Synthetic biology(SynBio)is an emerging field of study with great potential in designing,engineering,and constructing new microbial synthetic cells that do not pre-exist in nature or re-engineering existing cells to a...Synthetic biology(SynBio)is an emerging field of study with great potential in designing,engineering,and constructing new microbial synthetic cells that do not pre-exist in nature or re-engineering existing cells to accomplish industrial purposes.Systems biology seeks to understand biology at multiple dimensions,beginning with the molecular and cellular level and progressing to the tissues and organismal level and characterizes cells as complex information-processing systems.SynBio,on the other hand,toggles further and strives to develop and create its systems from scratch.SynBio is now applied in the development of novel therapeutic drugs for the prevention of human diseases,scale up industrial processes,and accomplish previously unfeasible industrial outcomes.This is made possible through significant breakthroughs in DNA sequencing and synthesis technology,as well as insights gained from synthetic chemistry and systems biology.SynBio technologies have allowed for the introduction of improved and synthetic metabolic functionalities in microorganisms to enable the synthesis of a range of pharmacologically-relevant compounds for pharmaceutical exploration.SynBio applications range from finding new ways to making industrial chemical synthesis processes more sustainable as well as the microbial synthesis of improved therapeutic modalities.Hence,this study underpins several innovations,auspicious potentials,and future directions afforded by SynBio that proposes improved industrial microbial synthesis for pharmaceutical exploration.展开更多
Developing highly efficient and stable platinum-based electrocatalyst for oxygen reduction reaction(ORR) is critical to expediting commercialization of fuel cells.Herein,several PtCu alloy nanocatalysts supported on N...Developing highly efficient and stable platinum-based electrocatalyst for oxygen reduction reaction(ORR) is critical to expediting commercialization of fuel cells.Herein,several PtCu alloy nanocatalysts supported on N,P co-doped carbon(PtCu/NPC) were prepared by microbial-sorption and carbonization-reduction.Among them,PtCu/NPC-700 ℃ exhibits excellent catalytic performance for ORR with a mass activity of 0.895 A mg_(pt)^(-1)(@0.9 V) which is 8.29 folds of commercial Pt/C.Additionally,the ECSA and MA of PtCu/NPC-700℃ only decrease by 14.2% and 18.7% respectively,while Pt/C decreases by 35.2% and 52.8% after 10,000 cycles of ADT test.Moreover,the PtCu/NPC-700℃ catalyst emanates a maximum power density of 715 mW cm^(-2) and only 11.1% loss of maximum power density after 10,000 ADTs in single-cell test,indicating PtCu/NPC-700℃ also manifests higher activity and durability in actual single-cell operation than Pt/C.This research provides an easy and novel strategy for developing highly active and durable Pt-based alloy catalyst.展开更多
Microbial fabrication of metal nanoparticles(MNPs)has received significant attention due to the advantages of low toxicity,energy efficiency and ecological safety.Diverse groups of MNPs can be synthesized intracellula...Microbial fabrication of metal nanoparticles(MNPs)has received significant attention due to the advantages of low toxicity,energy efficiency and ecological safety.Diverse groups of MNPs can be synthesized intracellularly or extracellularly by various wild-type microorganisms,including bacteria,fungi,algae and viruses.Synthetic biology approaches,represented by genetic engineering,have been applied to overcome the shortcomings in productivity,stability,and controllability of biosynthetic MNPs.Scanning electron microscope(SEM),transmission electron microscope(TEM)and other characterization techniques assist in deciphering their unique properties.In addition,biosynthetic MNPs have been widely explored for the utilization in environmental remediation and contaminant detection.And machine learning contains a great potential for designing targeted MNPs and predicting their toxicity.This review provides a comprehensive overview of the research progress in the microbial synthesis of MNPs.An outlook on the current challenges and future prospects in the biologically controllable synthesis and engineering environmental applications of MNPs is also provided in this review.展开更多
Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles.The experimental condi...Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles.The experimental conditions of gold and silver nanoparticles production by the cells of studied strains in aqueous chloroauric acid(HAuCIq)and in silver nitrate(AgNO3)solutions,respectively,were determined.Concentration and time-dependences of nanoparticle formation were investigated.The complex of optical and analytical methods was used for testing the gold and silver nanoparticles in the bacterial biomass.The TEM(Transmission Electron Microscopy)and XRD(X-ray Diffraction)data in all cases demonstrated the presence of crystals with fcc(face centered cubic)structure.The results obtained show that the Actinomycetes are capable of producing gold and silver nanoparticles of spherical shape extracellularly when exposed to suitable compounds.The particle size distribution shows that the sizes of nanoparticles are in the range of 5 nm to 80 nm.The biomass obtained may be used for industrial as well as medical and pharmaceutical purposes.展开更多
Terpenoids,known for their structural and functional diversity,are highly valued,especially in food,cosmetics,and cleaning products.Microbial biosynthesis has emerged as a sustainable and environmentally friendly appr...Terpenoids,known for their structural and functional diversity,are highly valued,especially in food,cosmetics,and cleaning products.Microbial biosynthesis has emerged as a sustainable and environmentally friendly approach for the production of terpenoids.However,the natural enzymes involved in the synthesis of terpenoids have problems such as low activity,poor specificity,and insufficient stability,which limit the biosynthesis efficiency.Enzyme engineering plays a pivotal role in the microbial synthesis of terpenoids.By modifying the structures and functions of key enzymes,researchers have significantly improved the catalytic activity,specificity,and stability of enzymes related to terpenoid synthesis,providing strong support for the sustainable production of terpenoids.This article reviews the strategies for the modification of key enzymes in microbial synthesis of terpenoids,including improving enzyme activity and stability,changing specificity,and promoting mass transfer through multi-enzyme collaboration.Additionally,this article looks forward to the challenges and development directions of enzyme engineering in the microbial synthesis of terpenoids.展开更多
Cytochalasans are a class of hybrid polyketide-peptide natural products with diverse activities,including anti-tumor,anti-fungal,anti-parasitic,and anti-HIV properties,demonstrating significant application potential a...Cytochalasans are a class of hybrid polyketide-peptide natural products with diverse activities,including anti-tumor,anti-fungal,anti-parasitic,and anti-HIV properties,demonstrating significant application potential and broad market prospects.With the development of microbial metabolic engineering and synthetic biology,microbial synthesis of cytochalasans has emerged as a cost-effective and efficient alternative to traditional extraction and chemical synthesis methods,facilitating green and sustainable production.To better understand and promote the efficient heterologous biosynthesis of cytocha lasans,this review systematically summarizes and discusses the research progress on the biosynthesis of cytochalasans.Firstly,an overview of the classification,application and biological activity of cytochalasans is provided.Subsequently,we systematically review the relevant gene clusters,enzymes,and biosynthetic pathways involved in the biosynthesis of cytochalasans.Additionally,the latest progress in the design of microbial cell factories for producing cytochalasans and the strategies to enhance their performance are summarized and discussed.Finally,the current challenges in developing efficient cell factories for producing cytochalasans with renewable biomass as a substrate and the corresponding strategies are proposed,aiming to achieve higher-efficiency green biomanufacturing of cytochalasans.展开更多
Both enantiomers of fluoxetine were synthesized in five steps from ethyl benzoylacetate (1)using microbial-chemical approach with overall yields of 59% and 62% respectively.(S)-Enan- tiomer can be obtained in >99% ...Both enantiomers of fluoxetine were synthesized in five steps from ethyl benzoylacetate (1)using microbial-chemical approach with overall yields of 59% and 62% respectively.(S)-Enan- tiomer can be obtained in >99% e.e.by resting cell of baker's yeast and the R form was produced in 81 % e.e.by immobilized Geotrichum sp.G 38.展开更多
Verbascoside,which was first discovered in 1963,is a well-known phenylethanoid glycoside(PhG)that exhibits antioxidant,anti-inflammatory,antimicrobial,and neuroprotective activities and contributes to the therapeutic ...Verbascoside,which was first discovered in 1963,is a well-known phenylethanoid glycoside(PhG)that exhibits antioxidant,anti-inflammatory,antimicrobial,and neuroprotective activities and contributes to the therapeutic effects of many medicinal plants.However,the biosynthetic pathway of verbascoside remains to be fully elucidated.Here,we report the identification of two missing enzymes in the verbascoside biosynthesis pathway by transcriptome mining and in vitro enzymatic assays.Specifically,a BAHD acyltransferase(hydroxycinnamoyl-CoA:salidroside hydroxycinnamoyltransferase[SHCT])was shown to catalyze the regioselective acylation of salidroside to form osmanthuside A,and a CYP98 hydroxylase(osmanthuside B 3,30-hydroxylase[OBH])was shown to catalyze meta-hydroxylations of the p-coumaroyl and tyrosol moieties of osmanthuside B to complete the biosynthesis of verbascoside.Because SHCTs and OBHs are found in many Lamiales species that produce verbascoside,this pathway may be general.The findings from the study provide novel insights into the formation of caffeoyl and hydroxytyrosol moieties in natural product biosynthetic pathways.In addition,with the newly acquired enzymes,we achieved heterologous production of osmanthuside B,verbascoside,and ligupurpuroside B in Escherichia coli;this work lays a foundation for sustainable production of verbascoside and other PhGs in micro-organisms.展开更多
Microbial synthesis utilizes sustainable resources to produce valuable chemicals,as a potential alternative to petroleum-based chemical industry.Although metabolic engineering is an efficient method to enhance the bio...Microbial synthesis utilizes sustainable resources to produce valuable chemicals,as a potential alternative to petroleum-based chemical industry.Although metabolic engineering is an efficient method to enhance the biosynthesis efficacy of microorganisms,it requires complicated biological procedures.Herein,we report a facile intracellular catalysis system for augmenting the production of bio-based material in microorganism.Covalent linking of oligo(p-phenylenevinylene)(OPV)and cyclopentadienyl rhodium(Ⅲ)bipyridine offers intracellular metal catalyst(OPV-Rh).The OPV-Rh complex displayed certain resistance to toxic biomolecules,which guaranteed its catalytic activity in complicated biological systems.With uptake by Gramnegative bacterium Ralstonia eutropha H16(R.eutropha H16),the OPV-Rh complex promotes the transformation of intracellular NADP+to NADPH,which further enhances the biosynthesis of polyhydroxybutyrate(PHB)by this microorganism.This work demonstrates that synthetic metal catalyst can be employed for regulating microbial biosynthesis intracellularly.展开更多
Polyhydroxyalkanoates （PHAs） are a class of natural biopolyesters accumulated intracellularly by many microorganisms. These polymers have attracted particular attention as green plastic in biomedical and industrial ...Polyhydroxyalkanoates （PHAs） are a class of natural biopolyesters accumulated intracellularly by many microorganisms. These polymers have attracted particular attention as green plastic in biomedical and industrial applications due to their good biodegradability and bio- compatibility. Poly（3-hydroxybutyrate-co-3-hydroxyvaler- ate） （PHBV） is one of the most common members of PHAs. However, there is no report comparing the properties of PHBV from different groups of producers, e.g., bacteria and haloarchaea. In this study, two types of PHBV copolymers were synthesized in Halogranum amylolyticum and Ralstonia eutropha, respectively, by feeding different carbon sources. They possessed a similar concentration of 3HV monomers （21 tool%） and were named PHBV-H （produced by H. arnylolyticum） and PHBV-B （produced by R. eutropha） based on their source. Interestingly, they exhibited different behaviors especially in thermal stabil- ity, melting temperature, crystallinity percentage, and mechanical properties. Furthermore, the films of PHBV-Hand PHBV-B possessed different surface properties, such as surface roughness, wettability, and surface free energy. The value of hemolysis on the PHBV-H film was lower in comparison with the PHBV-B film, although both values were within the limit of 5 % permissible for biomaterials. Notably, few inactivated platelets adhered to the surface of the PHBV-H film, whereas numerous activated platelets were seen on film PHBV-B. These results indicated that PHBV-H was a better potential component of blood-contact biomaterials than PHBV-B. Our study clearly revealed that the properties of PHAs are source dependent and haloarchaeal species provide a new opportunity for the production of desired PHAs.展开更多
A simple and reproducible biosynthetic method was employed to synthesize iron and silver nanoparticles which resulted in monodispersed nanoparticles of high concentration.The iron oxide nanoparticles has been widely f...A simple and reproducible biosynthetic method was employed to synthesize iron and silver nanoparticles which resulted in monodispersed nanoparticles of high concentration.The iron oxide nanoparticles has been widely favored because of low cytotoxicity,biodegradable and reactive surface that can be modified with biocompatible coatings.Silver nanoparticles have been a potent antibacterial,antifungal,anti-viral and anti-inflammatory agent.The reaction process was simple,eco-friendly,inexpensive and easy to handle.Green and chemical methods were employed to synthesize iron and silver nanoparticles.A microbial route to synthesize iron and silver nanoparticles by the fungal strain Fusarium oxysporum sp.and Actinomycetes sp.was done simultaneously.Production of nanoparticles using fungi has some advantages over other organisms as it is easy to handle and require simple raw materials.The obtained iron and silver nanoparticles were characterized by UV-vis spectroscopy,Fourier transform infrared spectroscopy(FTIR)and the morphology of prepared nanoparticles was confirmed by Transmission electron microscopy(TEM).TEM images of Iron nanoparticles synthesized by Fusarium oxysporum sp.showed 20-40 nm sized particles.These particles exhibited maximum antibacterial activity against Bacillus,E.coli and Staphylococcus sps.TEM images of biosynthesized silver nanoparticles were of smaller size(10-20 nm).The microbially synthesized silver nanoparticles using Actinomycetes were found to be highly toxic against different human pathogens due to the smaller size and due to the presence of antibiotic components available on them.The mechanism of antimicrobial property of nanoparticle lies with the fact that the extremely small size means a large surface area relative to the volume,which effectively covers the microorganisms and reduce oxygen supply for respiration.It was found that silver nanoparticles synthesized by the microbial route have a greater antibacterial activity.展开更多
文摘Synthetic biology(SynBio)is an emerging field of study with great potential in designing,engineering,and constructing new microbial synthetic cells that do not pre-exist in nature or re-engineering existing cells to accomplish industrial purposes.Systems biology seeks to understand biology at multiple dimensions,beginning with the molecular and cellular level and progressing to the tissues and organismal level and characterizes cells as complex information-processing systems.SynBio,on the other hand,toggles further and strives to develop and create its systems from scratch.SynBio is now applied in the development of novel therapeutic drugs for the prevention of human diseases,scale up industrial processes,and accomplish previously unfeasible industrial outcomes.This is made possible through significant breakthroughs in DNA sequencing and synthesis technology,as well as insights gained from synthetic chemistry and systems biology.SynBio technologies have allowed for the introduction of improved and synthetic metabolic functionalities in microorganisms to enable the synthesis of a range of pharmacologically-relevant compounds for pharmaceutical exploration.SynBio applications range from finding new ways to making industrial chemical synthesis processes more sustainable as well as the microbial synthesis of improved therapeutic modalities.Hence,this study underpins several innovations,auspicious potentials,and future directions afforded by SynBio that proposes improved industrial microbial synthesis for pharmaceutical exploration.
基金supported by funding from the National Natural Science Foundation of China (12074435 and 52001335)the Science and Technology Innovation Program of Hunan Province (2021RC4001)the Natural Science Foundation of Yunnan Province (202201AT070259)。
文摘Developing highly efficient and stable platinum-based electrocatalyst for oxygen reduction reaction(ORR) is critical to expediting commercialization of fuel cells.Herein,several PtCu alloy nanocatalysts supported on N,P co-doped carbon(PtCu/NPC) were prepared by microbial-sorption and carbonization-reduction.Among them,PtCu/NPC-700 ℃ exhibits excellent catalytic performance for ORR with a mass activity of 0.895 A mg_(pt)^(-1)(@0.9 V) which is 8.29 folds of commercial Pt/C.Additionally,the ECSA and MA of PtCu/NPC-700℃ only decrease by 14.2% and 18.7% respectively,while Pt/C decreases by 35.2% and 52.8% after 10,000 cycles of ADT test.Moreover,the PtCu/NPC-700℃ catalyst emanates a maximum power density of 715 mW cm^(-2) and only 11.1% loss of maximum power density after 10,000 ADTs in single-cell test,indicating PtCu/NPC-700℃ also manifests higher activity and durability in actual single-cell operation than Pt/C.This research provides an easy and novel strategy for developing highly active and durable Pt-based alloy catalyst.
基金supported by National Key Research and Development Program of China(No.2020YFC1808204-01)Nanchang“Double Hundred Plan”Project(Innovative Talents-Talent Introduction)+1 种基金the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2021TS11)Heilongjiang Provincial Key Laboratory of Environmental Biotechnology and Heilongjiang Touyan Innovation Team Program。
文摘Microbial fabrication of metal nanoparticles(MNPs)has received significant attention due to the advantages of low toxicity,energy efficiency and ecological safety.Diverse groups of MNPs can be synthesized intracellularly or extracellularly by various wild-type microorganisms,including bacteria,fungi,algae and viruses.Synthetic biology approaches,represented by genetic engineering,have been applied to overcome the shortcomings in productivity,stability,and controllability of biosynthetic MNPs.Scanning electron microscope(SEM),transmission electron microscope(TEM)and other characterization techniques assist in deciphering their unique properties.In addition,biosynthetic MNPs have been widely explored for the utilization in environmental remediation and contaminant detection.And machine learning contains a great potential for designing targeted MNPs and predicting their toxicity.This review provides a comprehensive overview of the research progress in the microbial synthesis of MNPs.An outlook on the current challenges and future prospects in the biologically controllable synthesis and engineering environmental applications of MNPs is also provided in this review.
文摘Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles.The experimental conditions of gold and silver nanoparticles production by the cells of studied strains in aqueous chloroauric acid(HAuCIq)and in silver nitrate(AgNO3)solutions,respectively,were determined.Concentration and time-dependences of nanoparticle formation were investigated.The complex of optical and analytical methods was used for testing the gold and silver nanoparticles in the bacterial biomass.The TEM(Transmission Electron Microscopy)and XRD(X-ray Diffraction)data in all cases demonstrated the presence of crystals with fcc(face centered cubic)structure.The results obtained show that the Actinomycetes are capable of producing gold and silver nanoparticles of spherical shape extracellularly when exposed to suitable compounds.The particle size distribution shows that the sizes of nanoparticles are in the range of 5 nm to 80 nm.The biomass obtained may be used for industrial as well as medical and pharmaceutical purposes.
文摘Terpenoids,known for their structural and functional diversity,are highly valued,especially in food,cosmetics,and cleaning products.Microbial biosynthesis has emerged as a sustainable and environmentally friendly approach for the production of terpenoids.However,the natural enzymes involved in the synthesis of terpenoids have problems such as low activity,poor specificity,and insufficient stability,which limit the biosynthesis efficiency.Enzyme engineering plays a pivotal role in the microbial synthesis of terpenoids.By modifying the structures and functions of key enzymes,researchers have significantly improved the catalytic activity,specificity,and stability of enzymes related to terpenoid synthesis,providing strong support for the sustainable production of terpenoids.This article reviews the strategies for the modification of key enzymes in microbial synthesis of terpenoids,including improving enzyme activity and stability,changing specificity,and promoting mass transfer through multi-enzyme collaboration.Additionally,this article looks forward to the challenges and development directions of enzyme engineering in the microbial synthesis of terpenoids.
基金supported by National Key Research and Development Program of China under grant 2021YFC2102700the Basic Research Program of Jiangsu and supported by the Jiangsu Basic Research Center for Synthetic Biology under grant BK20233003+2 种基金National Natural Science Foundation of China under grant 22108122 and 32270082Natural Science Founda〓〓tion of Jiangsu Province under grant BK20202002 and BK20200692the Fundamental Research Funds for the Central Universities under grant JUSRP124020 and Jiangnan University Undergraduate Education and Teaching Reform Research Project under grant No.JG2302038.
文摘Cytochalasans are a class of hybrid polyketide-peptide natural products with diverse activities,including anti-tumor,anti-fungal,anti-parasitic,and anti-HIV properties,demonstrating significant application potential and broad market prospects.With the development of microbial metabolic engineering and synthetic biology,microbial synthesis of cytochalasans has emerged as a cost-effective and efficient alternative to traditional extraction and chemical synthesis methods,facilitating green and sustainable production.To better understand and promote the efficient heterologous biosynthesis of cytocha lasans,this review systematically summarizes and discusses the research progress on the biosynthesis of cytochalasans.Firstly,an overview of the classification,application and biological activity of cytochalasans is provided.Subsequently,we systematically review the relevant gene clusters,enzymes,and biosynthetic pathways involved in the biosynthesis of cytochalasans.Additionally,the latest progress in the design of microbial cell factories for producing cytochalasans and the strategies to enhance their performance are summarized and discussed.Finally,the current challenges in developing efficient cell factories for producing cytochalasans with renewable biomass as a substrate and the corresponding strategies are proposed,aiming to achieve higher-efficiency green biomanufacturing of cytochalasans.
文摘Both enantiomers of fluoxetine were synthesized in five steps from ethyl benzoylacetate (1)using microbial-chemical approach with overall yields of 59% and 62% respectively.(S)-Enan- tiomer can be obtained in >99% e.e.by resting cell of baker's yeast and the R form was produced in 81 % e.e.by immobilized Geotrichum sp.G 38.
基金supported by the National Key Research and Development Program(2019YFA0905703)the National Natural Science Foundation of China(31970065,U1902214)+1 种基金the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIPKJGG-002)the Key Research and Development Plan of Guangdong Province(2022B1111070005).
文摘Verbascoside,which was first discovered in 1963,is a well-known phenylethanoid glycoside(PhG)that exhibits antioxidant,anti-inflammatory,antimicrobial,and neuroprotective activities and contributes to the therapeutic effects of many medicinal plants.However,the biosynthetic pathway of verbascoside remains to be fully elucidated.Here,we report the identification of two missing enzymes in the verbascoside biosynthesis pathway by transcriptome mining and in vitro enzymatic assays.Specifically,a BAHD acyltransferase(hydroxycinnamoyl-CoA:salidroside hydroxycinnamoyltransferase[SHCT])was shown to catalyze the regioselective acylation of salidroside to form osmanthuside A,and a CYP98 hydroxylase(osmanthuside B 3,30-hydroxylase[OBH])was shown to catalyze meta-hydroxylations of the p-coumaroyl and tyrosol moieties of osmanthuside B to complete the biosynthesis of verbascoside.Because SHCTs and OBHs are found in many Lamiales species that produce verbascoside,this pathway may be general.The findings from the study provide novel insights into the formation of caffeoyl and hydroxytyrosol moieties in natural product biosynthetic pathways.In addition,with the newly acquired enzymes,we achieved heterologous production of osmanthuside B,verbascoside,and ligupurpuroside B in Escherichia coli;this work lays a foundation for sustainable production of verbascoside and other PhGs in micro-organisms.
基金the National Natural Science Foundation of China(21533012,21661132006)。
文摘Microbial synthesis utilizes sustainable resources to produce valuable chemicals,as a potential alternative to petroleum-based chemical industry.Although metabolic engineering is an efficient method to enhance the biosynthesis efficacy of microorganisms,it requires complicated biological procedures.Herein,we report a facile intracellular catalysis system for augmenting the production of bio-based material in microorganism.Covalent linking of oligo(p-phenylenevinylene)(OPV)and cyclopentadienyl rhodium(Ⅲ)bipyridine offers intracellular metal catalyst(OPV-Rh).The OPV-Rh complex displayed certain resistance to toxic biomolecules,which guaranteed its catalytic activity in complicated biological systems.With uptake by Gramnegative bacterium Ralstonia eutropha H16(R.eutropha H16),the OPV-Rh complex promotes the transformation of intracellular NADP+to NADPH,which further enhances the biosynthesis of polyhydroxybutyrate(PHB)by this microorganism.This work demonstrates that synthetic metal catalyst can be employed for regulating microbial biosynthesis intracellularly.
基金supported by the General Project of Beijing Excellent Talents Cultivation Project(2014000020124G064)Beijing Municipal Education Commission(SQKM201311417003)+3 种基金the National Basic Research Program of China(‘‘973’’Program)(2012CB725202)the National Natural Science Foundation of China(21276110)the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe‘‘111’’Project(No.111-2-06)
文摘Polyhydroxyalkanoates （PHAs） are a class of natural biopolyesters accumulated intracellularly by many microorganisms. These polymers have attracted particular attention as green plastic in biomedical and industrial applications due to their good biodegradability and bio- compatibility. Poly（3-hydroxybutyrate-co-3-hydroxyvaler- ate） （PHBV） is one of the most common members of PHAs. However, there is no report comparing the properties of PHBV from different groups of producers, e.g., bacteria and haloarchaea. In this study, two types of PHBV copolymers were synthesized in Halogranum amylolyticum and Ralstonia eutropha, respectively, by feeding different carbon sources. They possessed a similar concentration of 3HV monomers （21 tool%） and were named PHBV-H （produced by H. arnylolyticum） and PHBV-B （produced by R. eutropha） based on their source. Interestingly, they exhibited different behaviors especially in thermal stabil- ity, melting temperature, crystallinity percentage, and mechanical properties. Furthermore, the films of PHBV-Hand PHBV-B possessed different surface properties, such as surface roughness, wettability, and surface free energy. The value of hemolysis on the PHBV-H film was lower in comparison with the PHBV-B film, although both values were within the limit of 5 % permissible for biomaterials. Notably, few inactivated platelets adhered to the surface of the PHBV-H film, whereas numerous activated platelets were seen on film PHBV-B. These results indicated that PHBV-H was a better potential component of blood-contact biomaterials than PHBV-B. Our study clearly revealed that the properties of PHAs are source dependent and haloarchaeal species provide a new opportunity for the production of desired PHAs.
文摘A simple and reproducible biosynthetic method was employed to synthesize iron and silver nanoparticles which resulted in monodispersed nanoparticles of high concentration.The iron oxide nanoparticles has been widely favored because of low cytotoxicity,biodegradable and reactive surface that can be modified with biocompatible coatings.Silver nanoparticles have been a potent antibacterial,antifungal,anti-viral and anti-inflammatory agent.The reaction process was simple,eco-friendly,inexpensive and easy to handle.Green and chemical methods were employed to synthesize iron and silver nanoparticles.A microbial route to synthesize iron and silver nanoparticles by the fungal strain Fusarium oxysporum sp.and Actinomycetes sp.was done simultaneously.Production of nanoparticles using fungi has some advantages over other organisms as it is easy to handle and require simple raw materials.The obtained iron and silver nanoparticles were characterized by UV-vis spectroscopy,Fourier transform infrared spectroscopy(FTIR)and the morphology of prepared nanoparticles was confirmed by Transmission electron microscopy(TEM).TEM images of Iron nanoparticles synthesized by Fusarium oxysporum sp.showed 20-40 nm sized particles.These particles exhibited maximum antibacterial activity against Bacillus,E.coli and Staphylococcus sps.TEM images of biosynthesized silver nanoparticles were of smaller size(10-20 nm).The microbially synthesized silver nanoparticles using Actinomycetes were found to be highly toxic against different human pathogens due to the smaller size and due to the presence of antibiotic components available on them.The mechanism of antimicrobial property of nanoparticle lies with the fact that the extremely small size means a large surface area relative to the volume,which effectively covers the microorganisms and reduce oxygen supply for respiration.It was found that silver nanoparticles synthesized by the microbial route have a greater antibacterial activity.
