The selection of carbon sources and the biosynthesis of polyhydroxybutyrate(PHB)by the Azotobacter vinelandii N-15 strain using renewable raw materials were investigated.Among the tested substrates(starch,sucrose,mola...The selection of carbon sources and the biosynthesis of polyhydroxybutyrate(PHB)by the Azotobacter vinelandii N-15 strain using renewable raw materials were investigated.Among the tested substrates(starch,sucrose,molasses,bran),molasses as the carbon source yielded the highest PHB production.The maximum polymer yield(26%of dry biomass)was achieved at a molasses concentration of 40 g/L.PHB formation was confirmed via thinlayer chromatography,gas chromatography and Fourier transform infrared spectroscopy.Composite films based on PHB,polylactic acid(PLA),and their blends were fabricated using the solvent casting.The biodegradation of these films was studied with bacteria isolated from plastic-contaminated soil.These bacteria utilized the biopolymers as their sole carbon source,with the biodegradation process lasting three months.Structural and chemical changes in the films were analyzed using FTIR spectroscopy,differential scanning calorimetry,and thermogravimetry.Among the microorganisms used to study the biodegradation of PHB,PLA,and their blends,Streptomyces sp.K2 and Streptomyces sp.K4 exhibited the highest biodegradation efficiency.PHB-containing films demonstrated significant advantages over other biodegradable polymers,as they degrade under aerobic conditions via enzymatic hydrolysis using microbial depolymerases.展开更多
An extracellular polyhydroxybutyrate（PHB） depolymerase was purified to homogeneity from the culture supernatant of a PHB-degrading bacterium, Pseudomonas mendocina DSWY0601, which was isolated from brewery sewage fo...An extracellular polyhydroxybutyrate（PHB） depolymerase was purified to homogeneity from the culture supernatant of a PHB-degrading bacterium, Pseudomonas mendocina DSWY0601, which was isolated from brewery sewage for the ability to form clear zones on the PHB mineral agar plates. The molecular weight of the purified PHB depolymerase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE） was ap- proximately 59800 at the optimal temperature and pH value being 50 ℃ and 8.5, respectively. PHB depolymerase was stable in a temperature range of 20--50 ℃ and sensitive to pH value within a pH range of 8.0-9.5. PHB depo- lymerase degraded poly-3-hydroxybutyrate-co-4-hydroxybutyrate（P3/4HB） and poly-3-hydroxybutyrate-co-3- hydroxyvalerate（PHBV） but did not degrade poly（lactic acid）（PLA）, poly（butylene succinate）（PBS） or poly- （caprolactone）（PCL）. PHB depolymerase was sensitive to phenylmethylsulfonyl fluoride（PMSF）, H202 and SDS. The main product after enzymatic degradation of PHB was indentified as 3-hydroxbutyrate monomer（3HB） by mass spectrometric analysis, suggesting that PHB depolymerase acted as an exo-type hydrolase. Analysis ofphaZpm gene reveals that PHB depolymerase is a typical denatured short-chain-length PHA（dPHAscL, PHA=polyhydroxyalkanoate） depolymerase containing catalytic domain, linker and substrate-binding domain.展开更多
The effects of different NaCl concentrations, nitrogen sources, carbon sources, and carbon to nitrogen molar ratios on biomass accumulation and polyhydroxybutyrate （PHB） production were studied in batch cultures of ...The effects of different NaCl concentrations, nitrogen sources, carbon sources, and carbon to nitrogen molar ratios on biomass accumulation and polyhydroxybutyrate （PHB） production were studied in batch cultures of the marine photosynthetic bacterium Rhodovulum sulfidophilum P5 under aerobic-dark conditions. The results show that the accumulation of PHB in strain P5 is a growth-associated process. Strain P5 had maximum biomass and PHB accumulation at 2%-3% NaCl, suggesting that the bacterium can maintain growth and potentially produce PHB at natural seawater salinity. In the nitrogen source test, the maximum biomass accumulation （8.10±0.09 g/L） and PHB production （1.11±0.13 g/L and 14.62%±2.25% of the cell dry weight） were observed when peptone and ammonium chloride were used as the sole nitrogen source. NH^-N was better for PHB production than other nitrogen sources. In the carbon source test, the maximum biomass concentration （7.65±0.05 g/L） was obtained with malic acid as the sole carbon source, whereas the maximum yield of PHB （5.03±0.18 g/L and 66.93%± 1.69% of the cell dry weight） was obtained with sodium pyruvate as the sole carbon source. In the carbon to nitrogen ratios test, sodium pyruvate and ammonium chloride were selected as the carbon and nitrogen sources, respectively. The best carbon to nitrogen molar ratio for biomass accumulation （8.77±0.58 g/L） and PHB production （6.07±0.25 g/L and 69.25%±2.05% of the cell dry weight） was 25. The results provide valuable data on the production of PHB by R. sulfidophilum P5 and further studies are on-going for best cell growth and PHB yield.展开更多
Polyhydroxyalkanoates（PHAs） are aliphatic polyesters accumulated intracellularly by both Gram-negative and Gram-positive bacteria. However, compared to the PHAs of Gramnegative bacteria, few endotoxins（lipopolysacc...Polyhydroxyalkanoates（PHAs） are aliphatic polyesters accumulated intracellularly by both Gram-negative and Gram-positive bacteria. However, compared to the PHAs of Gramnegative bacteria, few endotoxins（lipopolysaccharides, LPS）, which would be co-purified with PHAs and cause immunogenic reactions, are found in the PHAs produced by Gram-positive bacteria. A thermophilic Gram-positive bacterium K5, which exhibited good growth and polyhydroxybutyrate（PHB）-accumulating ability, has been isolated and characterized from a biotrickling filter designed for the removal of NOx from flue gas in a coal-fired power plant in China. Based on the biochemical characterization and 16 S rRNA gene sequence（Genbank accession no. JX437933）, the strain K5 has been identified as Bacillus shackletonii, which has rarely been reported in the literature, and this report is the first time that B. shackletonii has been found to accumulate PHB. The strain K5 was able to utilize glucose as carbon source to synthesize PHB at a broad range of temperatures（from 35 to 50 °C）, and the ideal temperature was 45 °C. The strain K5 could effectively yield PHB of up to 69.9% of its cell dry weight（CDW）（2.28 g/L） in flask experiments employing glucose as carbon source at 45 °C, followed by 56.8% and 52.3% of its CDW when using sodium succinate and glycerol as carbon source, respectively. For batch cultivation, the strain K5 was able to produce PHB of up to 72.6% of its cell dry weight（9.76 g/L） employing glucose as carbon source at 45 °C and pH 7.0.展开更多
The PHB （polyhydroxybutyrate） films were reported recently as promising materials for tissue involving cultivation of dermoblasts, fibroblasts and connective tissue. In the present work, the authors studied PHB scaf...The PHB （polyhydroxybutyrate） films were reported recently as promising materials for tissue involving cultivation of dermoblasts, fibroblasts and connective tissue. In the present work, the authors studied PHB scaffolds for the cardiac tissue engineering, either in a form of thin membranes or electrospun fiber mats. The results show that cardiac cells of various origins can be successfully grown on PHB substrates, in the both forms： membrane and nanofiber matrix. Functioning of obtained tissue patches was tested by visual observation of contractions and with the aid of optical mapping, i.e., registration of excitation waves with fluorescent markers. The latter one allowed ensuring the fact that cultured cells represented electrophysiological syncytium, and the PHB scaffold showed its full compatibility with the excitability of cardiac cells.展开更多
To further develop the tree peony(Paeonia ostii)industry,methods for reusing the peony pods were explored,which are only used as low-value firewood.in the study,pods were subjected to alkaline pretreatment to produce ...To further develop the tree peony(Paeonia ostii)industry,methods for reusing the peony pods were explored,which are only used as low-value firewood.in the study,pods were subjected to alkaline pretreatment to produce fermentable reducing sugar for polyhydroxybutyrate(PHb)production.Fourier transform infrared(Ftir)results and reducing sugar yields for samples subjected to alkaline pretreatment were better than those for untreated samples,and the reducing sugar yield increased by 27.15%.the degree of hydrolysis and reducing sugar yield were increased by optimizing enzymatic parameters.the produced reducing sugar had carbon and nitrogen content of 31.69%and 0.095%,respectively,and most carbon came from glucose and xylose.the reducing sugar was fermented using a recombinant Escherichia coli strain,and the product was confirmed to be PHb by Ftir and proton nuclear magnetic resonance(1H NMr)analyses.the PHb yield increased by 36.67%when the produced reducing sugar,instead of glucose,was used as the carbon source.Meanwhile,corn steep liquor increased PHb production more significantly than the other tested nitrogen sources.the results of the study can promote the further development of the tree peony industry for commercial biodegradable PHb production by providing economical biomass.展开更多
A procedure for transformation of intact Streptococcus zooepidemicus cells by electroporation was developed through a systematic examination of the effects of various parameters, including growth conditions, electr...A procedure for transformation of intact Streptococcus zooepidemicus cells by electroporation was developed through a systematic examination of the effects of various parameters, including growth conditions, electric field strengths used for electroporation, and concentrations of plasmid used for transformation. Efficiencies higher than 10 4 cfu/μg (cfu, clone forming unit) plasmid DNA were obtained for Streptococcus zooepidemicus H2004 cells. Results demonstrate that the broad host range plasmid pDL276 can be replicated in Streptococcus zooepidemicus H2004 and foreign genes responsible for polyhydroxybutyrate (PHB) synthesis inserted into the pDL276 can be successfully expressed in the transformant, in which PHB is detected using the Fourier transform infrared spectroscopy (FT IR) method.展开更多
Given the environmental pollution caused by petroleum-based plastics,finding alternative substitutes for sustainability has become critical.Polyhydroxybutyrate(PHB),a storage food material that is accumulated by sever...Given the environmental pollution caused by petroleum-based plastics,finding alternative substitutes for sustainability has become critical.Polyhydroxybutyrate(PHB),a storage food material that is accumulated by several bacteria,is biodegrad-able,safe,environment friendly and comparable to conventional plastics.However,scale-up is an issue due to high produc-tion cost.Substrate replacement using renewable,plentiful,sustainable and low-cost carbon sources derived from industrial waste facilitates waste reduction,while also enabling the synthesis of value-added products.In this context,inexpensive pulp and paper industrial waste as carbon source was exploited for production of PHB by using previously isolated(Source:hot springs of Manikarn,Himachal Pradesh,India)thermophilic bacteria Bacillus sonorensis NAM5 under optimized conditions in a fermenter.Production was done in a fermenter under optimized conditions(72 h of incubation at 50℃temperature and 7 pH)to enhance the accumulation of PHB.The bacterial strain was able to produce 5.28±0.11 gL^(-1)after 72 h of growth without any carbon and nitrogen source supplementation to the industrial effluent.The culture accumulated 66%PHB of cell dry weight(CDW).The produced polymer was characterized through FTIR,NMR and TGA.Additionally,bacteria-treated industrial wastewater was used for phytotoxicity assay on agriculturally important crops such as wheat,maize and mung,which exhibited considerable difference in growth parameters.展开更多
Nanotechnology and tissue engineering have accelerated wound healing.Polyhydroxyalkanoates,with suitable physical,biological and mechanical properties,can be considered as a good candidate in tissue repair and regener...Nanotechnology and tissue engineering have accelerated wound healing.Polyhydroxyalkanoates,with suitable physical,biological and mechanical properties,can be considered as a good candidate in tissue repair and regeneration.In this study,nanofibrous mats of polyhydroxybutyrate(PHB)containing curcumin as a wound healing agent,were designed by electrospinning method.The samples were evaluated by microscopic and mechanical analyses,cell assays and microbial tests.The results of microscopic images showed that the diameter of fibers increased with the increase in the curcumin concentration.The elongation and elasticity modulus of nanofibers increased and decreased respectively,with the increase in the amount of curcumin.Drug release study indicated that increasing the curcumin concentration into nanofibers accelerated rate of drug release.Cytotoxicity results of nanofibrous samples with lower curcumin showed better biocompatibility.The strongest antibacterial activity was shown by the sample with 3% curcumin.In addition,Curcumin-loaded nanofibrous PHB can be potential candidates for wound healing.展开更多
Many bacteria have been found to synthesize a family of polyesters termed polyhydroxyalkanoate, abbreviated as PHA. Some interesting physical properties of PHAs such as piezoelectricity, non-linear optical activity, b...Many bacteria have been found to synthesize a family of polyesters termed polyhydroxyalkanoate, abbreviated as PHA. Some interesting physical properties of PHAs such as piezoelectricity, non-linear optical activity, biocompatibility and biodegradability offer promising applications in areas such as degradable packaging, tissue engineering and drug delivery. Over 90 PHAs with various structure variations have been reported and the number is still increasing. The mechanical property of PHAs changes from brittle to flexible to elastic, depending on the side-chainlength of PHA. Many attempts have been made to produce PHAs as biodegradable plastics using various microorganisms obtained from screening natural environments, genetic engineering and mutation. Due to the high production cost, PHAs still can not compete with the nondegradable plastics, such as polyethylene and polypropylene. Various processes have been developed using low cost raw materials for fermentation and an inorganic extraction process for PHA purification. However, a super PHA production strain may play the most critical role for any large-scale PHA production. Our recent study showed that PHA synthesis is a common phenomenon among bacteria inhabiting various locations, especially oil-contaminated soils. This is very important for finding a suitable bacterial strain for PHA production. In fact, PHA production strains capable of rapid growth and rapid PHA synthesis on cheap molasses substrate have been found on molasses contaminated soils. A combination of novel properties and lower cost will allow easier commercialization of PHA for many applications.展开更多
Objective: To investigate the improved antitrypanocidal activity and toxicity of diminazene aceturate modified Nano drug in experimental rats. Methods: Aqueous leaf extract of Hyptis suaveolens was used to reduce gold...Objective: To investigate the improved antitrypanocidal activity and toxicity of diminazene aceturate modified Nano drug in experimental rats. Methods: Aqueous leaf extract of Hyptis suaveolens was used to reduce gold tetrachloride to its nanoparticle size and this was characterized and formulates with naturally synthesized polyhydroxybutyrateas a Nano carrier. A total of thirty (30) albino rats were group into 6 (A-F) of 5 rats each & infected intraperitoneally with 0.2 mL of the inoculum containing about 1×103 Trypanosoma brucei brucei parasites per 0.2 mL of blood. Groups A and B were treated with 3 and 6 minutes released orange PHB, Groups C and D were treated with 15 and 30 minutes released mango PHB formulated tablet while Groups E and F were negative (untreated) and standard drug (Dininazene aceturare) respectively. Results: The free drug and modified orange synthesized polyhydroxy butyrate shows antitrypanocidal activities by reducing the replicating rate of the parasite as compared to infect untreated. While the modified- mango synthesized shows increasing order of replication. There were significant increases in all the haematological parameter evaluated in the infected treated groups compared to infect untreated. But no significant difference (P<0.05) observed in the Catalase activity in the serum and liver of all the groups whereas, the modified orange synthesized shows significant decrease in other enzymes activities evaluated when compared with the free drug, mango synthesized and the infected untreated groups. Conclusion: Orange synthesized modified diminazene aceturate show efficacy as free drug with limited toxicity that can enhance the therapeutic.展开更多
Background:In the present study,we aim to utilize the ecological diversity of soil for the isolation and screening for polyβ-hydroxybutyrate(PHB)-accumulating bacteria and production of cost-effective bioplastic usin...Background:In the present study,we aim to utilize the ecological diversity of soil for the isolation and screening for polyβ-hydroxybutyrate(PHB)-accumulating bacteria and production of cost-effective bioplastic using cardboard industry effluent.Results:A total of 120 isolates were isolated from different soil samples and a total of 62 isolates showed positive results with Nile blue A staining,a specific dye for PHB granules and 27 isolates produced PHB using cardboard industry effluent.The selected isolate NA10 was identified as Bacillus sp.NA10 by studying its morphological,biochemical,and molecular characteristics.The growth pattern for the microorganism was studied by logistic model and exactly fitted in the model.A maximum cell dry weight(CDW)of 7.8 g l^(−1)with a PHB concentration of 5.202 g l^(−1)was obtained when batch cultivation was conducted at 37℃ for 72 h,and the PHB content was up to 66.6%and productivity was 0.072 g l^(−1)h^(−1)in 2.0 L fermentor.Chemical characterization of the extracted PHB was done by H1NMR,Fourier transform infrared spectroscopy(FTIR),thermal gravimetric analysis(TGA),Gas chromatography-mass spectrometry(GC-MS)analysis to determine the structure,melting point,and molecular mass of the purified PHB.The polymer sheet of extracted polymer was prepared by blending the polymer with starch for packaging applications.Conclusions:The isolate NA10 can be a good candidate for industrial production of PHB from cardboard industry waste water cost-effectively and ecofriendly.展开更多
The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composi...The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composition as well to the quantity of the substrates present in wastewater fraction. Three different wastewater fractions are obtained as： raw wastewater, dissolved wastewater （obtained with filtration using 0.45 μm filter）, and undissolved wastewater （i.e., infiltrate obtained by above filtration）. The ratio of P-release/CODtotal-consumption clearly inferred that undissolved wastewater possess very low value i.e., 0.0008 followed by raw wastewater 0.008 and dissolved wastewater 0.03. When this ratio was nearby 0.01, enhanced P-removal was observed. Moreover, the ratio of P-uptake to NO3^--N decomposition for raw wastewater was two times for dissolved wastewater. Interestingly, it was observed that the P-removal and denitrification depend not only on the dissolved substrates but also the undissolved substrates present in the wastewater. The result of the P-removal obtained with this S-DN-P process did not show a big difference of 36%, 34% and 30%, respectively, for raw, dissolved and undissolved wastewater.展开更多
Date palm pit(DPP)-filled poly(-hydroxybutyrate)(PHB)composites were prepared,evaluated,and characterized to determine their thermal insulation ability.Thermal conductivity values ranged between 0.086 and 0.100 W/(m&#...Date palm pit(DPP)-filled poly(-hydroxybutyrate)(PHB)composites were prepared,evaluated,and characterized to determine their thermal insulation ability.Thermal conductivity values ranged between 0.086 and 0.100 W/(m·K).At a maximum filler concentration(50%(w)),the specific heat capacity and thermal diffusivity were 1183 J/(kg·K)and 0.0689 mm^(2)/s,respec-tively.The DPP increased the thermal stability,and the highest compressive strength obtained was 80 MPa at 30%filler content.The PHB-DPP composites exhibited promising water absorption(less than 6%)and tensile strength(6-14 MPa).Date-pit-based PHB composites could be used in sustainable building engineering and cleaner production.展开更多
New composites prepared containing nanoscale hydroxyapatite or monetite uniformly distributed in a polyhydroxyalkanoate (polyhydroxybutyrate or polyhydroxybutyrate-hydroxyvalerate) matrix with mass fractions of 1%5...New composites prepared containing nanoscale hydroxyapatite or monetite uniformly distributed in a polyhydroxyalkanoate (polyhydroxybutyrate or polyhydroxybutyrate-hydroxyvalerate) matrix with mass fractions of 1%5% were then injected into dumb-like specimens. The results show that the tensile strength and the tensile modulus of the composites are improved. The microstructures of the composites were observed using transmission electron microscopy (TEM).展开更多
The increased global demand for plastic materials has led to severe plastic waste pollution,particularly to the marine environment.This critical issue affects both sea life and human beings since microplastics can ent...The increased global demand for plastic materials has led to severe plastic waste pollution,particularly to the marine environment.This critical issue affects both sea life and human beings since microplastics can enter the food chain and cause several health impacts.Plastic recycling,chemical treatments,incineration and landfill are apparently not the optimum solutions for reducing plastic pollution.Hence,this review presents two newly identified environmentally friendly approaches,plastic biodegradation and bioplastic production using algae,to solve the increased global plastic waste.Algae,particularly microalgae,can degrade the plastic materials through the toxins systems or enzymes synthesized by microalgae itself while using the plastic polymers as carbon sources.Utilizing algae for plastic biodegradation has been critically reviewed in this paper to demonstrate the mechanism and how microplastics affect the algae.On the other hand,algae-derived bioplastics have identical properties and characteristics as petroleum-based plastics,while remarkably being biodegradable in nature.This review provides new insights into different methods of producing algae-based bioplastics(e.g.,blending with other materials and genetic engineering),followed by the discussion on the challenges and further research direction to increase their commercial feasibility.展开更多
The management and recycling of plastic waste is a challenging global issue.Polyethylene terephthalate(PET),one of the most widely used synthetic plastics,can be hydrolyzed by a series of enzymes.However,upcycling the...The management and recycling of plastic waste is a challenging global issue.Polyethylene terephthalate(PET),one of the most widely used synthetic plastics,can be hydrolyzed by a series of enzymes.However,upcycling the resulting monomers is also a problem.In this study,we designed a co-cultivation system,in which PET degradation was coupled with polyhydroxybutyrate(PHB)production.First,PETase from Ideonalla sakaiensis was expressed in Yarrowia lipolytica Po1f with a signal peptide from lipase.The engineered PETase-producing Y.lipolytica was confirmed to hydrolyze bis(2-hydroxyethyl)terephthalate(BHET)and PET powder into the monomers terephthalate(TPA)and ethylene glycol(EG).Simultaneously,a TPA-degrading Pseudomonas stutzeri strain isolated from PET waste was transformed with a recombinant plasmid containing the phb CAB operon from Ralstonia eutropha,which encodes enzymes for the biosynthesis of PHB.The two co-cultivated engineered microbes could directly hydrolyze BHET to produce the bioplastic PHB in one fermentation step.During this process,5.16 g/L BHET was hydrolyzed in 12 h,and 3.66 wt%PHB(3.54 g/L cell dry weight)accumulated in 54 h.A total of 0.31g/L TPA was produced from the hydrolyzation of PET in 228 h.Although PHB could not be synthesized directly from PET because of the low hydrolyzing efficiency of PETase,this study provides a new strategy for the biodegradation and upcycling of PET waste by artificial microflora.展开更多
Many bacteria are able to synthesize polyhydroxyalkanoates, abbreviated as PHA, as carbon and energy storage compounds. PHA with over 90 different monomer structures has been reported and the number keeps increasing. ...Many bacteria are able to synthesize polyhydroxyalkanoates, abbreviated as PHA, as carbon and energy storage compounds. PHA with over 90 different monomer structures has been reported and the number keeps increasing. The piezoelectricity, non linear optical activity, biocompatibility and biodegradability of PHA have offered promising applications in areas such as tissue engineering, drug delivery, smart materials and degradable packaging. Various microorganisms obtained from nature, genetic engineering and mutations have been used for microbial production of PHA as biodegradable plastics. In fact, PHA synthesizing bacteria can be easily found in various locations, especially oil contaminated soils. Many bacterial strains possessing the ability to synthesize PHA with various monomers have been isolated from oil contaminated soils. In molasses contaminated soil, 40% of the isolated bacteria were capable of growing rapidly and synthesizing PHA at the same time. It seems that nature has provided endless numbers of novel PHA synthesizing strains.展开更多
Pseudomonas pseudoalcaligenes strain M1\|2 isolated from oil\|contaminated soil collected from an oilfield in northern China was found to be able to synthesize a blend of polyhydroxyalkanoates (PHAs) containing mono...Pseudomonas pseudoalcaligenes strain M1\|2 isolated from oil\|contaminated soil collected from an oilfield in northern China was found to be able to synthesize a blend of polyhydroxyalkanoates (PHAs) containing monomers of 3\|hydroxybutyrate (C4), 3\|hydroxyvalerate (C5), 3\|hydroxyheptanoate (C7), 3\|hydroxyoctanoate (C8), 3\|hydroxynonanoate (C9), 3\|hydroxydecanoate (C10) and 3\|hydroxydodecanoate (C12) from various carbon sources. The hydroxyalkanoate (HA) monomer composition varied both quantitatively and qualitatively, depending on the carbon sources used. The presence of octanoate in substrates of myristic acid or tridecanoate promoted the synthesis of HB monomer in the blend. Concentration of octanoate was also found to significantly affect the PHB content in the blend. A PHA biosynthesis pathway in Pseudomonas pseudoalcaligens M1\|2 was proposed.展开更多
基金financial support of this paper by the Ministry of Education and Science of Ukraine under grant(Biotherm/0124U000789).
文摘The selection of carbon sources and the biosynthesis of polyhydroxybutyrate(PHB)by the Azotobacter vinelandii N-15 strain using renewable raw materials were investigated.Among the tested substrates(starch,sucrose,molasses,bran),molasses as the carbon source yielded the highest PHB production.The maximum polymer yield(26%of dry biomass)was achieved at a molasses concentration of 40 g/L.PHB formation was confirmed via thinlayer chromatography,gas chromatography and Fourier transform infrared spectroscopy.Composite films based on PHB,polylactic acid(PLA),and their blends were fabricated using the solvent casting.The biodegradation of these films was studied with bacteria isolated from plastic-contaminated soil.These bacteria utilized the biopolymers as their sole carbon source,with the biodegradation process lasting three months.Structural and chemical changes in the films were analyzed using FTIR spectroscopy,differential scanning calorimetry,and thermogravimetry.Among the microorganisms used to study the biodegradation of PHB,PLA,and their blends,Streptomyces sp.K2 and Streptomyces sp.K4 exhibited the highest biodegradation efficiency.PHB-containing films demonstrated significant advantages over other biodegradable polymers,as they degrade under aerobic conditions via enzymatic hydrolysis using microbial depolymerases.
基金Supported by the National Natural Science Foundation of China (Nos.31100046,31100099)
文摘An extracellular polyhydroxybutyrate（PHB） depolymerase was purified to homogeneity from the culture supernatant of a PHB-degrading bacterium, Pseudomonas mendocina DSWY0601, which was isolated from brewery sewage for the ability to form clear zones on the PHB mineral agar plates. The molecular weight of the purified PHB depolymerase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE） was ap- proximately 59800 at the optimal temperature and pH value being 50 ℃ and 8.5, respectively. PHB depolymerase was stable in a temperature range of 20--50 ℃ and sensitive to pH value within a pH range of 8.0-9.5. PHB depo- lymerase degraded poly-3-hydroxybutyrate-co-4-hydroxybutyrate（P3/4HB） and poly-3-hydroxybutyrate-co-3- hydroxyvalerate（PHBV） but did not degrade poly（lactic acid）（PLA）, poly（butylene succinate）（PBS） or poly- （caprolactone）（PCL）. PHB depolymerase was sensitive to phenylmethylsulfonyl fluoride（PMSF）, H202 and SDS. The main product after enzymatic degradation of PHB was indentified as 3-hydroxbutyrate monomer（3HB） by mass spectrometric analysis, suggesting that PHB depolymerase acted as an exo-type hydrolase. Analysis ofphaZpm gene reveals that PHB depolymerase is a typical denatured short-chain-length PHA（dPHAscL, PHA=polyhydroxyalkanoate） depolymerase containing catalytic domain, linker and substrate-binding domain.
基金Supported by the National Natural Science Foundation of China (Nos.30830015, 40806063)the Key Natural Science Foundation of Tianjin,China (No. 12JC2DJC22200)+2 种基金the Natural Science Foundation of Guangxi,China (No. 1000050096)the Foundation of Tianjin Key Laboratory of Marine Resources and Chemistry (Tianjin University of Science & Technology) (No. 200913)the Introduced Talents Scientific Research Initiating Foundation of Tianjin University of Science and Technology (No.20100410)
文摘The effects of different NaCl concentrations, nitrogen sources, carbon sources, and carbon to nitrogen molar ratios on biomass accumulation and polyhydroxybutyrate （PHB） production were studied in batch cultures of the marine photosynthetic bacterium Rhodovulum sulfidophilum P5 under aerobic-dark conditions. The results show that the accumulation of PHB in strain P5 is a growth-associated process. Strain P5 had maximum biomass and PHB accumulation at 2%-3% NaCl, suggesting that the bacterium can maintain growth and potentially produce PHB at natural seawater salinity. In the nitrogen source test, the maximum biomass accumulation （8.10±0.09 g/L） and PHB production （1.11±0.13 g/L and 14.62%±2.25% of the cell dry weight） were observed when peptone and ammonium chloride were used as the sole nitrogen source. NH^-N was better for PHB production than other nitrogen sources. In the carbon source test, the maximum biomass concentration （7.65±0.05 g/L） was obtained with malic acid as the sole carbon source, whereas the maximum yield of PHB （5.03±0.18 g/L and 66.93%± 1.69% of the cell dry weight） was obtained with sodium pyruvate as the sole carbon source. In the carbon to nitrogen ratios test, sodium pyruvate and ammonium chloride were selected as the carbon and nitrogen sources, respectively. The best carbon to nitrogen molar ratio for biomass accumulation （8.77±0.58 g/L） and PHB production （6.07±0.25 g/L and 69.25%±2.05% of the cell dry weight） was 25. The results provide valuable data on the production of PHB by R. sulfidophilum P5 and further studies are on-going for best cell growth and PHB yield.
基金supported by the National Natural Science Foundation of China (No. 51378217, U1360101)the research Project of Guangdong Provincial Department of Science and Technology Department (No. 2012A010800006)the Guangdong Natural Science and Foundation (No. S2012020010887)
文摘Polyhydroxyalkanoates（PHAs） are aliphatic polyesters accumulated intracellularly by both Gram-negative and Gram-positive bacteria. However, compared to the PHAs of Gramnegative bacteria, few endotoxins（lipopolysaccharides, LPS）, which would be co-purified with PHAs and cause immunogenic reactions, are found in the PHAs produced by Gram-positive bacteria. A thermophilic Gram-positive bacterium K5, which exhibited good growth and polyhydroxybutyrate（PHB）-accumulating ability, has been isolated and characterized from a biotrickling filter designed for the removal of NOx from flue gas in a coal-fired power plant in China. Based on the biochemical characterization and 16 S rRNA gene sequence（Genbank accession no. JX437933）, the strain K5 has been identified as Bacillus shackletonii, which has rarely been reported in the literature, and this report is the first time that B. shackletonii has been found to accumulate PHB. The strain K5 was able to utilize glucose as carbon source to synthesize PHB at a broad range of temperatures（from 35 to 50 °C）, and the ideal temperature was 45 °C. The strain K5 could effectively yield PHB of up to 69.9% of its cell dry weight（CDW）（2.28 g/L） in flask experiments employing glucose as carbon source at 45 °C, followed by 56.8% and 52.3% of its CDW when using sodium succinate and glycerol as carbon source, respectively. For batch cultivation, the strain K5 was able to produce PHB of up to 72.6% of its cell dry weight（9.76 g/L） employing glucose as carbon source at 45 °C and pH 7.0.
文摘The PHB （polyhydroxybutyrate） films were reported recently as promising materials for tissue involving cultivation of dermoblasts, fibroblasts and connective tissue. In the present work, the authors studied PHB scaffolds for the cardiac tissue engineering, either in a form of thin membranes or electrospun fiber mats. The results show that cardiac cells of various origins can be successfully grown on PHB substrates, in the both forms： membrane and nanofiber matrix. Functioning of obtained tissue patches was tested by visual observation of contractions and with the aid of optical mapping, i.e., registration of excitation waves with fluorescent markers. The latter one allowed ensuring the fact that cultured cells represented electrophysiological syncytium, and the PHB scaffold showed its full compatibility with the excitability of cardiac cells.
基金supported by shandong Provincial Key research and Development Program(2017GSF216007)“Double Hundred”Program for Foreign Experts of shandong Province(WST2017004)。
文摘To further develop the tree peony(Paeonia ostii)industry,methods for reusing the peony pods were explored,which are only used as low-value firewood.in the study,pods were subjected to alkaline pretreatment to produce fermentable reducing sugar for polyhydroxybutyrate(PHb)production.Fourier transform infrared(Ftir)results and reducing sugar yields for samples subjected to alkaline pretreatment were better than those for untreated samples,and the reducing sugar yield increased by 27.15%.the degree of hydrolysis and reducing sugar yield were increased by optimizing enzymatic parameters.the produced reducing sugar had carbon and nitrogen content of 31.69%and 0.095%,respectively,and most carbon came from glucose and xylose.the reducing sugar was fermented using a recombinant Escherichia coli strain,and the product was confirmed to be PHb by Ftir and proton nuclear magnetic resonance(1H NMr)analyses.the PHb yield increased by 36.67%when the produced reducing sugar,instead of glucose,was used as the carbon source.Meanwhile,corn steep liquor increased PHb production more significantly than the other tested nitrogen sources.the results of the study can promote the further development of the tree peony industry for commercial biodegradable PHb production by providing economical biomass.
文摘A procedure for transformation of intact Streptococcus zooepidemicus cells by electroporation was developed through a systematic examination of the effects of various parameters, including growth conditions, electric field strengths used for electroporation, and concentrations of plasmid used for transformation. Efficiencies higher than 10 4 cfu/μg (cfu, clone forming unit) plasmid DNA were obtained for Streptococcus zooepidemicus H2004 cells. Results demonstrate that the broad host range plasmid pDL276 can be replicated in Streptococcus zooepidemicus H2004 and foreign genes responsible for polyhydroxybutyrate (PHB) synthesis inserted into the pDL276 can be successfully expressed in the transformant, in which PHB is detected using the Fourier transform infrared spectroscopy (FT IR) method.
文摘Given the environmental pollution caused by petroleum-based plastics,finding alternative substitutes for sustainability has become critical.Polyhydroxybutyrate(PHB),a storage food material that is accumulated by several bacteria,is biodegrad-able,safe,environment friendly and comparable to conventional plastics.However,scale-up is an issue due to high produc-tion cost.Substrate replacement using renewable,plentiful,sustainable and low-cost carbon sources derived from industrial waste facilitates waste reduction,while also enabling the synthesis of value-added products.In this context,inexpensive pulp and paper industrial waste as carbon source was exploited for production of PHB by using previously isolated(Source:hot springs of Manikarn,Himachal Pradesh,India)thermophilic bacteria Bacillus sonorensis NAM5 under optimized conditions in a fermenter.Production was done in a fermenter under optimized conditions(72 h of incubation at 50℃temperature and 7 pH)to enhance the accumulation of PHB.The bacterial strain was able to produce 5.28±0.11 gL^(-1)after 72 h of growth without any carbon and nitrogen source supplementation to the industrial effluent.The culture accumulated 66%PHB of cell dry weight(CDW).The produced polymer was characterized through FTIR,NMR and TGA.Additionally,bacteria-treated industrial wastewater was used for phytotoxicity assay on agriculturally important crops such as wheat,maize and mung,which exhibited considerable difference in growth parameters.
文摘Nanotechnology and tissue engineering have accelerated wound healing.Polyhydroxyalkanoates,with suitable physical,biological and mechanical properties,can be considered as a good candidate in tissue repair and regeneration.In this study,nanofibrous mats of polyhydroxybutyrate(PHB)containing curcumin as a wound healing agent,were designed by electrospinning method.The samples were evaluated by microscopic and mechanical analyses,cell assays and microbial tests.The results of microscopic images showed that the diameter of fibers increased with the increase in the curcumin concentration.The elongation and elasticity modulus of nanofibers increased and decreased respectively,with the increase in the amount of curcumin.Drug release study indicated that increasing the curcumin concentration into nanofibers accelerated rate of drug release.Cytotoxicity results of nanofibrous samples with lower curcumin showed better biocompatibility.The strongest antibacterial activity was shown by the sample with 3% curcumin.In addition,Curcumin-loaded nanofibrous PHB can be potential candidates for wound healing.
基金Tsinghua University 985 Project Fund and The State 95 Key Research and Development Fund and Hong Kong Polytechnic University contributed to this project.
文摘Many bacteria have been found to synthesize a family of polyesters termed polyhydroxyalkanoate, abbreviated as PHA. Some interesting physical properties of PHAs such as piezoelectricity, non-linear optical activity, biocompatibility and biodegradability offer promising applications in areas such as degradable packaging, tissue engineering and drug delivery. Over 90 PHAs with various structure variations have been reported and the number is still increasing. The mechanical property of PHAs changes from brittle to flexible to elastic, depending on the side-chainlength of PHA. Many attempts have been made to produce PHAs as biodegradable plastics using various microorganisms obtained from screening natural environments, genetic engineering and mutation. Due to the high production cost, PHAs still can not compete with the nondegradable plastics, such as polyethylene and polypropylene. Various processes have been developed using low cost raw materials for fermentation and an inorganic extraction process for PHA purification. However, a super PHA production strain may play the most critical role for any large-scale PHA production. Our recent study showed that PHA synthesis is a common phenomenon among bacteria inhabiting various locations, especially oil-contaminated soils. This is very important for finding a suitable bacterial strain for PHA production. In fact, PHA production strains capable of rapid growth and rapid PHA synthesis on cheap molasses substrate have been found on molasses contaminated soils. A combination of novel properties and lower cost will allow easier commercialization of PHA for many applications.
文摘Objective: To investigate the improved antitrypanocidal activity and toxicity of diminazene aceturate modified Nano drug in experimental rats. Methods: Aqueous leaf extract of Hyptis suaveolens was used to reduce gold tetrachloride to its nanoparticle size and this was characterized and formulates with naturally synthesized polyhydroxybutyrateas a Nano carrier. A total of thirty (30) albino rats were group into 6 (A-F) of 5 rats each & infected intraperitoneally with 0.2 mL of the inoculum containing about 1×103 Trypanosoma brucei brucei parasites per 0.2 mL of blood. Groups A and B were treated with 3 and 6 minutes released orange PHB, Groups C and D were treated with 15 and 30 minutes released mango PHB formulated tablet while Groups E and F were negative (untreated) and standard drug (Dininazene aceturare) respectively. Results: The free drug and modified orange synthesized polyhydroxy butyrate shows antitrypanocidal activities by reducing the replicating rate of the parasite as compared to infect untreated. While the modified- mango synthesized shows increasing order of replication. There were significant increases in all the haematological parameter evaluated in the infected treated groups compared to infect untreated. But no significant difference (P<0.05) observed in the Catalase activity in the serum and liver of all the groups whereas, the modified orange synthesized shows significant decrease in other enzymes activities evaluated when compared with the free drug, mango synthesized and the infected untreated groups. Conclusion: Orange synthesized modified diminazene aceturate show efficacy as free drug with limited toxicity that can enhance the therapeutic.
文摘Background:In the present study,we aim to utilize the ecological diversity of soil for the isolation and screening for polyβ-hydroxybutyrate(PHB)-accumulating bacteria and production of cost-effective bioplastic using cardboard industry effluent.Results:A total of 120 isolates were isolated from different soil samples and a total of 62 isolates showed positive results with Nile blue A staining,a specific dye for PHB granules and 27 isolates produced PHB using cardboard industry effluent.The selected isolate NA10 was identified as Bacillus sp.NA10 by studying its morphological,biochemical,and molecular characteristics.The growth pattern for the microorganism was studied by logistic model and exactly fitted in the model.A maximum cell dry weight(CDW)of 7.8 g l^(−1)with a PHB concentration of 5.202 g l^(−1)was obtained when batch cultivation was conducted at 37℃ for 72 h,and the PHB content was up to 66.6%and productivity was 0.072 g l^(−1)h^(−1)in 2.0 L fermentor.Chemical characterization of the extracted PHB was done by H1NMR,Fourier transform infrared spectroscopy(FTIR),thermal gravimetric analysis(TGA),Gas chromatography-mass spectrometry(GC-MS)analysis to determine the structure,melting point,and molecular mass of the purified PHB.The polymer sheet of extracted polymer was prepared by blending the polymer with starch for packaging applications.Conclusions:The isolate NA10 can be a good candidate for industrial production of PHB from cardboard industry waste water cost-effectively and ecofriendly.
基金supported by the KoreaScience and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (No. 2009-0078010)
文摘The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composition as well to the quantity of the substrates present in wastewater fraction. Three different wastewater fractions are obtained as： raw wastewater, dissolved wastewater （obtained with filtration using 0.45 μm filter）, and undissolved wastewater （i.e., infiltrate obtained by above filtration）. The ratio of P-release/CODtotal-consumption clearly inferred that undissolved wastewater possess very low value i.e., 0.0008 followed by raw wastewater 0.008 and dissolved wastewater 0.03. When this ratio was nearby 0.01, enhanced P-removal was observed. Moreover, the ratio of P-uptake to NO3^--N decomposition for raw wastewater was two times for dissolved wastewater. Interestingly, it was observed that the P-removal and denitrification depend not only on the dissolved substrates but also the undissolved substrates present in the wastewater. The result of the P-removal obtained with this S-DN-P process did not show a big difference of 36%, 34% and 30%, respectively, for raw, dissolved and undissolved wastewater.
基金financially supported by UAE University (SURE+2022 Grant#G00003848).
文摘Date palm pit(DPP)-filled poly(-hydroxybutyrate)(PHB)composites were prepared,evaluated,and characterized to determine their thermal insulation ability.Thermal conductivity values ranged between 0.086 and 0.100 W/(m·K).At a maximum filler concentration(50%(w)),the specific heat capacity and thermal diffusivity were 1183 J/(kg·K)and 0.0689 mm^(2)/s,respec-tively.The DPP increased the thermal stability,and the highest compressive strength obtained was 80 MPa at 30%filler content.The PHB-DPP composites exhibited promising water absorption(less than 6%)and tensile strength(6-14 MPa).Date-pit-based PHB composites could be used in sustainable building engineering and cleaner production.
基金Supported by the Major Research Project of the Ninth-Five Plan of China(No. 96- C0 3 - 0 3 - 0 2)
文摘New composites prepared containing nanoscale hydroxyapatite or monetite uniformly distributed in a polyhydroxyalkanoate (polyhydroxybutyrate or polyhydroxybutyrate-hydroxyvalerate) matrix with mass fractions of 1%5% were then injected into dumb-like specimens. The results show that the tensile strength and the tensile modulus of the composites are improved. The microstructures of the composites were observed using transmission electron microscopy (TEM).
文摘The increased global demand for plastic materials has led to severe plastic waste pollution,particularly to the marine environment.This critical issue affects both sea life and human beings since microplastics can enter the food chain and cause several health impacts.Plastic recycling,chemical treatments,incineration and landfill are apparently not the optimum solutions for reducing plastic pollution.Hence,this review presents two newly identified environmentally friendly approaches,plastic biodegradation and bioplastic production using algae,to solve the increased global plastic waste.Algae,particularly microalgae,can degrade the plastic materials through the toxins systems or enzymes synthesized by microalgae itself while using the plastic polymers as carbon sources.Utilizing algae for plastic biodegradation has been critically reviewed in this paper to demonstrate the mechanism and how microplastics affect the algae.On the other hand,algae-derived bioplastics have identical properties and characteristics as petroleum-based plastics,while remarkably being biodegradable in nature.This review provides new insights into different methods of producing algae-based bioplastics(e.g.,blending with other materials and genetic engineering),followed by the discussion on the challenges and further research direction to increase their commercial feasibility.
基金funding from the National Natural Science Foundation of China(grant numbers:Institute of Microbiology,Chi-nese Academy of Sciences:31961133016Beijing Institute of Technol-ogy:31961133015Shandong University:31961133014)and the Na-tional Key Research and Development Program of China(grant num-ber:2019YFA0706900)and was supported by European Union’s Hori-zon 2020 research and innovation programme under grant agreement No.870292(BIOICEP).
文摘The management and recycling of plastic waste is a challenging global issue.Polyethylene terephthalate(PET),one of the most widely used synthetic plastics,can be hydrolyzed by a series of enzymes.However,upcycling the resulting monomers is also a problem.In this study,we designed a co-cultivation system,in which PET degradation was coupled with polyhydroxybutyrate(PHB)production.First,PETase from Ideonalla sakaiensis was expressed in Yarrowia lipolytica Po1f with a signal peptide from lipase.The engineered PETase-producing Y.lipolytica was confirmed to hydrolyze bis(2-hydroxyethyl)terephthalate(BHET)and PET powder into the monomers terephthalate(TPA)and ethylene glycol(EG).Simultaneously,a TPA-degrading Pseudomonas stutzeri strain isolated from PET waste was transformed with a recombinant plasmid containing the phb CAB operon from Ralstonia eutropha,which encodes enzymes for the biosynthesis of PHB.The two co-cultivated engineered microbes could directly hydrolyze BHET to produce the bioplastic PHB in one fermentation step.During this process,5.16 g/L BHET was hydrolyzed in 12 h,and 3.66 wt%PHB(3.54 g/L cell dry weight)accumulated in 54 h.A total of 0.31g/L TPA was produced from the hydrolyzation of PET in 228 h.Although PHB could not be synthesized directly from PET because of the low hydrolyzing efficiency of PETase,this study provides a new strategy for the biodegradation and upcycling of PET waste by artificial microflora.
基金the Major Research Project of the Ninth-Five Plan(1996 2 0 0 0 ) of China(No.96 - C0 3- 0 3- 0 2 ) Tsinghua U niversity"985" Project
文摘Many bacteria are able to synthesize polyhydroxyalkanoates, abbreviated as PHA, as carbon and energy storage compounds. PHA with over 90 different monomer structures has been reported and the number keeps increasing. The piezoelectricity, non linear optical activity, biocompatibility and biodegradability of PHA have offered promising applications in areas such as tissue engineering, drug delivery, smart materials and degradable packaging. Various microorganisms obtained from nature, genetic engineering and mutations have been used for microbial production of PHA as biodegradable plastics. In fact, PHA synthesizing bacteria can be easily found in various locations, especially oil contaminated soils. Many bacterial strains possessing the ability to synthesize PHA with various monomers have been isolated from oil contaminated soils. In molasses contaminated soil, 40% of the isolated bacteria were capable of growing rapidly and synthesizing PHA at the same time. It seems that nature has provided endless numbers of novel PHA synthesizing strains.
基金the Trans-Century Training Pro gramme Foundation for Talent by the Ministry of Education of China and the Major Research
文摘Pseudomonas pseudoalcaligenes strain M1\|2 isolated from oil\|contaminated soil collected from an oilfield in northern China was found to be able to synthesize a blend of polyhydroxyalkanoates (PHAs) containing monomers of 3\|hydroxybutyrate (C4), 3\|hydroxyvalerate (C5), 3\|hydroxyheptanoate (C7), 3\|hydroxyoctanoate (C8), 3\|hydroxynonanoate (C9), 3\|hydroxydecanoate (C10) and 3\|hydroxydodecanoate (C12) from various carbon sources. The hydroxyalkanoate (HA) monomer composition varied both quantitatively and qualitatively, depending on the carbon sources used. The presence of octanoate in substrates of myristic acid or tridecanoate promoted the synthesis of HB monomer in the blend. Concentration of octanoate was also found to significantly affect the PHB content in the blend. A PHA biosynthesis pathway in Pseudomonas pseudoalcaligens M1\|2 was proposed.
