Polyhydroxyalkanoates(PHAs)are diversiform biopolyesters with a similar structure and different side chain groups,synthesized by a variety of microorganism.Due to their excellent biodegradability and biocompatibility,...Polyhydroxyalkanoates(PHAs)are diversiform biopolyesters with a similar structure and different side chain groups,synthesized by a variety of microorganism.Due to their excellent biodegradability and biocompatibility,PHAs have been used for many applications,including medical implants,antibacterial agents and bioengineering.Nano-architecture is an emerging area for the use of PHAs.This review summarizes the current status and challenges of PHAs-based particles on the micro-and nano-scale,including their production,degradation,biological safety,and surface functionalization.We also focus on the applications of PHA particles in drug delivery systems,environment protection,tissue engi-neering,vaccine engineering,food science,biotechnology and cosmetics.Finally,the future development trends of PHAs-based particles are prospected.展开更多
The production of polyhydroxyalkanoates （PHAs） with a high fraction of 3-hydroxyvalerate （3HV） and 3-hydroxy-2-methylvalerate （3H2/MV） from mixed culture enriched by valerate-dominant hydrolysate was evaluated i...The production of polyhydroxyalkanoates （PHAs） with a high fraction of 3-hydroxyvalerate （3HV） and 3-hydroxy-2-methylvalerate （3H2/MV） from mixed culture enriched by valerate-dominant hydrolysate was evaluated in this study. After long-term enrichment, the culture showed strong ability to synthesize 3HV and 3H2MV, even with acetate-dominant substrate. The ultilization of single or mixed iso-/n-valerate by the enriched culture showed that the mixture of iso-valerate and n-valerate was more efficient substrate than any single in tenaas of balancing microbial growth and PHAs synthesis. Besides, through comparing the kinetics and stoichiometry of the tests supplying valerate and propionate, the enriched culture with equivalent valerate and propionate （1 ： 1 molar ratio） exhibited superior PHAs production performances to pure valerate or propionate, attaining more than 70 tool% of 3HVand 3H2MV. The above findings reveal that valerate-dominant hydrolysate is a kind of suitable substrate to enrich PHAs producing culture with great capability to synthesize 3HV and 3H2MV monomers, thus improving product properties than pure poly（3-hydroxybutyrate） （P3HB）; also 3HV and 3H2MV production behaviors can be regulated by the type of odd-carbon VFAs in the substrate.展开更多
Aeromonas hydrophila 4AK4 was grown on mixed substrates of soybean oil and lauric acid for the production of polyhydroxyalkanoate copolymer consisting of 3 hydroxybutyrate (3HB) and 3 hydroxyhexanoate (3HHx). A m...Aeromonas hydrophila 4AK4 was grown on mixed substrates of soybean oil and lauric acid for the production of polyhydroxyalkanoate copolymer consisting of 3 hydroxybutyrate (3HB) and 3 hydroxyhexanoate (3HHx). A maximal poly(3 hydroxybutyrate co 3 hydroxyhexanoate) (PHBHHx) content of 49.13% in dry cells was obtained in a shake flask culture. PHBHHx of 6.26 g/L was produced in a fermentation experiment over 48 h on a sole carbon source containing 100 g/L soybean oil, while 12.40 g/L PHBHHx was produced on a mixed carbon source containing 80 g/L soybean and 20 g/L lauric acid over the same period of time, resulting in a polyhydroxyalkanoate (PHA) productivity of 0.25 g/(L·h). The results show that mixed carbon sources are suitable for industrialized production of PHBHHx from A. hydrophila 4AK4, as the mixed carbon sources also overcome the foaming problem that occurs when lauric acid is employed as a sole carbon source in PHBHHx production. 展开更多
Bacterial strains isolated from an oil field at Dagang in Tianjin were found to produce novel polyesters termed polyhydroxyalkanoates (PHAs). Monomers with medium side chain length in the polymers produced by two bact...Bacterial strains isolated from an oil field at Dagang in Tianjin were found to produce novel polyesters termed polyhydroxyalkanoates (PHAs). Monomers with medium side chain length in the polymers produced by two bacterial strains No 0806 and No 1317 grown on glucose were observed using GC(gas chromatography), IR (infrared spectroscopy), and GC MS (gas chromatography mass spectroscopy) analysis. The structures of the PHAs reported in this study are different from the common polyhydroxybutyrate (PHB) often stored by bacteria. 展开更多
Polyhydroxyalkanoates（PHAs）were synthesized in activated sludge using three types of carbon sources（sodium acetate,sodium propionate and sodium butyrate）,and their characterization were studied.It was shown that t...Polyhydroxyalkanoates（PHAs）were synthesized in activated sludge using three types of carbon sources（sodium acetate,sodium propionate and sodium butyrate）,and their characterization were studied.It was shown that the content of PHA synthesized by microorganisms in activated sludge were different.The biggest synthetic amount up to 36.7% of VSS was obtained when sodium acetate was used as carbon source.The polymer yield was lower when using sodium propionate as the carbon source than when using others,with25.1% of VSS,while resulted in an increase of hydroxyvalerate（HV）units produced.The structure and thermal properties of extracted biopolymers were analyzed by scanning electron microscope（SEM）,Fourier transform infrared spectroscopy（FTIR）and themogravimetry（TG）.展开更多
基金supported by Grants from Key Science and Technology Plan Projects in Zigong (grant No.2022ZCNKY07)National Natural Science Foundation of China (grant No.31900950)Jiangxi Provincial Natural Science Foundation (grant No.20212BAB214048).
文摘Polyhydroxyalkanoates(PHAs)are diversiform biopolyesters with a similar structure and different side chain groups,synthesized by a variety of microorganism.Due to their excellent biodegradability and biocompatibility,PHAs have been used for many applications,including medical implants,antibacterial agents and bioengineering.Nano-architecture is an emerging area for the use of PHAs.This review summarizes the current status and challenges of PHAs-based particles on the micro-and nano-scale,including their production,degradation,biological safety,and surface functionalization.We also focus on the applications of PHA particles in drug delivery systems,environment protection,tissue engi-neering,vaccine engineering,food science,biotechnology and cosmetics.Finally,the future development trends of PHAs-based particles are prospected.
文摘The production of polyhydroxyalkanoates （PHAs） with a high fraction of 3-hydroxyvalerate （3HV） and 3-hydroxy-2-methylvalerate （3H2/MV） from mixed culture enriched by valerate-dominant hydrolysate was evaluated in this study. After long-term enrichment, the culture showed strong ability to synthesize 3HV and 3H2MV, even with acetate-dominant substrate. The ultilization of single or mixed iso-/n-valerate by the enriched culture showed that the mixture of iso-valerate and n-valerate was more efficient substrate than any single in tenaas of balancing microbial growth and PHAs synthesis. Besides, through comparing the kinetics and stoichiometry of the tests supplying valerate and propionate, the enriched culture with equivalent valerate and propionate （1 ： 1 molar ratio） exhibited superior PHAs production performances to pure valerate or propionate, attaining more than 70 tool% of 3HVand 3H2MV. The above findings reveal that valerate-dominant hydrolysate is a kind of suitable substrate to enrich PHAs producing culture with great capability to synthesize 3HV and 3H2MV monomers, thus improving product properties than pure poly（3-hydroxybutyrate） （P3HB）; also 3HV and 3H2MV production behaviors can be regulated by the type of odd-carbon VFAs in the substrate.
基金Supported by"985"Foundation of Tsinghua University
文摘Aeromonas hydrophila 4AK4 was grown on mixed substrates of soybean oil and lauric acid for the production of polyhydroxyalkanoate copolymer consisting of 3 hydroxybutyrate (3HB) and 3 hydroxyhexanoate (3HHx). A maximal poly(3 hydroxybutyrate co 3 hydroxyhexanoate) (PHBHHx) content of 49.13% in dry cells was obtained in a shake flask culture. PHBHHx of 6.26 g/L was produced in a fermentation experiment over 48 h on a sole carbon source containing 100 g/L soybean oil, while 12.40 g/L PHBHHx was produced on a mixed carbon source containing 80 g/L soybean and 20 g/L lauric acid over the same period of time, resulting in a polyhydroxyalkanoate (PHA) productivity of 0.25 g/(L·h). The results show that mixed carbon sources are suitable for industrialized production of PHBHHx from A. hydrophila 4AK4, as the mixed carbon sources also overcome the foaming problem that occurs when lauric acid is employed as a sole carbon source in PHBHHx production.
文摘Bacterial strains isolated from an oil field at Dagang in Tianjin were found to produce novel polyesters termed polyhydroxyalkanoates (PHAs). Monomers with medium side chain length in the polymers produced by two bacterial strains No 0806 and No 1317 grown on glucose were observed using GC(gas chromatography), IR (infrared spectroscopy), and GC MS (gas chromatography mass spectroscopy) analysis. The structures of the PHAs reported in this study are different from the common polyhydroxybutyrate (PHB) often stored by bacteria.
基金Supported by the National Science&Technology Pillar Program During the 12th Five-Year Plan Period(2014BAC28B01)Beijing Natural Science Foundation(8112012)
文摘Polyhydroxyalkanoates（PHAs）were synthesized in activated sludge using three types of carbon sources（sodium acetate,sodium propionate and sodium butyrate）,and their characterization were studied.It was shown that the content of PHA synthesized by microorganisms in activated sludge were different.The biggest synthetic amount up to 36.7% of VSS was obtained when sodium acetate was used as carbon source.The polymer yield was lower when using sodium propionate as the carbon source than when using others,with25.1% of VSS,while resulted in an increase of hydroxyvalerate（HV）units produced.The structure and thermal properties of extracted biopolymers were analyzed by scanning electron microscope（SEM）,Fourier transform infrared spectroscopy（FTIR）and themogravimetry（TG）.
