An efficient ammonia nitrogen degrading bacterial strain was isolated from a fish and shrimp pond and identified as Bacillus subtilis(Ab03).Firstly,the strain was continuously domesticated in ammonium solution to impr...An efficient ammonia nitrogen degrading bacterial strain was isolated from a fish and shrimp pond and identified as Bacillus subtilis(Ab03).Firstly,the strain was continuously domesticated in ammonium solution to improve its nitrogen removal capacity.The performance of the strain in terms of nitrogen removal efficiency under different culture conditions was then examined.Finally,the nitrogen removal process and related strain mechanisms were analyzed by nitrogen balance.The results showed the strain Ab03 could remove 91.67% of NH_(4)^(+)-N at 300 mg/L under the conditions of glucose as the single carbon source,C/N of 15,pH of 7.5,the temperature of 35℃ and dissolved oxygen of 7-8 mg/L.It was also found that under conditions where ammonia nitrogen was the only nitrogen source,strain Ab03 could also undergo aerobic denitrification for simultaneous conversion,with a final gas conversion rate of 74.81%.展开更多
Prodigiosin is a secondary metabolite mainly produced at 30°C in Serratia marcescens,but it can hardly be synthetized at 37°C or higher.In this study,we provide insight into the metabolic regulation of prodi...Prodigiosin is a secondary metabolite mainly produced at 30°C in Serratia marcescens,but it can hardly be synthetized at 37°C or higher.In this study,we provide insight into the metabolic regulation of prodigiosin synthesis in response to temperature through transcriptome sequencing.The analysis of the function of differentially expressed genes suggested that temperature resulted in significant alteration of the metabolic pathways between 30 and 37°C.Specifically,30°C favored transcriptional expression of the pig gene cluster.At the same time,the carbon flux was redistributed to pathways of pyruvate,proline,serine,especially homoserine,cystathionine,homocysteine,methionine,and s-adenosylmethionine metabolism,all involved in prodigiosin biosynthesis,and was finally increased towards the prodigiosin synthesis pathway in S.marcescens at 30°C.Interestingly,results further confirmed increased transcriptional level of five regulators(LuxS,RpoS,Hfq,EepR,CRP),and decreased content of hexS through qPCR.Finally,successful co-overexpression of mmuM and metK,related to homocysteine,methionine,and s-adenosylmethionine metabolism,in the chromosome of JNB5-1(JNB5-1/MK)resulted in increased prodigiosin titer up to 7.57 g/L in JNB5-1/MK at 30°C,which was 41.2%higher than that in JNB5-1.Our transcriptome analysis provides further insight into the strain’s response to temperature changes at the transcription level,which is of great significance for improving the production of prodigiosin.展开更多
基金supported by the Foundation of Fujian Key Laboratory of Functional Aquafeed and Culture Environment Control(No.FACE20200003)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,Top-notch Academic Programs Project of Jiangsu Higher Education Institutions,1.111 Project(111-2-06)Jiangsu province"Collaborative Innovation Center for Advanced Industrial Fermentation"industry development program.
文摘An efficient ammonia nitrogen degrading bacterial strain was isolated from a fish and shrimp pond and identified as Bacillus subtilis(Ab03).Firstly,the strain was continuously domesticated in ammonium solution to improve its nitrogen removal capacity.The performance of the strain in terms of nitrogen removal efficiency under different culture conditions was then examined.Finally,the nitrogen removal process and related strain mechanisms were analyzed by nitrogen balance.The results showed the strain Ab03 could remove 91.67% of NH_(4)^(+)-N at 300 mg/L under the conditions of glucose as the single carbon source,C/N of 15,pH of 7.5,the temperature of 35℃ and dissolved oxygen of 7-8 mg/L.It was also found that under conditions where ammonia nitrogen was the only nitrogen source,strain Ab03 could also undergo aerobic denitrification for simultaneous conversion,with a final gas conversion rate of 74.81%.
基金This work was supported by the National Key Research and Development Program of China(2018YFA0900300)the National Natural Science Foundation of China(31870066,21778024)+1 种基金National First-Class Discipline Program of Light Industry Technology and Engineering(LITE2018-06)the Program of Introducing Talents of Discipline to Universities(111-2-06).
文摘Prodigiosin is a secondary metabolite mainly produced at 30°C in Serratia marcescens,but it can hardly be synthetized at 37°C or higher.In this study,we provide insight into the metabolic regulation of prodigiosin synthesis in response to temperature through transcriptome sequencing.The analysis of the function of differentially expressed genes suggested that temperature resulted in significant alteration of the metabolic pathways between 30 and 37°C.Specifically,30°C favored transcriptional expression of the pig gene cluster.At the same time,the carbon flux was redistributed to pathways of pyruvate,proline,serine,especially homoserine,cystathionine,homocysteine,methionine,and s-adenosylmethionine metabolism,all involved in prodigiosin biosynthesis,and was finally increased towards the prodigiosin synthesis pathway in S.marcescens at 30°C.Interestingly,results further confirmed increased transcriptional level of five regulators(LuxS,RpoS,Hfq,EepR,CRP),and decreased content of hexS through qPCR.Finally,successful co-overexpression of mmuM and metK,related to homocysteine,methionine,and s-adenosylmethionine metabolism,in the chromosome of JNB5-1(JNB5-1/MK)resulted in increased prodigiosin titer up to 7.57 g/L in JNB5-1/MK at 30°C,which was 41.2%higher than that in JNB5-1.Our transcriptome analysis provides further insight into the strain’s response to temperature changes at the transcription level,which is of great significance for improving the production of prodigiosin.
