Nonribosomal peptides （NRPs） represent a large family of natural products with great diversities of chemical structures and biological activities. The peptide backbones of NRPs are synthesized by nonribosomal peptid...Nonribosomal peptides （NRPs） represent a large family of natural products with great diversities of chemical structures and biological activities. The peptide backbones of NRPs are synthesized by nonribosomal peptide synthetases （NRPSs） that minimally consist of one adenylation （A） domain, one peptidyl carrier protein （PCP） and one condensation （C） domain. In this study, we carded out a PCR screening and identified 21 ＂positive＂ strains from 100 actinomycete strains with the degenerate primers designed from the conserved sequences of A domains of NRPSs. One of the 21 ＂positive＂ strains, Streptomyces sp. HMU0027, was selected for large-scale fermentation （9 L） based on HPLC analysis, and subsequent isolation and structural elucidation afforded seven NRPS-synthesized thiazostatin siderophore analogues （1-7）. Compound 1 was a new compound containing an unusual linkage between a phenolate siderophore and a sugar moiety. These results laid the foundation for further biosynthetic research of these thiazostatin analogues and highlighted the power of genome mining technologies based on biosynthetic knowledge in NRP discovery.展开更多
A novel phenanthrene (PHE)-degrading strain named as Sphingomonas sp.GF2B was isolated and identified from a farmland soil.Effects of a synthetic surfactant (Tween-80) and a rhamnolipid biosurfactant on PHE degradatio...A novel phenanthrene (PHE)-degrading strain named as Sphingomonas sp.GF2B was isolated and identified from a farmland soil.Effects of a synthetic surfactant (Tween-80) and a rhamnolipid biosurfactant on PHE degradation by Sphin- gomonas sp.GF2B were investigated at different concentrations of the surfactants.The results showed that Sphingomonas sp.GF2B was able to mineralize up to 83.6% of PHE within 10 days without addition of surfactants.The addition of Tween-80 to the reaction medium inhibited greatly PHE biodegradation,with only 33.5% of PHE degraded.However,the biosurfactant facilitated PHE biodegradation,with up to 99.5% of PHE degraded.The preferential utilization of PHE as a carbon source and the enhanced solubility of PHE by the biosurfactant were likely responsible for the higher biodegra- dation efficiency of PHE in the presence of the biosurfactant.Therefore,it could be concluded that the application of the biosurfactant to PHE-contaminated soils was perhaps a feasible way to facilitate the PHE biodegradation.展开更多
1,3-Propanediol （PDO） is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high produc...1,3-Propanediol （PDO） is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high production of PDO by fermentation of glycerol. The PDO productivities of the isolated strains were tested, and the strain with highest PDO productivity was characterized using the API20E and 16-s rRNA sequence analysis. The physiological and phylogenetic analysis indicated that the strain was closed related to K. pneumoniae species and was named as K. pneumoniae HSL4. The structure of the dha cluster which was responsible for the biosynthesis of PDO was analyzed. It is observed that K. pneumoniae HSL4 was tolerant to salt and partly tolerant to acetate and lactate, which will favor industrial applications. Fed-batch fermentation experiments revealed K. pneumoniae HSL4 exhibited an excellent ability to produce PDO with high concentration （80.08 g L^-1）, productivity （2.22 g L^-1h^-1） and conversion （0.435 g g^-1 or 0.53 mol mol^-1）. The metabolic flux profile illuminated that glycerol was consumed rapidly and PDO was accumulated quickly to a high level during the exponential growth phase. This study provided important information for further fermentation and metabolic engineering of PDO production by K. pneumoniae HSL4.展开更多
基金The National Natural Science Foundation of China(Grant No.81573326,Grant No.81673332)
文摘Nonribosomal peptides （NRPs） represent a large family of natural products with great diversities of chemical structures and biological activities. The peptide backbones of NRPs are synthesized by nonribosomal peptide synthetases （NRPSs） that minimally consist of one adenylation （A） domain, one peptidyl carrier protein （PCP） and one condensation （C） domain. In this study, we carded out a PCR screening and identified 21 ＂positive＂ strains from 100 actinomycete strains with the degenerate primers designed from the conserved sequences of A domains of NRPSs. One of the 21 ＂positive＂ strains, Streptomyces sp. HMU0027, was selected for large-scale fermentation （9 L） based on HPLC analysis, and subsequent isolation and structural elucidation afforded seven NRPS-synthesized thiazostatin siderophore analogues （1-7）. Compound 1 was a new compound containing an unusual linkage between a phenolate siderophore and a sugar moiety. These results laid the foundation for further biosynthetic research of these thiazostatin analogues and highlighted the power of genome mining technologies based on biosynthetic knowledge in NRP discovery.
基金Supported by the National Natural Science Foundation of China (No. 20377024)the National High Technology Research and Development Program (863 Program) of China (Nos. 2007AA061101 and 2009AA063103)
文摘A novel phenanthrene (PHE)-degrading strain named as Sphingomonas sp.GF2B was isolated and identified from a farmland soil.Effects of a synthetic surfactant (Tween-80) and a rhamnolipid biosurfactant on PHE degradation by Sphin- gomonas sp.GF2B were investigated at different concentrations of the surfactants.The results showed that Sphingomonas sp.GF2B was able to mineralize up to 83.6% of PHE within 10 days without addition of surfactants.The addition of Tween-80 to the reaction medium inhibited greatly PHE biodegradation,with only 33.5% of PHE degraded.However,the biosurfactant facilitated PHE biodegradation,with up to 99.5% of PHE degraded.The preferential utilization of PHE as a carbon source and the enhanced solubility of PHE by the biosurfactant were likely responsible for the higher biodegra- dation efficiency of PHE in the presence of the biosurfactant.Therefore,it could be concluded that the application of the biosurfactant to PHE-contaminated soils was perhaps a feasible way to facilitate the PHE biodegradation.
基金supported by the Scientific Research Project of the Marine Public Welfare Industry of China (201205020-4)Administration of Ocean and Fisheries of Guangdong Province (GD2012-D01-002)
文摘1,3-Propanediol （PDO） is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high production of PDO by fermentation of glycerol. The PDO productivities of the isolated strains were tested, and the strain with highest PDO productivity was characterized using the API20E and 16-s rRNA sequence analysis. The physiological and phylogenetic analysis indicated that the strain was closed related to K. pneumoniae species and was named as K. pneumoniae HSL4. The structure of the dha cluster which was responsible for the biosynthesis of PDO was analyzed. It is observed that K. pneumoniae HSL4 was tolerant to salt and partly tolerant to acetate and lactate, which will favor industrial applications. Fed-batch fermentation experiments revealed K. pneumoniae HSL4 exhibited an excellent ability to produce PDO with high concentration （80.08 g L^-1）, productivity （2.22 g L^-1h^-1） and conversion （0.435 g g^-1 or 0.53 mol mol^-1）. The metabolic flux profile illuminated that glycerol was consumed rapidly and PDO was accumulated quickly to a high level during the exponential growth phase. This study provided important information for further fermentation and metabolic engineering of PDO production by K. pneumoniae HSL4.
