances(based on the total dissolved organic carbon concentration)so would have contained sites that could interact with TMP.A linear relationship of fluorescent intensities of tryptophan protein-like substances in SMP was observed(R^(2)>0.99),indicating that the fluorescence enhancement between SMP and TMP occurred.Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that carboxyl,carbonyl,and hydroxyl groups were the main functional groups involved in the interactions.The electrostatic andπ-πinteractions were discovered by the UV-vis spectra and 1H nuclear magnetic resonance spectra.Structural representations of the interactions between representative SMP subcomponents and TMP were calculated using density functional theory,and the results confirmed the conclusions drawn from the 1H nuclear magnetic resonance spectra.The results help characterize SMP–TMP complexes and will help understand antibiotic transformations in wastewater treatment plants and aquatic environments.展开更多
In order to promote the transformation and high-quality development of strawberry industry and speed up the application of functional microbial products in strawberry,the application technology of functional microbial...In order to promote the transformation and high-quality development of strawberry industry and speed up the application of functional microbial products in strawberry,the application technology of functional microbial products in strawberry planting is studied and summarized.It mainly includes:the periods and methods of continuous cropping strawberry soil reduction and disinfection at high temperature,before and after strawberry planting,before plastic film mulching and whole process of plant spraying.Through multi-point test and demonstration,the purpose of advancing the season of strawberries,improving the quality,increasing production and increasing efficiency is achieved,and there is no risk of agricultural residue pollution,which meets the needs of people's consumption upgrading.Therefore,the application of functional microbial products in green ecological planting is very necessary,and it is worth further speeding up the demonstration and promotion.展开更多
The study aims to identify the potential acute effects of suspended aluminum nitride（Al N）nanoparticles（NPs） on soluble microbial products（SMP） of activated sludge.Cultured activated sludge loaded with 1,10,50,1...The study aims to identify the potential acute effects of suspended aluminum nitride（Al N）nanoparticles（NPs） on soluble microbial products（SMP） of activated sludge.Cultured activated sludge loaded with 1,10,50,100,150 and 200 mg/L of Al N NPs were carried out in this study.As results showed,Al N NPs had a highly inverse proportionality to bacterial dehydrogenase and OUR,indicating its direct toxicity to the activated sludge viability.The toxicity of Al N NPs was mainly due to the nano-scale of Al N NPs.In SMP,Al N NPs led to the decrease of polysaccharide and humic compounds,but had slight effects on protein.The decrease of tryptophan-like substances in SMP indicated the inhibition of Al N NPs on the bacterial metabolism.Additionally,Al N NPs reduced obviously the molecular weight of SMP,which might be due to the nano-scale of Al N.展开更多
GABA(Gamma-aminobutyric acid),a crucial neurotransmitter in the central nervous system,has gained significant attention in recent years due to its extensive benefits for human health.The review focused on recent advan...GABA(Gamma-aminobutyric acid),a crucial neurotransmitter in the central nervous system,has gained significant attention in recent years due to its extensive benefits for human health.The review focused on recent advances in the biosynthesis and production of GABA.To begin with,the investigation evaluates GABA-producing strains and metabolic pathways,focusing on microbial sources such as Lactic Acid Bacteria,Escherichia coli,and Corynebac-terium glutamicum.The metabolic pathways of GABA are elaborated upon,including the GABA shunt and critical enzymes involved in its synthesis.Next,strategies to enhance microbial GABA production are discussed,including optimization of fermentation factors,different fermentation methods such as co-culture strategy and two-step fermentation,and modification of the GABA metabolic pathway.The review also explores methods for determining glutamate(Glu)and GABA levels,emphasizing the importance of accurate quantification.Furthermore,a comprehensive market analysis and prospects are provided,highlighting current trends,potential applications,and challenges in the GABA industry.Overall,this review serves as a valuable resource for researchers and industrialists working on GABA advancements,focusing on its efficient synthesis processes and various applications,and providing novel ideas and approaches to improve GABA yield and quality.展开更多
<div style="text-align:justify;"> <span style="line-height:1.5;font-family:Verdana;"> <span style="font-family:"">C<span>arotenoids are isoprenoid pigments us...<div style="text-align:justify;"> <span style="line-height:1.5;font-family:Verdana;"> <span style="font-family:"">C<span>arotenoids are isoprenoid pigments used in food, chemical, text</span>ile, pharma<span>ceutical, and cosmetic industries. They act not only as </span>dyes and provitamins A but<span> also have antioxidants, photoprotective, anti</span>microbial properties, among others. This class of pigment can be obtained traditionally by plants or chemical synthesis, but they have some disadvantages. In recent years, search for alternative sources has been an important strategy for the carotenoid industries. Microbial synthesis is an alternative that has shown good yields, speed, <span>and reduced production costs. Hostile environments, such as the Caating</span>a dom<span>ain, represent an interesting source of microorganisms tha</span>t produce biomolecules, especially carotenoids, because of oxidative stress caused by sunlight. T<span>hus, this region has been attracting the attentio</span>n of the scientific community and industry for the use of these organisms in the production of carotenoids and applications in cosmetic products;since these compounds have interesti<span>ng antioxidant and photoprotective properties. In</span> this review, general characteristics of carotenoids, sources of production, industrial applicability, and commercialization will be discussed, as well as perspectives on the production of carotenoids from microorganisms isolated from the Caatinga and their application in anti-UV products.</span><span style="font-family:""></span> <p> <br /> </p> </span><span style="line-height:1.5;font-family:Verdana;"></span> </div> <span style="font-family:;" "=""></span>展开更多
It is very important to identify the dominant precursors for N-nitrosamine formation from bulk organic matter, to enhance the understanding of N-nitrosamine formation pathways in water treatment plants and allow the d...It is very important to identify the dominant precursors for N-nitrosamine formation from bulk organic matter, to enhance the understanding of N-nitrosamine formation pathways in water treatment plants and allow the development of practical treatment technologies. In this study, dissolved organic matter （DOM） from two source waters was fractionated with XAD resins and ultra- filtration membranes. The N-nitrosamine formation potential （FP） （ng of N-nitrosamines formed per mg of dissolved organic carbon （DOC）） from raw water and each fraction were measured and correlated with the fluorescence excitation-emission matrix （EEM）, molecular weight （MW） and other assays. The results showed that the hydrophilic fraction had N-nitrosamine FP 1.3 to 3.5 times higher than the hydrophobic fraction from both source waters. The DOM fraction with low MW was the dominant fraction in these two source waters and contributed more precursors for N-nitrosamine formation than the larger MW fraction. The EEM spectra indicated there were notable amounts of soluble microbial products （SMPs） and aromatic proteins in the two studied rivers, which probably originated from wastewater discharge. The SMPs tended to be more closely correlated with N-nitrosodimethylamine formation potential than the other DOM components. Higher N-nitrosamine FP were also related to fractions with lower DOC/DON ratios and lower SUVA254 values.展开更多
Dissolved organic nitrogen(DON) has attracted much attention in drinking water treatment due to its potential to produce nitrogenous disinfection by-products(N-DBPs). This work was designed to explore the transformati...Dissolved organic nitrogen(DON) has attracted much attention in drinking water treatment due to its potential to produce nitrogenous disinfection by-products(N-DBPs). This work was designed to explore the transformation and fate of DON and dissolved inorganic nitrogen(DIN) in drinking water treatment. The changes of DON and formation of N-DBPs were evaluated along the water treatment route(i.e., pre-ozonation and biologicalcontact oxidation, delivery pipes’ transportation, coagulation-sedimentation, sand filtration, post-ozonation, biological activated carbon, ultrafiltration and disinfection) of drinking water treatment plant(DWTP). The transformation mechanism of DON was comprehensively investigated by molecular weight fractionation, three-dimensional fluorescence, LCOCD(Liquid Chromatography-Organic Carbon Detection), total free amino acids. A detailed comparison was made between concentrations and variations of DON and DIN affected by seasons in the drinking water treatment. Regardless of seasonal variation in raw water concentration, the DON removal trends between different treatment processes remain constant in the present study. Compared to other treatment processes, pre-ozonation and coagulation-sedimentation exhibited the dominant DON removal in different seasons, i.e.,11.13%-14.45% and 14.98%-22.49%, respectively. Contrary, biological-contact oxidation and biological activated carbon negatively impacted the DON removal, in which DON increased by 1.76%-6.49% in biological activated carbon. This may be due to the release of soluble microbial products(SMPs) from bacterial metabolism, which was further validated by the rise of biopolymers in LC-OCD.展开更多
It is the key to control bio-derived dissolved organic matters (DOM) in order to reduce the effluent concentration of wastewater treatment, especially for waste leachate with high organic contaminants. In the present ...It is the key to control bio-derived dissolved organic matters (DOM) in order to reduce the effluent concentration of wastewater treatment, especially for waste leachate with high organic contaminants. In the present study, the anaerobic degradation of aerobically stabilized DOM was investigated with DOM substrate isolated through electrodialysis. The degradation of bio-derived DOM was confirmed by reduction of 15%of total organic carbon in 100 days.We characterized the molecular behavior of bio-derived DOM by coupling molecular and biological information analysis. Venn based Sankey diagram of mass features showed the transformation of bio-derived DOM mass features. Occurrence frequency analysis divided mass features into six categories so as to distinguish the fates of intermediate metabolites and persistent compounds. Reactivity continuum model and machine learning technologies realized the semi-quantitative determination on the kinetics of DOM mass features in the form of pseudo-first order, and confirmed the reduction of inert mass features. Furthermore, network analysis statistically establish relationship between DOM mass features and microbes to identify the active microbes that are able to utilize bio-derived DOM. This work confirmed the biological technology is still effective in controlling recalcitrant bio-derived DOM during wastewater treatment.展开更多
By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products （SMPs） and metal ions in activated sludge liquor on membrane fouling wer...By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products （SMPs） and metal ions in activated sludge liquor on membrane fouling were investigated. The results showed that foulants absorbed each other and formed a fouling layer as a ＂second membrane＂ influencing the permeability of the membrane. The ＂gel layer＂ caused by SMPs and ＂cake layer＂ by floes showed great differences in morphology by analysis of scanning electron microscope and atomic force microscope. The ＂gel layer＂ was more compact and of poor permeability. When the membrane flux was 40 L/（m^2·h）, the rate of membrane fouling caused by supernatant （0.011 MPa/h） was greater than that by sludgc liquor （0.0063 MPa/h）. SMPs played very important roles on membrane fouling. In the bulking sludge, with SMPs increasing, the rate of membrane fouling （0.0132 MPa/h） was faster. While after flocculation of the SMPs, the rate of fouling decreased to 0.0034 M Pa/h. Floes could keep holes in their overlaps. They could alleviate membrane fouling by preventing the SMPs directly attaching on membrane surface.展开更多
Highly hydrophobic Di 2-ethyl hexyl phthalate（DEHP） is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator ...Highly hydrophobic Di 2-ethyl hexyl phthalate（DEHP） is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand（COD）and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time（HRT） = 4 and 6 hr, sludge retention time（SRT） = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid（VS）/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor,which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.展开更多
Extracellular polymeric substances（EPS） are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions.Extracellular polysaccharides（EP） in EPS are res...Extracellular polymeric substances（EPS） are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions.Extracellular polysaccharides（EP） in EPS are responsible for the formation of microbial aggregates. In this work, we successfully separated and characterized EP from EPS of the bacterium Bacillus megaterium TF10. Extraction of EP from EPS was optimized using Sevag＇s reagent. Chemical characteristics, functional groups, and molecular weight（MW） distribution of EP were compared with the harvested EPS and soluble microbial products（SMP）. We found that the polymers of lower MW and free proteins were successfully removed by Sevag＇s reagent. The higher MW components of EPS were predominantly polysaccharides,while the polymers of lower MW tended to secrete to the supernatant and were described as SMP. A part of the proteins in the EP was polysaccharide-bonded. Our results can be further used in elucidating the complex flocculation mechanisms in which EP play a major role.展开更多
The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils w...The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils with pH above 6.5.Here,a substantial part of microbial CO_2 production is retained in soil solution(CO_2,aq)due to shifts in the carbonate equilibrium.This may lead to substantial errors in gas balance calculation.Yet,utilization of the BaPS technique is only reliable if the critical term is adequately quantified.We present an easy,inexpensive,and direct method,the sterilization-CO_2-injection(SCI)method,to measure CO_2 retention during soil incubation.Sterilized soil was incubated in the BaPS system,and defined volumes of CO_2 were injected to stepwise increase CO_2partial pressure(p CO_2)inside the chamber and to analyse the physicochemical equilibration process.Five exemplary agricultural soils from Northeast China and Southwest Germany were used for method establishment,presenting pH values between 4.4 and 7.6 and carbonate contents between 0% and 3.9%.We observed that in soils with pH>6.5,70%–90% of the injected CO_2 was taken up by the soil until the equilibrium inside the chamber was re-established.As expected,in soils with low pH(<6.5),measured CO_2 retention was low.CO_2 retention patterns were sensitive to incubation temperature with tri-fold dissolution capacity at 5~?C compared to 25?C,but insensitive to variations in soil water content.The resulting soil-specific relationship between p CO_2 and CO_2,aq concentration allowed the quantification of CO_2,aq concentration as a function of headspace p CO_2.展开更多
Starch containing wastewaters from the food and feed industry have been identified as potential cheap carbon sources for the production of microbial lipids. Due to its high potential lipid content the oleaginous yeast...Starch containing wastewaters from the food and feed industry have been identified as potential cheap carbon sources for the production of microbial lipids. Due to its high potential lipid content the oleaginous yeast Rhodotorula glutinis is often used for fermentations in this field. Moreover it is investigated in the context of microbial carotenoid production, which also requires a cheap source of carbon. Thus, the ability of R. glutinis (ATCC 15125TM) to degrade and utilize soluble starch for the production of lipids has been assessed in this study. While glucose and fructose were readily consumed from the medium, starch was only slightly reduced in one treatment. The yield of fatty acid methyl esters (FAME) was graduated corresponding to the initial sugar contents, with the highest FAME yield (1.5 g·L-1) at the highest initial sugar content. In the treatment that contained starch as single carbon source, no FAME production was realized. Accordingly, if starchy wastewaters should be used for microbial cultivation with R. glutinis, an enzymatic or chemical pretreatment for starch hydrolysis should be applied, to increase the availability of this carbon source.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(31871784,31870069,21676119 and 31671845)the National Key Research and Development Program of China(2018YFA0900300).
文摘Human milk oligosaccharides(HMOs)are one of the major differences between livestock milk and human milk,and the prebiotic functions of HMOs have been verified through in vitro and clinical trials.The most abundant HMOs include 2′-fucysollactose(2′-FL),3-fucosyllactose(3-FL),lacto-N-neotetraose(LNnT)and lacto-N-tetraose(LNT);their application and synthesis have attracted wide attentions.In recent years,the biotechnological production of 2′-FL,3-FL,LNnT and LNT have emerged based on techniques such as whole-cell catalysis and fermentation.In particular,the development of metabolic engineering and synthetic biology methods and strategies have facilitated efficient biosynthesis of these HMOs.However,these advantages have not been systematically reviewed yet.In this review,we first discuss the structures and applications of HMOs;secondly,strategies of microbial synthesis of the most abundant 2′-FL,3-FL,LNnT and LNT are summarized and compared.Finally,challenges and perspectives of efficient microbial production of HMOs as well as strategies for overcoming the challenges are discussed.This review reveals the whole picture of recent development in HMOs microbial synthesis and can further facilitate the understanding of limiting factors,and further propose a few directions to promote the development of efficient production hosts.
基金funded by an ARC Australian Laureate Fellowship(grant number FL210100071)to JE.FAS is supported by DOST-SEI Foreign Graduate Scholarship Program.
文摘Plants and microbes are closely associated with each other in their ecological niches.Much has been studied about plant-microbe interactions,but little is known about the effect of phytochemicals on microbes at the molecular level.To access the products of cryptic biosynthetic gene clusters in bacteria,we incorporated an organic extract of hibiscus flowers into the culture media of different Actinobacteria isolated from plant rhizospheres.This approach led to the production of broad-spectrum dithiolopyrrolone(DTP)antibiotics,thiolutin(1)and aureothricin(2),by Streptomyces sp.MBN2-2.The compounds from the hibiscus extract responsible for triggering the production of these two DTPs were found to be hibiscus acid dimethyl ester(3)and hydroxycitric acid 1,3-dimethyl ester(4).It was subsequently found that the addition of either Fe2+or Fe3+to culture media induced the production of 1 and 2.The Chrome Azurol S(CAS)assay revealed that 3 and 4 can chelate iron,and therefore,the mechanism leading to the production of thiolutin and aureothricin appears to be related to changes in iron concentration levels.This work supports the idea that phytochemicals can be used to activate the production of cryptic microbial biosynthetic gene clusters and further understand plant-microbe interactions.
文摘The effects of feed strength, hydraulic residence time （HRT）, and operational temperatures on soluble microbial product （SMP） production were investigated, to gain insights into the production mechanism. A carrier anaerobic baffled reactor （CABR） treating dilute wastewater was operated under a wide range of operational conditions, namely, feed strengths of 300-600 mg/L, HRTs of 9- 18 h, and temperatures of 10-28℃. Generally, SMP production increased with increasing feed strength and decreasing temperature. At high temperature （28℃）, SMP production increased with decreasing HRT. As the temperature was decreased to 18 and 10℃, the SMP production was at its peak for 12 h HRT. Therefore, temperature could be an important determinant of SMP production along with HRT. A higher SMP to soluble chemical oxygen demand （SCOD） ratio was found at high temperature and long HRT because of complete volatile fatty acid degradation. SMP accounted for 50%-75% of the SCOD in the last chamber of the CABR. As a secondary metabolite, some SMP could be consumed at lower feed strength.
基金supported by the National Natural Science Foundation of China (No. 50808121)the Program for New Century Excellent Talents in University (No. NCET-11-0320)
文摘The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon （BAC） was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket （UASB） reactors. The high strength organics were degraded in the first UASB reactor （UASB1） and the second UASB （UASB2, i.e., BAC） functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand （COD） was 10,000 mg/L and the organic loading rate achieved 10 kg COD/（m 3 ·day）, the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.
基金supported by the National Natural Science Foundation of China (Grant No. 50408026)
文摘Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products （SMP） during drinking water biofiltration. Four pilot-scale biofilters with ceramsite as the medium were fed with different acetate loadings for the determination of SMP formation. Using numerically simulated and measured parameters, the theoretical model was developed according to the substrate and biomass balance. The results of this model matched the measured data better for higher SMP formation but did not fit well when SMP formation was lower. In order to better simulate the reality and overcome the difficulties of measuring the kinetic parameters, a simpler empirical model was also developed. In this model, SMP formation was expressed as a function of fed organic loadings and the depth of the medium, and a much better fit was obtained.
基金supported by the National Natural Science Foundation of China (Nos. 51178215 and 51378251)the Jiangsu Nature Science Fund (No. BK2011032)+2 种基金Open Science Foundation of Jiangsu (No. 50808121)the National Science and Technology Major Project for Water Pollution Control and Treatment (No. 2012ZX07301-005)the 2012 Scientific Research Open Found of Jiangsu Key Laboratory of Environmental Engineering
文摘A two-phase anaerobic reactor fed with glucose substrate（3 g chemical oxygen demand（COD）/L） was used to investigate the effects of toxic metals on the degradation of organics and the soluble microbial product（SMP） formation. Low concentrations of Ni（II）（5 and10 mg/L） promoted the acid phase, whereas high concentrations（15, 20, and 25 mg/L）exhibited an inhibitory effect on, but did not alter the fermentative method, which mainly involved the fermentation of propionic acid. The methanogenic microorganism exhibited a strong capability adapting constantly increased Ni（II） levels. The acid phase was an accumulation stage of SMP. In the absence of Ni（II）, the high-molecular-weight material in the effluent SMP mainly contained polysaccharide, tryptophan, and casein. Methanogens metabolized most of the polysaccharide, the whole tryptophan content, and part of the casein, leading to the presence of humic acid and protein in effluent. After Ni（II） dosage, the protein and polysaccharide of the acid phase increased, and tryptophan changed, while casein remained stable. More protein than polysaccharide was produced, suggesting the prominent function of protein when addressing the negative effect of toxic metals. The analysis of DNA confirmed the change of bacterial activity.
基金Science and Technology Project of China Tobacco Guizhou Provincial Corporation(201918)Science and Technology Foundation of General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China(2017IK257,2017IK261,2016IK075,2014IK022)+3 种基金Science and Technology Foundation of Guizhou Province(J[2013]2149)Humanities and Social Science Research Project of Guizhou Education Department(2022ZC016)Theoretical Innovation Project of Guizhou Province(Joint Project)(GZLCLH-2021-169)Construction of Guizhou Academic Pioneer.
文摘[Objectives]The paper was to study the toxicity of 9 biocontrol microbial products to adult population of Lasioderrma serricorne.[Methods]Nine biocontrol microbes were used as test materials to study their toxicity to the experimental population of L.serricorne adults.[Results]The toxicities of these biocontrol microbes from low to high at 5 d post spraying were:Luhai Beauveria bassiana powder(LC_(50)=462.752×10^(8) spores/L),Meichongzhi B.bassiana powder(LC_(50)=9713.157×10^(8) spores/L),Yiqiang Bio B.bassiana powder(LC_(50)=11203.321×10^(8)spores/L),Nongbao Bio B.bassiana powder(LC_(50)=12188.866×10^(8) spores/L),Yeshengwang B.bassiana powder(LC_(50)=21685.532×10^(8) spores/L);Fatu Bacillus thuringiensis suspension(LC_(50)=1.0844×10^(8) IU/L),Laojite B.thuringiensis suspension(LC_(50)=2.056×10^(8) IU/L),Lujinwa B.thuringiensis powder(LC_(50)=2.273×10^(8) IU/L),Nongbao Bio B.thuringiensis powder(LC_(50)=18.399×10^(8) spores/L).The toxicities of these biocontrol microbes from low to high at 10 d post spraying were:Nongbao Bio B.bassiana powder(LC_(50)=0.072×10^(8) spores/L),Yiqiang Bio B.bassiana powder(LC_(50)=2.484×10^(8) spores/L),Luhai B.bassiana powder(LC_(50)=44.551×10^(8) spores/L),Meichongzhi B.bassiana powder(LC_(50)=96.447×10^(8) spores/L),Yeshengwang B.bassiana powder(LC_(50)=723.347×10^(8) spores/L);Lujinwa B.thuringiensis powder(LC_(50)=0.0001×10^(8) IU/L),Fatu B.thuringiensis suspension(LC_(50)=0.045×10^(8) IU/L),Laojite B.thuringiensis suspension(LC_(50)=0.0644×10^(8) IU/L),Nongbao Bio B.thuringiensis powder(LC_(50)=1.899×10^(8) spores/L).The toxicities of these biocontrol microbes from low to high at 15 d post spraying were:Meichongzhi B.bassiana powder(LC_(50)=0.001×10^(8) spores/L),Nongbao Bio B.bassiana powder(LC_(50)=0.01×10^(8) spores/L),Yiqiang Bio B.bassiana powder(LC_(50)=0.084×10^(8) spores/L),Luhai B.bassiana powder(LC_(50)=2.370×10^(8) spores/L),Yeshengwang B.bassiana powder(LC_(50)=8.915×10^(8)spores/L);Lujinwa B.thuringiensis powder(LC_(50)=0.16×10^(4) IU/L),Laojite B.thuringiensis suspension(LC_(50)=0.185×10^(4) IU/L),Fatu B.thuringiensis suspension(LC_(50)=32.211×10^(4) IU/L),Nongbao Bio B.thuringiensis powder(LC_(50)=1590×10^(4) spores/L).[Conclusions]According to the three stages of tube rubbing,it is found that the control effects of Lujinwa B.thuringiensis powder and Meichongzhi B.bassiana powder are the best,and the results will provide technical support for the biological control of L.serricorne adults.
基金supported by the National Natural Science Foundation of China (Nos. 51878244 and 52170032)the the Fundamental Research Funds for the Central Universities (No. B200202101)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), China
文摘Soluble microbial products(SMPs),dissolved organic matter excreted by activated sludge,can interact with antibiotics in wastewater and natural water bodies.Interactions between SMPs and antibiotics can influence antibiotic migration,transformation,and toxicity but the mechanisms involved in such interactions are not fully understood.In this study,integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic,trimethoprim(TMP),which has a low biodegradation rate and has been detected in wastewater.The results of liquid chromatography-organic carbon detection-organic nitrogen detection indicated that the SMPs used in the study contained 15% biopolymers and 28% humic-like substances(based on the total dissolved organic carbon concentration)so would have contained sites that could interact with TMP.A linear relationship of fluorescent intensities of tryptophan protein-like substances in SMP was observed(R^(2)>0.99),indicating that the fluorescence enhancement between SMP and TMP occurred.Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that carboxyl,carbonyl,and hydroxyl groups were the main functional groups involved in the interactions.The electrostatic andπ-πinteractions were discovered by the UV-vis spectra and 1H nuclear magnetic resonance spectra.Structural representations of the interactions between representative SMP subcomponents and TMP were calculated using density functional theory,and the results confirmed the conclusions drawn from the 1H nuclear magnetic resonance spectra.The results help characterize SMP–TMP complexes and will help understand antibiotic transformations in wastewater treatment plants and aquatic environments.
基金Supported by Zhenjiang Key R&D Program(NY2020017).
文摘In order to promote the transformation and high-quality development of strawberry industry and speed up the application of functional microbial products in strawberry,the application technology of functional microbial products in strawberry planting is studied and summarized.It mainly includes:the periods and methods of continuous cropping strawberry soil reduction and disinfection at high temperature,before and after strawberry planting,before plastic film mulching and whole process of plant spraying.Through multi-point test and demonstration,the purpose of advancing the season of strawberries,improving the quality,increasing production and increasing efficiency is achieved,and there is no risk of agricultural residue pollution,which meets the needs of people's consumption upgrading.Therefore,the application of functional microbial products in green ecological planting is very necessary,and it is worth further speeding up the demonstration and promotion.
基金supported by the National Natural Science Foundation of China(No.51378368)the Foundation of State Key Laboratory of Pollution Control and Resource Reuse(Tongji University),China(No.PCRRT16003)Shenzhen Science and Technology Research Fund(No.CXZZ20150330151321966)
文摘The study aims to identify the potential acute effects of suspended aluminum nitride（Al N）nanoparticles（NPs） on soluble microbial products（SMP） of activated sludge.Cultured activated sludge loaded with 1,10,50,100,150 and 200 mg/L of Al N NPs were carried out in this study.As results showed,Al N NPs had a highly inverse proportionality to bacterial dehydrogenase and OUR,indicating its direct toxicity to the activated sludge viability.The toxicity of Al N NPs was mainly due to the nano-scale of Al N NPs.In SMP,Al N NPs led to the decrease of polysaccharide and humic compounds,but had slight effects on protein.The decrease of tryptophan-like substances in SMP indicated the inhibition of Al N NPs on the bacterial metabolism.Additionally,Al N NPs reduced obviously the molecular weight of SMP,which might be due to the nano-scale of Al N.
基金financially supported by the National Key Research and Development Program of China(No.2019YFA0905700)the Natural Science Foundation of Jiangsu Province(BK20211535)+2 种基金Jiangsu agricultral science and technology innovation fund(CX233055)the Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture(XTD2213)Jiangsu Province“333”project(2022).
文摘GABA(Gamma-aminobutyric acid),a crucial neurotransmitter in the central nervous system,has gained significant attention in recent years due to its extensive benefits for human health.The review focused on recent advances in the biosynthesis and production of GABA.To begin with,the investigation evaluates GABA-producing strains and metabolic pathways,focusing on microbial sources such as Lactic Acid Bacteria,Escherichia coli,and Corynebac-terium glutamicum.The metabolic pathways of GABA are elaborated upon,including the GABA shunt and critical enzymes involved in its synthesis.Next,strategies to enhance microbial GABA production are discussed,including optimization of fermentation factors,different fermentation methods such as co-culture strategy and two-step fermentation,and modification of the GABA metabolic pathway.The review also explores methods for determining glutamate(Glu)and GABA levels,emphasizing the importance of accurate quantification.Furthermore,a comprehensive market analysis and prospects are provided,highlighting current trends,potential applications,and challenges in the GABA industry.Overall,this review serves as a valuable resource for researchers and industrialists working on GABA advancements,focusing on its efficient synthesis processes and various applications,and providing novel ideas and approaches to improve GABA yield and quality.
文摘<div style="text-align:justify;"> <span style="line-height:1.5;font-family:Verdana;"> <span style="font-family:"">C<span>arotenoids are isoprenoid pigments used in food, chemical, text</span>ile, pharma<span>ceutical, and cosmetic industries. They act not only as </span>dyes and provitamins A but<span> also have antioxidants, photoprotective, anti</span>microbial properties, among others. This class of pigment can be obtained traditionally by plants or chemical synthesis, but they have some disadvantages. In recent years, search for alternative sources has been an important strategy for the carotenoid industries. Microbial synthesis is an alternative that has shown good yields, speed, <span>and reduced production costs. Hostile environments, such as the Caating</span>a dom<span>ain, represent an interesting source of microorganisms tha</span>t produce biomolecules, especially carotenoids, because of oxidative stress caused by sunlight. T<span>hus, this region has been attracting the attentio</span>n of the scientific community and industry for the use of these organisms in the production of carotenoids and applications in cosmetic products;since these compounds have interesti<span>ng antioxidant and photoprotective properties. In</span> this review, general characteristics of carotenoids, sources of production, industrial applicability, and commercialization will be discussed, as well as perspectives on the production of carotenoids from microorganisms isolated from the Caatinga and their application in anti-UV products.</span><span style="font-family:""></span> <p> <br /> </p> </span><span style="line-height:1.5;font-family:Verdana;"></span> </div> <span style="font-family:;" "=""></span>
基金supported by the National Natural Science Foundation of China (No.51078208)the Major Science and Technology Program for Water Pollution Control and Treatment(No.2008ZX07420-005,2008X07423-002)
文摘It is very important to identify the dominant precursors for N-nitrosamine formation from bulk organic matter, to enhance the understanding of N-nitrosamine formation pathways in water treatment plants and allow the development of practical treatment technologies. In this study, dissolved organic matter （DOM） from two source waters was fractionated with XAD resins and ultra- filtration membranes. The N-nitrosamine formation potential （FP） （ng of N-nitrosamines formed per mg of dissolved organic carbon （DOC）） from raw water and each fraction were measured and correlated with the fluorescence excitation-emission matrix （EEM）, molecular weight （MW） and other assays. The results showed that the hydrophilic fraction had N-nitrosamine FP 1.3 to 3.5 times higher than the hydrophobic fraction from both source waters. The DOM fraction with low MW was the dominant fraction in these two source waters and contributed more precursors for N-nitrosamine formation than the larger MW fraction. The EEM spectra indicated there were notable amounts of soluble microbial products （SMPs） and aromatic proteins in the two studied rivers, which probably originated from wastewater discharge. The SMPs tended to be more closely correlated with N-nitrosodimethylamine formation potential than the other DOM components. Higher N-nitrosamine FP were also related to fractions with lower DOC/DON ratios and lower SUVA254 values.
文摘Dissolved organic nitrogen(DON) has attracted much attention in drinking water treatment due to its potential to produce nitrogenous disinfection by-products(N-DBPs). This work was designed to explore the transformation and fate of DON and dissolved inorganic nitrogen(DIN) in drinking water treatment. The changes of DON and formation of N-DBPs were evaluated along the water treatment route(i.e., pre-ozonation and biologicalcontact oxidation, delivery pipes’ transportation, coagulation-sedimentation, sand filtration, post-ozonation, biological activated carbon, ultrafiltration and disinfection) of drinking water treatment plant(DWTP). The transformation mechanism of DON was comprehensively investigated by molecular weight fractionation, three-dimensional fluorescence, LCOCD(Liquid Chromatography-Organic Carbon Detection), total free amino acids. A detailed comparison was made between concentrations and variations of DON and DIN affected by seasons in the drinking water treatment. Regardless of seasonal variation in raw water concentration, the DON removal trends between different treatment processes remain constant in the present study. Compared to other treatment processes, pre-ozonation and coagulation-sedimentation exhibited the dominant DON removal in different seasons, i.e.,11.13%-14.45% and 14.98%-22.49%, respectively. Contrary, biological-contact oxidation and biological activated carbon negatively impacted the DON removal, in which DON increased by 1.76%-6.49% in biological activated carbon. This may be due to the release of soluble microbial products(SMPs) from bacterial metabolism, which was further validated by the rise of biopolymers in LC-OCD.
基金supported by the National Key R&D Program of China (No. 2018YFC1903700)National Natural Science Foundation of China (No. 22076145)。
文摘It is the key to control bio-derived dissolved organic matters (DOM) in order to reduce the effluent concentration of wastewater treatment, especially for waste leachate with high organic contaminants. In the present study, the anaerobic degradation of aerobically stabilized DOM was investigated with DOM substrate isolated through electrodialysis. The degradation of bio-derived DOM was confirmed by reduction of 15%of total organic carbon in 100 days.We characterized the molecular behavior of bio-derived DOM by coupling molecular and biological information analysis. Venn based Sankey diagram of mass features showed the transformation of bio-derived DOM mass features. Occurrence frequency analysis divided mass features into six categories so as to distinguish the fates of intermediate metabolites and persistent compounds. Reactivity continuum model and machine learning technologies realized the semi-quantitative determination on the kinetics of DOM mass features in the form of pseudo-first order, and confirmed the reduction of inert mass features. Furthermore, network analysis statistically establish relationship between DOM mass features and microbes to identify the active microbes that are able to utilize bio-derived DOM. This work confirmed the biological technology is still effective in controlling recalcitrant bio-derived DOM during wastewater treatment.
基金The National Basic Research Program (973) of China (No. 2004CB418505) and the Teaching and Research Award Program forOutstanding Young Teachers in Higher Education Institutions of MOE, China
文摘By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products （SMPs） and metal ions in activated sludge liquor on membrane fouling were investigated. The results showed that foulants absorbed each other and formed a fouling layer as a ＂second membrane＂ influencing the permeability of the membrane. The ＂gel layer＂ caused by SMPs and ＂cake layer＂ by floes showed great differences in morphology by analysis of scanning electron microscope and atomic force microscope. The ＂gel layer＂ was more compact and of poor permeability. When the membrane flux was 40 L/（m^2·h）, the rate of membrane fouling caused by supernatant （0.011 MPa/h） was greater than that by sludgc liquor （0.0063 MPa/h）. SMPs played very important roles on membrane fouling. In the bulking sludge, with SMPs increasing, the rate of membrane fouling （0.0132 MPa/h） was faster. While after flocculation of the SMPs, the rate of fouling decreased to 0.0034 M Pa/h. Floes could keep holes in their overlaps. They could alleviate membrane fouling by preventing the SMPs directly attaching on membrane surface.
基金the National Sciences and Engineering Research Council of Canada (NSERC Grant Number: I2IPJ 461378)
文摘Highly hydrophobic Di 2-ethyl hexyl phthalate（DEHP） is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand（COD）and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time（HRT） = 4 and 6 hr, sludge retention time（SRT） = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid（VS）/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor,which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.
基金supported by the National Natural Science Foundation of China (No. 21607031)Science and Technology Planning Project of Guangdong Province, China (Nos. 2014A010107023, 2015B020230002, and 2016A010103020)
文摘Extracellular polymeric substances（EPS） are organic metabolic compounds excreted by microorganisms. They largely impact microbial aggregate structures and functions.Extracellular polysaccharides（EP） in EPS are responsible for the formation of microbial aggregates. In this work, we successfully separated and characterized EP from EPS of the bacterium Bacillus megaterium TF10. Extraction of EP from EPS was optimized using Sevag＇s reagent. Chemical characteristics, functional groups, and molecular weight（MW） distribution of EP were compared with the harvested EPS and soluble microbial products（SMP）. We found that the polymers of lower MW and free proteins were successfully removed by Sevag＇s reagent. The higher MW components of EPS were predominantly polysaccharides,while the polymers of lower MW tended to secrete to the supernatant and were described as SMP. A part of the proteins in the EP was polysaccharide-bonded. Our results can be further used in elucidating the complex flocculation mechanisms in which EP play a major role.
基金funded by the German Research Foundation (DFG) in the framework of the SinoGerman Research Training Group "Sustainable Resource Use in North China"
文摘The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils with pH above 6.5.Here,a substantial part of microbial CO_2 production is retained in soil solution(CO_2,aq)due to shifts in the carbonate equilibrium.This may lead to substantial errors in gas balance calculation.Yet,utilization of the BaPS technique is only reliable if the critical term is adequately quantified.We present an easy,inexpensive,and direct method,the sterilization-CO_2-injection(SCI)method,to measure CO_2 retention during soil incubation.Sterilized soil was incubated in the BaPS system,and defined volumes of CO_2 were injected to stepwise increase CO_2partial pressure(p CO_2)inside the chamber and to analyse the physicochemical equilibration process.Five exemplary agricultural soils from Northeast China and Southwest Germany were used for method establishment,presenting pH values between 4.4 and 7.6 and carbonate contents between 0% and 3.9%.We observed that in soils with pH>6.5,70%–90% of the injected CO_2 was taken up by the soil until the equilibrium inside the chamber was re-established.As expected,in soils with low pH(<6.5),measured CO_2 retention was low.CO_2 retention patterns were sensitive to incubation temperature with tri-fold dissolution capacity at 5~?C compared to 25?C,but insensitive to variations in soil water content.The resulting soil-specific relationship between p CO_2 and CO_2,aq concentration allowed the quantification of CO_2,aq concentration as a function of headspace p CO_2.
文摘Starch containing wastewaters from the food and feed industry have been identified as potential cheap carbon sources for the production of microbial lipids. Due to its high potential lipid content the oleaginous yeast Rhodotorula glutinis is often used for fermentations in this field. Moreover it is investigated in the context of microbial carotenoid production, which also requires a cheap source of carbon. Thus, the ability of R. glutinis (ATCC 15125TM) to degrade and utilize soluble starch for the production of lipids has been assessed in this study. While glucose and fructose were readily consumed from the medium, starch was only slightly reduced in one treatment. The yield of fatty acid methyl esters (FAME) was graduated corresponding to the initial sugar contents, with the highest FAME yield (1.5 g·L-1) at the highest initial sugar content. In the treatment that contained starch as single carbon source, no FAME production was realized. Accordingly, if starchy wastewaters should be used for microbial cultivation with R. glutinis, an enzymatic or chemical pretreatment for starch hydrolysis should be applied, to increase the availability of this carbon source.
