Enhancement of acarbose production by rational genetic engineering and process optimization in Actinoplanes sp. SIPI12-34

Abstract

Background Acarbose, as an alpha-glucosidase inhibitor, is widely used clinically to treat type II diabetes. In its industrial production, Actinoplanes sp. SE50/110 is used as the production strain. Lack of research on its regulatory mechanisms and unexplored gene targets are major obstacles to rational strain design. Here, transcriptome sequencing was applied to uncover more gene targets and rational genetic engineering was performed to increase acarbose production. Results In this study, with the help of transcriptome information, a TetR family regulator (TetR1) was identified and confirmed to have a positive effect on the synthesis of acarbose by promoting the expression of acbB and acbD. Some genes with low expression levels in the acarbose biosynthesis gene cluster were overexpressed and this resulted in a significant increase in acarbose yield. In addition, the regulation of metabolic pathways was performed to retain more glucose-1-phosphate for acarbose synthesis by weakening the glycogen synthesis pathway and strengthening the glycogen degradation pathway. Eventually, with a combination of multiple strategies and optimization of culture conditions, the yield of acarbose reached 8.04 g/L, which is the highest fermentation titer reported. Conclusions In our research, acarbose production was significantly improved through genetic engineering and process optimization, breaking through the production bottleneck of traditional screening and random mutagenesis.