Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated ...Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.展开更多
The catalysis of four carbon materials including artificial graphite(AG), carbon black(CB), activated carbon(AC) and carbon nanotube(CN) on chalcopyrite bioleaching by mixed moderate thermophiles was comparatively inv...The catalysis of four carbon materials including artificial graphite(AG), carbon black(CB), activated carbon(AC) and carbon nanotube(CN) on chalcopyrite bioleaching by mixed moderate thermophiles was comparatively investigated. In AC and AG added bioleaching groups, low solution pH and suitable redox potential values, high total iron and ferric iron concentrations, and large number of adsorbed bacteria were obtained, resulting in high copper extractions. CB and CN inhibited the growth of bioleaching bacteria and led to the low bioleaching efficiency.X-ray diffraction analysis showed that jarosite and sulfur film were the main components of passivation layer with the addition of AG and AC,but did not hinder the dissolution of chalcopyrite. Microbial community structures of free and attached cells in AC and AG added groups changed dramatically compared with mixed moderate thermophiles. The sulfur-oxidizing bacteria of A. caldus S1 strain dominated the microbial community(93%-98%) at the end of bioleaching.The iron-oxidizing bacteria of L.ferriphilum YSK only accounted for low percentage(1%-2%).展开更多
Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophi...Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophilic conditions,hence we employed X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium,and explored the role of free and attached microorganisms in the formation of AMD.The consortium mainly comprised Acidithiobacillus caldus,Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day,and the copper dissolution rate of bornite dissolution reached 91.8%on the 24th day.SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms.XRD and XPS results showed that ore residues contained jarosite,and the dissolving residue of bornite contained elemental sulfur.The dominant bacterial genus in pyrite dissolution was A.caldus,and L.ferriphilum in bornite dissolution.To sum up,microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.展开更多
The enzyme β-galactosidase （lactase; EC 3.2.1.23） is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lac...The enzyme β-galactosidase （lactase; EC 3.2.1.23） is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lactose into glucose and galactose. The objectives of this work were to identify novel and attractive sources of this industrially relevant enzyme, and to study the effect of selected growth parameters （carbon source, lactose concentration, nitrogen source, peptone concentration, initial pH and temperature） on the formation of β-galactosidase. Based on a screening of isolates from Tha Pai hot spring, Mae Hong Son Province, Thailand, strain BI.1 was selected for further studies. Strain BI.1 is a Gram-positive, rod-shaped, catalase-positive bacterium that forms endospores. Based on the sequence of the 16S rDNA determined, this isolate is most closely related to Anoxybacillus sp. and Bacillus sp., and hence the strain is designated as Bacillus sp. B 1. I.β-Galactosidase was produced by this strain with lactose and peptone as carbon and nitrogen sources, respectively. Optimal enzyme production occurred at an initial culture pH of 8.5 and at 45 ℃. Under these optimum culture conditions, maximal volumetric and specific β-galactosidase activity of 0.478 U mL^-1 and 0.338 U mg^-1 protein, respectively, were obtained after 13 h of cultivation in a medium contain 2.5% lactose, 2.0% peptone, 0.3% K2HPO4, 0.1% KH2PO4 and 0.05% MgSOa·7H2O.展开更多
The depletion of fossil fuels and their impact on the environment have led to efforts to develop alternative sustainable fuels.While biofuel derived from lignocellulose is considered a sustainable,renewable,and green ...The depletion of fossil fuels and their impact on the environment have led to efforts to develop alternative sustainable fuels.While biofuel derived from lignocellulose is considered a sustainable,renewable,and green energy source,enhancing biofuel production and achieving a cost-effective bioconversion of lignocellulose at existing bio-refineries remains a challenge.Consolidated bioprocessing(CBP)using thermophiles can simplify this operation by integrating multiple processes,such as hydrolytic enzyme production,lignocellulose degrada-tion,biofuel fermentation,and product distillation.This paper reviews recent developments in the conversion of lignocellulose to biofuel using thermophile-based CBP.First,advances in thermostable enzyme and thermophilic lignocellulolytic microorganism discovery and development for lignocellulosic biorefinery use are outlined.Then,several thermophilic CBP candidates and thermophilic microbes engineered to drive CBP of lignocellulose are reviewed.CRISPR/Cas-based genome editing tools developed for thermophiles are also highlighted.The poten-tial applications of the Design-Build-Test-Learn(DBTL)synthetic biology strategy for designing and constructing thermophilic CBP hosts are also discussed in detail.Overall,this review illustrates how to develop highly sophis-ticated thermophilic CBP hosts for use in lignocellulosic biorefinery applications.展开更多
A microbial strain designated Bacillus licheniformis QX928 was screened from hot springs in Sichuan Province,China,and a compound generated in the culture of this strain clearly inhibited Pseudomonas aeruginosa ATCC27...A microbial strain designated Bacillus licheniformis QX928 was screened from hot springs in Sichuan Province,China,and a compound generated in the culture of this strain clearly inhibited Pseudomonas aeruginosa ATCC27853.The measured minimum inhibitory and lowest bactericidal concentrations were(13±0.17)and(22±0.72)mg L^(-1),respectively.The compound was identified as 3-isopropylhexahydro-4H-pyrido[1,2-α]pyrazine-1,4(6H)-dione(IPHPPD).A Sci Finder search revealed that IPHPPD could be the first compound synthesized by microorganisms that had both antibacterial and anti-quorum sensing properties.At low concentrations,IPHPPD interfered with the signaling factors and population effects of P.aeruginosa,thereby altering the biofilm morphology and structure.IPHPPD more strongly inhibited P.aeruginosa at high concentrations,primarily by reducing its virulence factors,cell membrane permeability and energy metabolism.A transcriptome analysis highlighted the role of IPHPPD in the transcriptional regulation of cellular metabolism and quorum sensing.Thus,the results of this study provide critical evidence that IPHPPD is a potential target for drug development to prevent and treat diseases in animals.展开更多
Thermophilic proteins maintain their structure and function at high temperatures,making them widely useful in industrial applications.Due to the complexity of experimental measurements,predicting the melting temperatu...Thermophilic proteins maintain their structure and function at high temperatures,making them widely useful in industrial applications.Due to the complexity of experimental measurements,predicting the melting temperature(T_(m))of proteins has become a research hotspot.Previous methods rely on amino acid composition,physicochemical properties of proteins,and the optimal growth temperature(OGT)of hosts for T_(m)prediction.However,their performance in predicting T_(m)values for thermophilic proteins(T_(m)>60℃)are generally unsatisfactory due to data scarcity.Herein,we introduce T_(m)Pred,a T_(m)prediction model for thermophilic proteins,that combines protein language model,graph convolutional network and Graphormer module.For performance evaluation,T_(m)Pred achieves a root mean square error(RMSE)of 5.48℃,a pearson correlation coefficient(P)of 0.784,and a coefficient of determination(R~2)of 0.613,representing improvements of 19%,15%,and 32%,respectively,compared to the state-of-the-art predictive models like DeepTM.Furthermore,T_(m)Pred demonstrated strong generalization capability on independent blind test datasets.Overall,T_(m)Pred provides an effective tool for the mining and modification of thermophilic proteins by leveraging deep learning.展开更多
The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and the...The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.展开更多
X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of ...X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.展开更多
The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied....The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.展开更多
Bioleaching of chalcopyrite often encountered the formation of passivation layer, which inhibited the leaching process and resulted in a low leaching rate. This inhibitory effect can be eliminated by thermophilic biol...Bioleaching of chalcopyrite often encountered the formation of passivation layer, which inhibited the leaching process and resulted in a low leaching rate. This inhibitory effect can be eliminated by thermophilic biole- aching. The industrial test of BioCOP technology based on thermophiles was successfully completed, which confirmed the feasibility of chalcopyrite bioleaching. However, industrial leaching rate of chalcopyrite heap bioleaching is lower. This paper described the development status and industrial test of chalcopyrite heap bioleaching technology. The reasons for the lower efficiency of chalcopyrite heap bioleaching were analyzed. The strategies for successful chalcopyrite heap bioleaching were proposed.展开更多
Viruses of thermophiles are of great interest due to their roles in gene transfer, global geochemical cycle and evolution of life on earth. However, the thermophilic bacteriophages have not been studied extensively. I...Viruses of thermophiles are of great interest due to their roles in gene transfer, global geochemical cycle and evolution of life on earth. However, the thermophilic bacteriophages have not been studied extensively. In this investigation, a typical bacteriophage BV1 was obtained from a thermophilic bacterium Geobacillus sp. 6k512, which was isolated from an inshore hot spring in Xiamen of China. The BV1 contained a double-stranded linear DNA of 35 055 bp, which encodes 54 open reading frames （ORFs）. Interestingly, eight of the 54 BV1 ORFs shared sequence similarities to genes from human disease-relevant bacteria. Seven proteins of the purified BV1 virions were identified by proteomic analysis. Determination of BV1 functional genomics would facilitate the better understanding of the mechanism for virus-thermophile interaction.展开更多
The attachment and bioleaching experiments were conducted to evaluate the zinc recovery from Hualilan ore by thethermoacidophilic archaeon Acidianus copahuensis. Cells of this species pregrown on tetrathionate showed ...The attachment and bioleaching experiments were conducted to evaluate the zinc recovery from Hualilan ore by thethermoacidophilic archaeon Acidianus copahuensis. Cells of this species pregrown on tetrathionate showed higher capability ofattachment to the ore than cells pregrown on other energy sources and such attachment seemed to be mediated by the product ofextracellular polymeric substances. A. copahuensis achieved a successful bioleaching of the ore reaching 100% of zinc recoverywhen tetrathionate was added. Simultaneous addition of yeast extract and tetrathionate maintained the zinc extraction at higher rate.Zinc dissolution kinetics was controlled by chemical reaction in cultures with the external addition of tetrathionate but by thediffusion through a product layer of jarosite in the other cultures.展开更多
Acidogenic dissimilation of synthetic starch wastewater (1 000～10 000 mg COD·L -1 ) was studied in a thermophilic (55 ℃) upflow anaerobic sludge blanket (UASB) reactor.The production of volatile fatty acids...Acidogenic dissimilation of synthetic starch wastewater (1 000～10 000 mg COD·L -1 ) was studied in a thermophilic (55 ℃) upflow anaerobic sludge blanket (UASB) reactor.The production of volatile fatty acids (VFA) was proportional to the chemical oxygen demand (COD) loading rate.The yield of VFA was around 0.28 g VFA/g COD over the COD loading rate from 1.25 to 30 g COD·L -1 ·d -1 and the hydraulic retention time from 8.8 h to 24 h.Distribution of organic acids,the contents of propionic and butyric acids in the effluent in particular were also dependent on the COD loading rate.The thermophilic UASB reactor showed a stable performance on hydrolysis and acidogenesis of starch as well as suspended solid removal at short hydraulic retention times and high influent pH(10～11),during the operation of 110 d.展开更多
[Objective] The aim was to study the physiological and biochemical char- acteristics of Thermoanaerobacter sp DF3 in petroleum reservoirs and optimize the culture plan of producing ethanol from xylose. [Method] DF3, a...[Objective] The aim was to study the physiological and biochemical char- acteristics of Thermoanaerobacter sp DF3 in petroleum reservoirs and optimize the culture plan of producing ethanol from xylose. [Method] DF3, an anaerobic bacillus producing ethanol, was isolated from produced liquid from oil layer of Dagang oil field with anaerobic isolation technique. The phylogenetic position was analyzed by physiological and biochemical identification and phylogeny of 16S rDNA sequence. The metabolites were analyzed by gas chromatograph. [Result] The strain DF3 was a strict anaerobic thermophilic bacterium, which was straight in rod shape,and gram negative. Besides, it was 0.42 μmx（1.60-5.20） iJm in length. The strains can be soli- tary,in pairs or string and apical spore usually produced. Its growth temperature was 45-78 and 65 ℃ was the optimum. Many substances could be used as carbon sources, including glucose, xylose, fructose, ribose, mannose, arabinose, sucrose, galactose, lactose, cellobiose, melizitose, raffinose-, and starch. The similarity between strain DF3 and T. pseudoethanolicus achieved 99.7%. The main product of glucose and xylose fermentation was ethanol. After the culture plan was optimized,the final concentration of ethanol was 2.0 g/L. [Conclusion] It was proved through experiments that the strain DF3 was one of the strains with higher activity to produce ethanol at present and it could produce 2.0 g/L ethanol from xylose metabolization at 65 ℃. It has been demonstrated that DF3 is one of the known strains with high-production to produce ethanol,for example, 2.0 g/L ethano at 65℃. Presently, all the high-yield ethanol can be produced from metabolic xylose strains of metabolic xylose were isolat- ed by foreign countries, therefore, isolation of strain DF3 has provided an excellent original strain for studying ethanol production from lignocellulose in China.展开更多
Live cell imaging methods provide important insights into the dynamics of cellular processes that cannot be derived easily from population-averaged datasets.In the bioenergy field,much research is focused on fermentat...Live cell imaging methods provide important insights into the dynamics of cellular processes that cannot be derived easily from population-averaged datasets.In the bioenergy field,much research is focused on fermentation of cellulosic biomass by thermophilic microbes to produce biofuels;however,little effort is dedicated to the development of imaging tools to monitor this dynamic biological process.This is,in part,due to the experimental challenges of imaging cells under both anaerobic and thermophilic conditions.Here an imaging system is described that integrates confocal microscopy,a flow cell device,and a lipophilic dye to visualize cells.Solutions to technical obstacles regarding suitable fluorescent markers,photodamage during imaging,and maintenance of environmental conditions during imaging are presented.This system was utilized to observe cellulose colonization by Clostridium thermocellum under anaerobic conditions at 60℃.This method enables live cell imaging of bacterial growth under anaerobic and thermophilic conditions and should be widely applicable to visualizing different cell types or processes in real time.展开更多
Glutamate dehydrogenase （GDH） catalyzes the oxidative deamination of glutamate to a-ketoglutarate and ammonium ions. Currently the determination of ammonium and glutamate is carried out using a bovine GDH enzyme, wh...Glutamate dehydrogenase （GDH） catalyzes the oxidative deamination of glutamate to a-ketoglutarate and ammonium ions. Currently the determination of ammonium and glutamate is carried out using a bovine GDH enzyme, which lacks optimal thermostability for long term storage at room temperature. From samples of Deception Island, Antarctica, we obtained the thermophilic bacteria PID 15 belonging to the Bacillus genera with high GDH specific activity. This new enzyme exhibited NAD＋ dependent activity and no activity was observed when NADP＋ was used. This enzyme shows a specific activity of 4.7 U.mg-1 for the oxidative deamination reaction and 15.4 U·mg-1 for the reduction of a-ketoglutarate. This enzyme has an optimum temperature of 65℃ and pH of 8.5 for the oxidative deamination. For the reduction of a-ketoglutarate, the optimum temperature is 60℃, with a pH of 8.0. One of the most important characteristics of this enzyme is its ability to retain more than 60% of its activity when it is incubated for 8 h at 65℃. The enzyme is also able to retain full activity when it is incubated for 48 d at 4℃ and over 80% of its activity when it is incubated at 25℃. Characterization of its kinetics suggests that it primarily catalyzes the formation of α-ketoglutarate. This enzyme has an important biological role in the catabolism of glutamate and may have some interesting biotechnological applications based on its thermostable properties.展开更多
Thermoanaerobacterium thermosaccharolyticum shows promise as a host for n-butanol production since it natively has the required genes involved in the n-butanol biosynthetic pathway. Overexpression of the natively occu...Thermoanaerobacterium thermosaccharolyticum shows promise as a host for n-butanol production since it natively has the required genes involved in the n-butanol biosynthetic pathway. Overexpression of the natively occurring bcs operon containing the genes thl, hbd, crt, bcd, etfA, and etfB responsible for the formation of butyryl CoA increased the n-butanol production by 180% compared to the wild type from a n-butanol titer of 1.8 mM to 5.1 mM. The deletion of one of the six alcohol dehydrogenase genes confirmed that it was the primary gene responsible for ethanol and n-butanol production from acetyl CoA and butyryl CoA respectively.展开更多
Abundant virus-like particles were concentrated from large-volume samples from two hot springs. Both addition of viral concentrates and addition of samples induced by addition of mitomycin-C changed patterns of carbon...Abundant virus-like particles were concentrated from large-volume samples from two hot springs. Both addition of viral concentrates and addition of samples induced by addition of mitomycin-C changed patterns of carbon source utilization by hot spring microbial communities. Specific effects of the two treatments depended upon both temperature and incubation period. Increased metabolic capability with greater exposure to free phages, consistent with the view that phages are major lateral transporters of metabolic genes, was observed most clearly in microbes incubated at a temperature lower than that encountered in situ. On the other hand, decreases in the diversity of utilizable C sources upon exposure to phages may have been due to lytic activity in which susceptible bacterial populations were differentially reduced by infective viruses, consistent with the “killing the winner” hypothesis. Treatment of cultures with MC-treated culture extracts, assumed to increase exposure to excised prophages, resulted in higher average metabolic rates after 18 h, but lower rates after 48 h of incubation. With incubation at in situ temperature, this same treatment led to an initial increase in the number of readily utilized C sources, followed by a decrease in community metabolic diversity relative to controls in samples from both hot springs. Thus, treatments designed to increase the interaction between hot spring microbes and either free or newly-excised phages had observable time- and temperature-dependent effects on community metabolism, demonstrating an important, yet complex, ecological role for phages in hot spring waters.展开更多
Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic a...Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e., β-glucosidase, N-α-benzoyl-Largininamide （BAA）-hydrolysing protease, urease and phosphatase activities were analysed. The BAA-hydrolysing protease activity during the first 2-3 weeks was low with low pH, but was enhanced later with the pH increase. β-Glucosidase activity showed the lowest values in weeks 1-2, and recovered with the increase of BAA-hydrolysing protease activity. Acetic acid dominated most of the total VFAs in thermophilic digestion, while propionate and butyrate dominated in mesophilic digestion. Thermophilic digestion was confirmed more feasible for achieving better performance against misbalance, especially during the start-up period in a dry anaerobic digestion process.展开更多
基金Project (2012zzts026) supported by the Fundamental Research Funds for the Central Universities,ChinaProject (201205020) supported by Scientific Research Program of Marine Public Welfare Industry of China+2 种基金Project (51074195) supported by the National Natural Science Foundation of ChinaProject (CX2012B123) supported by Research Innovation for Graduate Student of Hunan Province,ChinaProject (12C517) supported by Education Department of Hunan Province,China
文摘Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.
基金Project(31570113)supported by the National Natural Science Foundation of ChinaProject(2016YFB0101310)supported by the National Key Research and Development Program of China
文摘The catalysis of four carbon materials including artificial graphite(AG), carbon black(CB), activated carbon(AC) and carbon nanotube(CN) on chalcopyrite bioleaching by mixed moderate thermophiles was comparatively investigated. In AC and AG added bioleaching groups, low solution pH and suitable redox potential values, high total iron and ferric iron concentrations, and large number of adsorbed bacteria were obtained, resulting in high copper extractions. CB and CN inhibited the growth of bioleaching bacteria and led to the low bioleaching efficiency.X-ray diffraction analysis showed that jarosite and sulfur film were the main components of passivation layer with the addition of AG and AC,but did not hinder the dissolution of chalcopyrite. Microbial community structures of free and attached cells in AC and AG added groups changed dramatically compared with mixed moderate thermophiles. The sulfur-oxidizing bacteria of A. caldus S1 strain dominated the microbial community(93%-98%) at the end of bioleaching.The iron-oxidizing bacteria of L.ferriphilum YSK only accounted for low percentage(1%-2%).
基金Projects(51934009,52074353)supported by the National Natural Science Foundation of ChinaProject(2019YFC1803600)supported by the National Key Research and Development Program of ChinaProject(2021JJ30855)supported by the Natural Science Foundation of Hunan Province,China。
文摘Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophilic conditions,hence we employed X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium,and explored the role of free and attached microorganisms in the formation of AMD.The consortium mainly comprised Acidithiobacillus caldus,Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day,and the copper dissolution rate of bornite dissolution reached 91.8%on the 24th day.SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms.XRD and XPS results showed that ore residues contained jarosite,and the dissolving residue of bornite contained elemental sulfur.The dominant bacterial genus in pyrite dissolution was A.caldus,and L.ferriphilum in bornite dissolution.To sum up,microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.
文摘The enzyme β-galactosidase （lactase; EC 3.2.1.23） is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lactose into glucose and galactose. The objectives of this work were to identify novel and attractive sources of this industrially relevant enzyme, and to study the effect of selected growth parameters （carbon source, lactose concentration, nitrogen source, peptone concentration, initial pH and temperature） on the formation of β-galactosidase. Based on a screening of isolates from Tha Pai hot spring, Mae Hong Son Province, Thailand, strain BI.1 was selected for further studies. Strain BI.1 is a Gram-positive, rod-shaped, catalase-positive bacterium that forms endospores. Based on the sequence of the 16S rDNA determined, this isolate is most closely related to Anoxybacillus sp. and Bacillus sp., and hence the strain is designated as Bacillus sp. B 1. I.β-Galactosidase was produced by this strain with lactose and peptone as carbon and nitrogen sources, respectively. Optimal enzyme production occurred at an initial culture pH of 8.5 and at 45 ℃. Under these optimum culture conditions, maximal volumetric and specific β-galactosidase activity of 0.478 U mL^-1 and 0.338 U mg^-1 protein, respectively, were obtained after 13 h of cultivation in a medium contain 2.5% lactose, 2.0% peptone, 0.3% K2HPO4, 0.1% KH2PO4 and 0.05% MgSOa·7H2O.
基金This work was supported by the Natural Science Foundation of Jiangsu Province,China(Grant NO.BK20231326)National Key R&D Program of China(2020YFA0906800)State Key Laboratory of Micro-bial Technology Open Projects Fund(Project NO.M2022-10).
文摘The depletion of fossil fuels and their impact on the environment have led to efforts to develop alternative sustainable fuels.While biofuel derived from lignocellulose is considered a sustainable,renewable,and green energy source,enhancing biofuel production and achieving a cost-effective bioconversion of lignocellulose at existing bio-refineries remains a challenge.Consolidated bioprocessing(CBP)using thermophiles can simplify this operation by integrating multiple processes,such as hydrolytic enzyme production,lignocellulose degrada-tion,biofuel fermentation,and product distillation.This paper reviews recent developments in the conversion of lignocellulose to biofuel using thermophile-based CBP.First,advances in thermostable enzyme and thermophilic lignocellulolytic microorganism discovery and development for lignocellulosic biorefinery use are outlined.Then,several thermophilic CBP candidates and thermophilic microbes engineered to drive CBP of lignocellulose are reviewed.CRISPR/Cas-based genome editing tools developed for thermophiles are also highlighted.The poten-tial applications of the Design-Build-Test-Learn(DBTL)synthetic biology strategy for designing and constructing thermophilic CBP hosts are also discussed in detail.Overall,this review illustrates how to develop highly sophis-ticated thermophilic CBP hosts for use in lignocellulosic biorefinery applications.
基金supported by the Guangdong Basic and Applied Basic Research Foundation,China(2024A1515012511 and 2022A1515012380)the Guangdong Special Project on Key Fields of Colleges and Universities,China(Rural Revitalization,2020ZDZX1020)+1 种基金the Science and Technology Special Fund Project of Maoming Science and Technology Bureau,China(2021KJZXZJGSPDX003)the Projects of Talents Rec r uitment of G uangdong Univer sit y of Petrochemical Technology,China(519033)。
文摘A microbial strain designated Bacillus licheniformis QX928 was screened from hot springs in Sichuan Province,China,and a compound generated in the culture of this strain clearly inhibited Pseudomonas aeruginosa ATCC27853.The measured minimum inhibitory and lowest bactericidal concentrations were(13±0.17)and(22±0.72)mg L^(-1),respectively.The compound was identified as 3-isopropylhexahydro-4H-pyrido[1,2-α]pyrazine-1,4(6H)-dione(IPHPPD).A Sci Finder search revealed that IPHPPD could be the first compound synthesized by microorganisms that had both antibacterial and anti-quorum sensing properties.At low concentrations,IPHPPD interfered with the signaling factors and population effects of P.aeruginosa,thereby altering the biofilm morphology and structure.IPHPPD more strongly inhibited P.aeruginosa at high concentrations,primarily by reducing its virulence factors,cell membrane permeability and energy metabolism.A transcriptome analysis highlighted the role of IPHPPD in the transcriptional regulation of cellular metabolism and quorum sensing.Thus,the results of this study provide critical evidence that IPHPPD is a potential target for drug development to prevent and treat diseases in animals.
基金financially supported by the National Key R&D Program of China(Nos.2020YFA0908100 and 2023YFF1204401)Shenzhen Medical Research Fund(No.B2302037)+1 种基金the National Natural Science Foundation of China(Nos.22331003 and 21925102)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202006)。
文摘Thermophilic proteins maintain their structure and function at high temperatures,making them widely useful in industrial applications.Due to the complexity of experimental measurements,predicting the melting temperature(T_(m))of proteins has become a research hotspot.Previous methods rely on amino acid composition,physicochemical properties of proteins,and the optimal growth temperature(OGT)of hosts for T_(m)prediction.However,their performance in predicting T_(m)values for thermophilic proteins(T_(m)>60℃)are generally unsatisfactory due to data scarcity.Herein,we introduce T_(m)Pred,a T_(m)prediction model for thermophilic proteins,that combines protein language model,graph convolutional network and Graphormer module.For performance evaluation,T_(m)Pred achieves a root mean square error(RMSE)of 5.48℃,a pearson correlation coefficient(P)of 0.784,and a coefficient of determination(R~2)of 0.613,representing improvements of 19%,15%,and 32%,respectively,compared to the state-of-the-art predictive models like DeepTM.Furthermore,T_(m)Pred demonstrated strong generalization capability on independent blind test datasets.Overall,T_(m)Pred provides an effective tool for the mining and modification of thermophilic proteins by leveraging deep learning.
基金Project(50974140) supported by the National Natural Science Foundation of ChinaProject(20090162110054) supported by Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.
基金Projects(51374248,51320105006)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0595)supported by the Program for New Century Excellent Talents in University,ChinaProject(2014T70692)supported by China Postdoctoral Science Foundation
文摘X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.
基金Project (41271330) supported by the National Natural Science Foundation of China
文摘The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.
基金supported by the National High Technology Research and Development Program (Nos. 2012AA061501, 2012AA061502)the National Natural Science Foundation of China (No. 50934002)
文摘Bioleaching of chalcopyrite often encountered the formation of passivation layer, which inhibited the leaching process and resulted in a low leaching rate. This inhibitory effect can be eliminated by thermophilic biole- aching. The industrial test of BioCOP technology based on thermophiles was successfully completed, which confirmed the feasibility of chalcopyrite bioleaching. However, industrial leaching rate of chalcopyrite heap bioleaching is lower. This paper described the development status and industrial test of chalcopyrite heap bioleaching technology. The reasons for the lower efficiency of chalcopyrite heap bioleaching were analyzed. The strategies for successful chalcopyrite heap bioleaching were proposed.
基金The Key Natural Science Foundation of Fujian under contract No. 2007J0004the National Natural Science Foundation of China under contract No. 40576076
文摘Viruses of thermophiles are of great interest due to their roles in gene transfer, global geochemical cycle and evolution of life on earth. However, the thermophilic bacteriophages have not been studied extensively. In this investigation, a typical bacteriophage BV1 was obtained from a thermophilic bacterium Geobacillus sp. 6k512, which was isolated from an inshore hot spring in Xiamen of China. The BV1 contained a double-stranded linear DNA of 35 055 bp, which encodes 54 open reading frames （ORFs）. Interestingly, eight of the 54 BV1 ORFs shared sequence similarities to genes from human disease-relevant bacteria. Seven proteins of the purified BV1 virions were identified by proteomic analysis. Determination of BV1 functional genomics would facilitate the better understanding of the mechanism for virus-thermophile interaction.
基金support from ANPCy T (PICT 2012 0623 and PICT 2013 0630)
文摘The attachment and bioleaching experiments were conducted to evaluate the zinc recovery from Hualilan ore by thethermoacidophilic archaeon Acidianus copahuensis. Cells of this species pregrown on tetrathionate showed higher capability ofattachment to the ore than cells pregrown on other energy sources and such attachment seemed to be mediated by the product ofextracellular polymeric substances. A. copahuensis achieved a successful bioleaching of the ore reaching 100% of zinc recoverywhen tetrathionate was added. Simultaneous addition of yeast extract and tetrathionate maintained the zinc extraction at higher rate.Zinc dissolution kinetics was controlled by chemical reaction in cultures with the external addition of tetrathionate but by thediffusion through a product layer of jarosite in the other cultures.
文摘Acidogenic dissimilation of synthetic starch wastewater (1 000～10 000 mg COD·L -1 ) was studied in a thermophilic (55 ℃) upflow anaerobic sludge blanket (UASB) reactor.The production of volatile fatty acids (VFA) was proportional to the chemical oxygen demand (COD) loading rate.The yield of VFA was around 0.28 g VFA/g COD over the COD loading rate from 1.25 to 30 g COD·L -1 ·d -1 and the hydraulic retention time from 8.8 h to 24 h.Distribution of organic acids,the contents of propionic and butyric acids in the effluent in particular were also dependent on the COD loading rate.The thermophilic UASB reactor showed a stable performance on hydrolysis and acidogenesis of starch as well as suspended solid removal at short hydraulic retention times and high influent pH(10～11),during the operation of 110 d.
文摘[Objective] The aim was to study the physiological and biochemical char- acteristics of Thermoanaerobacter sp DF3 in petroleum reservoirs and optimize the culture plan of producing ethanol from xylose. [Method] DF3, an anaerobic bacillus producing ethanol, was isolated from produced liquid from oil layer of Dagang oil field with anaerobic isolation technique. The phylogenetic position was analyzed by physiological and biochemical identification and phylogeny of 16S rDNA sequence. The metabolites were analyzed by gas chromatograph. [Result] The strain DF3 was a strict anaerobic thermophilic bacterium, which was straight in rod shape,and gram negative. Besides, it was 0.42 μmx（1.60-5.20） iJm in length. The strains can be soli- tary,in pairs or string and apical spore usually produced. Its growth temperature was 45-78 and 65 ℃ was the optimum. Many substances could be used as carbon sources, including glucose, xylose, fructose, ribose, mannose, arabinose, sucrose, galactose, lactose, cellobiose, melizitose, raffinose-, and starch. The similarity between strain DF3 and T. pseudoethanolicus achieved 99.7%. The main product of glucose and xylose fermentation was ethanol. After the culture plan was optimized,the final concentration of ethanol was 2.0 g/L. [Conclusion] It was proved through experiments that the strain DF3 was one of the strains with higher activity to produce ethanol at present and it could produce 2.0 g/L ethanol from xylose metabolization at 65 ℃. It has been demonstrated that DF3 is one of the known strains with high-production to produce ethanol,for example, 2.0 g/L ethano at 65℃. Presently, all the high-yield ethanol can be produced from metabolic xylose strains of metabolic xylose were isolat- ed by foreign countries, therefore, isolation of strain DF3 has provided an excellent original strain for studying ethanol production from lignocellulose in China.
基金supported by the BioEnergy Science Center (BESC),which is a U.S. Department of Energy Bioenergy Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science
文摘Live cell imaging methods provide important insights into the dynamics of cellular processes that cannot be derived easily from population-averaged datasets.In the bioenergy field,much research is focused on fermentation of cellulosic biomass by thermophilic microbes to produce biofuels;however,little effort is dedicated to the development of imaging tools to monitor this dynamic biological process.This is,in part,due to the experimental challenges of imaging cells under both anaerobic and thermophilic conditions.Here an imaging system is described that integrates confocal microscopy,a flow cell device,and a lipophilic dye to visualize cells.Solutions to technical obstacles regarding suitable fluorescent markers,photodamage during imaging,and maintenance of environmental conditions during imaging are presented.This system was utilized to observe cellulose colonization by Clostridium thermocellum under anaerobic conditions at 60℃.This method enables live cell imaging of bacterial growth under anaerobic and thermophilic conditions and should be widely applicable to visualizing different cell types or processes in real time.
基金supported by INNOVA-CORFO 07CN13PXT-64Instituto Antártico Chileno (INACH)US Air Force Office of Scientific Research (AFOSR)
文摘Glutamate dehydrogenase （GDH） catalyzes the oxidative deamination of glutamate to a-ketoglutarate and ammonium ions. Currently the determination of ammonium and glutamate is carried out using a bovine GDH enzyme, which lacks optimal thermostability for long term storage at room temperature. From samples of Deception Island, Antarctica, we obtained the thermophilic bacteria PID 15 belonging to the Bacillus genera with high GDH specific activity. This new enzyme exhibited NAD＋ dependent activity and no activity was observed when NADP＋ was used. This enzyme shows a specific activity of 4.7 U.mg-1 for the oxidative deamination reaction and 15.4 U·mg-1 for the reduction of a-ketoglutarate. This enzyme has an optimum temperature of 65℃ and pH of 8.5 for the oxidative deamination. For the reduction of a-ketoglutarate, the optimum temperature is 60℃, with a pH of 8.0. One of the most important characteristics of this enzyme is its ability to retain more than 60% of its activity when it is incubated for 8 h at 65℃. The enzyme is also able to retain full activity when it is incubated for 48 d at 4℃ and over 80% of its activity when it is incubated at 25℃. Characterization of its kinetics suggests that it primarily catalyzes the formation of α-ketoglutarate. This enzyme has an important biological role in the catabolism of glutamate and may have some interesting biotechnological applications based on its thermostable properties.
文摘Thermoanaerobacterium thermosaccharolyticum shows promise as a host for n-butanol production since it natively has the required genes involved in the n-butanol biosynthetic pathway. Overexpression of the natively occurring bcs operon containing the genes thl, hbd, crt, bcd, etfA, and etfB responsible for the formation of butyryl CoA increased the n-butanol production by 180% compared to the wild type from a n-butanol titer of 1.8 mM to 5.1 mM. The deletion of one of the six alcohol dehydrogenase genes confirmed that it was the primary gene responsible for ethanol and n-butanol production from acetyl CoA and butyryl CoA respectively.
文摘Abundant virus-like particles were concentrated from large-volume samples from two hot springs. Both addition of viral concentrates and addition of samples induced by addition of mitomycin-C changed patterns of carbon source utilization by hot spring microbial communities. Specific effects of the two treatments depended upon both temperature and incubation period. Increased metabolic capability with greater exposure to free phages, consistent with the view that phages are major lateral transporters of metabolic genes, was observed most clearly in microbes incubated at a temperature lower than that encountered in situ. On the other hand, decreases in the diversity of utilizable C sources upon exposure to phages may have been due to lytic activity in which susceptible bacterial populations were differentially reduced by infective viruses, consistent with the “killing the winner” hypothesis. Treatment of cultures with MC-treated culture extracts, assumed to increase exposure to excised prophages, resulted in higher average metabolic rates after 18 h, but lower rates after 48 h of incubation. With incubation at in situ temperature, this same treatment led to an initial increase in the number of readily utilized C sources, followed by a decrease in community metabolic diversity relative to controls in samples from both hot springs. Thus, treatments designed to increase the interaction between hot spring microbes and either free or newly-excised phages had observable time- and temperature-dependent effects on community metabolism, demonstrating an important, yet complex, ecological role for phages in hot spring waters.
基金Project supported by the Grant-in-Aid for Science Research of Japan Society for the Promotion of Science (JSPS), Japan.
文摘Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e., β-glucosidase, N-α-benzoyl-Largininamide （BAA）-hydrolysing protease, urease and phosphatase activities were analysed. The BAA-hydrolysing protease activity during the first 2-3 weeks was low with low pH, but was enhanced later with the pH increase. β-Glucosidase activity showed the lowest values in weeks 1-2, and recovered with the increase of BAA-hydrolysing protease activity. Acetic acid dominated most of the total VFAs in thermophilic digestion, while propionate and butyrate dominated in mesophilic digestion. Thermophilic digestion was confirmed more feasible for achieving better performance against misbalance, especially during the start-up period in a dry anaerobic digestion process.
