Screening The Chemically Defined Media For Erythromycin Biosynthesis And Their Impacts On The Metabolic Regulation Of Saccharopolyspora Erythraea

Due to the increasing of microbial resistance to antibiotics,increasing studies focus on the third generation antibiotics and the semisynthetic drugs derived form erythromycin which uses erythromycin as raw material.At present,the low erythromycin titer and low active constituent lead to the weak competitiveness in the international market.It is in urgent need for optimal synthetic medium to realize the rational genetic engineering of over-production strain and to figure out the key metabolites in erythromycin synthesis pathway.To solve this problem,the high-throughput screening method was adopted here to screen the synthetic medium.With the optimized synthetic medium,the relationship between erythromycin production and intracellular metabolite pools was also explored.Firstly,based on a high-throughput method,single factor deficiency experiment and the Plackett-Burman method were employed to screen the essential compounds of the medium and optimize their concentrations.A high-producing synthetic medium with erythromycin titer of 1113μg/mL was obtained.Secondly,the productivity of the synthetic medium was confirmed in 5 L fermentor,and based on substrate consumption curve,the nitrogen resource and phosphate resource were optimized again and four constituents of the synthetic medium were deleted.The erythromycin titer was 1380 μg/mL by using this synthetic medium,which was 11.5-fold higher than that in previously reported literature.Finally,the intracellular metabolites concentrations under different recipes of synthetic media were compared.During the erythromycin production phase,PP pathway was more active than the EMP pathway.propionyl-CoA and methylmalonyl-CoA intracellular pools were positively correlated to erythromycin production.