Construction of non-inducible expression systems for engineering of protoilludene production in Escherichia coli with minimal medium

Escherichia coli is an important workhorse for expression of homologous or heterologous genes, and in some cases, non-inducible expression is more preferable than inducible expression due to high level production of target proteins and economic issue. In this work, 10 promoters from the genes that participate in glycolytic pathway in E. coli were evaluated for using monomeric red fluorescence protein (mRFP) as an expression level indicator protein. The results indicated that promoters of gpm (phosphoglycerate mutase) and gap (glyceraldehyde-3-phosphate dehydrogenase) showed much higher activity than other promoters. Protoilludene is a valuable sesquiterpene that is widely used as precursor for anticancer drug illudin and antimicrobial compound melleolide. E. coli is proved a well-performing host for sesquiterpene production when introducing a heterogeneous mevalonate (MVA) pathway. Exploiting glycolytic promoters in protoilludene producing strain, the protoilludene achieved a 4-fold increase compared with the original control without inducer and this amount of protoilludene was roughly flat with original control with inducer in M9 minimal medium. This approach of producing protoilludene in E. coli with the glycolytic promoters would be applied in industrial production.