Transcriptome Analysis Of Streptomyces Cinnamonensis And Regulation On Monensin Biosynthesis

Monensin is the first polyether ionophore antibiotic used in the treatment of coccidiosis in poultry animals,and produced by Streptomyces cinnamonensis.The synthesis of monensin requires the supply of acyl-Co A precursors and is therefore directly affected by multiple primary metabolic pathways.Moreover,the synthesis of monensin is regulated by many transcriptional regulators,inclusive of pathway-specific regulators and global regulators.At present,what has been identified is three pathway-specific regulatory factors,which have a complex regulation mode.However,it also possesses a large number of global transcription factors in S.cinnamonensis,but less researches focus on it.The result of analysis the transcriptomics over primary and secondary metabolic in S.cinnamonensis showed that the transcription levels of many genes have significantly changed.Then,by analyzing the pathways involved in the synthesis of monensin precursors,such as β oxidation of fatty acids,degradation of branched-chain amino acids and central carbon metabolism,a series of target genes,including ccr,pccB,acs,facl,acad,bkd A1,bkdB2,zwf,and pckA,etc.have been predicted.The transcriptional level changes of regulator in S.cinnamonensis were also analyzed,then through gene overexpression and knockout,it was determined that two regulator positively regulate the synthesis of monensin.The monensin titers of overexpression strains STOE02 and STOE05 were increased by 21.8 % and 37.3%compared with the original strain,respectively.The production of their deletion strains is reduced.The RT-PCR experiments showed that STOE02 increased the transcription level of two transcription units of monensin cluster,which increase the production of monensin by upregulating the transcription level of the monT,monRI,monRII and monAX.The MTF05 increased the transcription level of four,which increase the production of monensin by increasing the transcription level of monCII、monE、monT、monRII、monAIV、monAV、monAVI、monH and monD.Eventually,a combined overexpression strain of two positively regulators was constructed,and its monensin production reached 1.14 g/L,which was 50.9% higher than the original strain.