The effects of nitrogen sources on streptolydigin production and distribution of secondary metabolites were investigated for flask cultured S.lydicus AS 4.2501.When peptone,asparamide,and glutamic acid were ex- amined...The effects of nitrogen sources on streptolydigin production and distribution of secondary metabolites were investigated for flask cultured S.lydicus AS 4.2501.When peptone,asparamide,and glutamic acid were ex- amined as the nitrogen source,respectively,liquid chromatography-mass spectrometry(LC-MS)and photodiode array(PDA)analyses revealed the formation of two analogues of streptolydigin in the fermentation broth.When soybean meal was used as the source of nitrogen,three analogues of streptolydigin were detected.The use of am- monium sulfate as a source of nitrogen resulted in a lower pH value of the fermentation system,thus inhibiting streptolydigin biosynthesis and changing the metabolic profiling.Among the nitrogen sources that were made use of,glutamic acid was most favorable to the formation of streptolydigin.Simultaneously,this study also showed that the changing nitrogen sources resulted in altering the production and relative ratios of streptolydigin and its analogues.展开更多
To achieve higher antibiotic streptolydigin productivity through metabolic regulation, propionate was fed during the fermentation of Streptomyces lydicus AS 4.2501. The effects of propionate feeding on streptolydigin ...To achieve higher antibiotic streptolydigin productivity through metabolic regulation, propionate was fed during the fermentation of Streptomyces lydicus AS 4.2501. The effects of propionate feeding on streptolydigin production and intracellular fluxes were investigated. The highest streptolydigin production yield of 95.10mg·L-1 was obtained when 2mmol·L-1 of sodium propionate was added at 60h of cultivation into shake-flask culture. This yield is 23.06% higher when compared to that of a batch culture without propionate supplementation. It was also found that when propionate was added, much more organic acids were excreted. Metabolic flux analysis was per-formed and it demonstrated that the carbon fluxes of the pentose phosphate pathway and the anaplerotic reaction were significantly increased after propionate feeding. The carbon flux from pyruvate to acetyl-CoA was determined to be 24.7, which was 12.27% higher than that in the batch culture. This study indicated that the glu-cose-6-phosphate and pyruvate nodes were potential bottlenecks for increasing streptolydigin productivity. Potential targets and strategies that could be manipulated through genetic and process engineering to increase the production of streptolydigin were also suggested.展开更多
The actinomycete Streptomyces lydicus A_(01) promotes tomato seedling growth; however, the underlying mechanism is unclear. In this study, we investigated whether changes in soil microbial diversity, following Strepto...The actinomycete Streptomyces lydicus A_(01) promotes tomato seedling growth; however, the underlying mechanism is unclear. In this study, we investigated whether changes in soil microbial diversity, following Streptomyces lydicus A_(01) treatment, were responsible for the increased tomato seedling growth. Eukaryotic 18 S ribosomal DNA(rDNA) sequencing showed that S. lydicus A_(01)-treated and untreated soil shared 193 operational taxonomic units(OTUs), whereas bacterial 16 S rDNA sequencing identified 1,219 shared OTUs between the treated and untreated soil. Of the 42 dominant eukaryotic OTUs, eight were significantly increased and six were significantly decreased after A_(01) treatment. Of the 25 dominant bacterial OTUs, 12 were significantly increased and eight were significantly decreased after A_(01) treatment.Most of the eukaryotes and bacteria that increased in abundance exhibited growth promoting characteristics,which were mainly predicted to be associated with mineralization of nitrogen and phosphorus, phosphate solubilization, nutrient accumulation, and secretion of auxin, whereas some were related to plant protection,such as the degradation of toxic and hazardous substances. Soil composition tests showed that S. lydicus A_(01) treatment enhanced the utilization of nitrogen, phosphorus, and potassium in tomato seedlings. Thus, microbial fertilizers based on S. lydicus A_(01) may improve plant growth, without the detriment effects of chemical fertilizers.展开更多
基金Supported by the Natjonal Natural Science Foundation of China （No.20425620） and the Program for Changjiang Scholars and Innovative Research Team in University from the Ministry of Education of China.
文摘The effects of nitrogen sources on streptolydigin production and distribution of secondary metabolites were investigated for flask cultured S.lydicus AS 4.2501.When peptone,asparamide,and glutamic acid were ex- amined as the nitrogen source,respectively,liquid chromatography-mass spectrometry(LC-MS)and photodiode array(PDA)analyses revealed the formation of two analogues of streptolydigin in the fermentation broth.When soybean meal was used as the source of nitrogen,three analogues of streptolydigin were detected.The use of am- monium sulfate as a source of nitrogen resulted in a lower pH value of the fermentation system,thus inhibiting streptolydigin biosynthesis and changing the metabolic profiling.Among the nitrogen sources that were made use of,glutamic acid was most favorable to the formation of streptolydigin.Simultaneously,this study also showed that the changing nitrogen sources resulted in altering the production and relative ratios of streptolydigin and its analogues.
基金Supported by the National Natural Science Foundation of China (No.20425620)the Program for Changjiang Scholars andInnovative Research Team in University from the Ministry of Education of China.
文摘To achieve higher antibiotic streptolydigin productivity through metabolic regulation, propionate was fed during the fermentation of Streptomyces lydicus AS 4.2501. The effects of propionate feeding on streptolydigin production and intracellular fluxes were investigated. The highest streptolydigin production yield of 95.10mg·L-1 was obtained when 2mmol·L-1 of sodium propionate was added at 60h of cultivation into shake-flask culture. This yield is 23.06% higher when compared to that of a batch culture without propionate supplementation. It was also found that when propionate was added, much more organic acids were excreted. Metabolic flux analysis was per-formed and it demonstrated that the carbon fluxes of the pentose phosphate pathway and the anaplerotic reaction were significantly increased after propionate feeding. The carbon flux from pyruvate to acetyl-CoA was determined to be 24.7, which was 12.27% higher than that in the batch culture. This study indicated that the glu-cose-6-phosphate and pyruvate nodes were potential bottlenecks for increasing streptolydigin productivity. Potential targets and strategies that could be manipulated through genetic and process engineering to increase the production of streptolydigin were also suggested.
基金supported by the National Key Research and Development Program of China (Synergism of Live Bio-pesticides and Related Mechanism of Ecological Regulation on Pest, No.2017YFD0200403 The new highly efficient bio-fungicide, No.2017YFD0201108)+4 种基金Beijing Municipal Science and Technology Plan Projects (No.D151100003915002, D151100003915003)National Natural Science Foundation of China (No.31270155)Beijing Natural Science Foundation (No.6152007)Special Project for Innovation Ability Construction of BAAFS (No.KJCX20170415)the National Special Project of Basic Work Project for Science and Technology (No.2014FY120900)
文摘The actinomycete Streptomyces lydicus A_(01) promotes tomato seedling growth; however, the underlying mechanism is unclear. In this study, we investigated whether changes in soil microbial diversity, following Streptomyces lydicus A_(01) treatment, were responsible for the increased tomato seedling growth. Eukaryotic 18 S ribosomal DNA(rDNA) sequencing showed that S. lydicus A_(01)-treated and untreated soil shared 193 operational taxonomic units(OTUs), whereas bacterial 16 S rDNA sequencing identified 1,219 shared OTUs between the treated and untreated soil. Of the 42 dominant eukaryotic OTUs, eight were significantly increased and six were significantly decreased after A_(01) treatment. Of the 25 dominant bacterial OTUs, 12 were significantly increased and eight were significantly decreased after A_(01) treatment.Most of the eukaryotes and bacteria that increased in abundance exhibited growth promoting characteristics,which were mainly predicted to be associated with mineralization of nitrogen and phosphorus, phosphate solubilization, nutrient accumulation, and secretion of auxin, whereas some were related to plant protection,such as the degradation of toxic and hazardous substances. Soil composition tests showed that S. lydicus A_(01) treatment enhanced the utilization of nitrogen, phosphorus, and potassium in tomato seedlings. Thus, microbial fertilizers based on S. lydicus A_(01) may improve plant growth, without the detriment effects of chemical fertilizers.
