Evaluation of the transcription of small RNA SgrS and glucose transporter mRNA ptsG in E. coli B and E. coli K cultures under high glucose conditions

Abstract

<italic>Escherichia coli</italic> is commonly used as the production system for recombinant proteins. However, acetate accumulation in fermentation affects cell growth and protein yield. Recent studies have showed that the small RNA SgrS regulates the major glucose transporter mRNA <italic>ptsG</italic> in a post&ndash;transcriptional manner when the metabolic intermediate glucose&ndash;6&ndash;phosphate is accumulated intracellularly in <italic>E. coli</italic> K. Here, comparative analysis of the transcription of SgrS and <italic>ptsG</italic> is performed between <italic>E. coli</italic> B and <italic>E. coli</italic> K cultures in both shake flasks and bioreactor. Both strains expressed SgrS when grown on the non&ndash;metabolizable glucose analog &alpha;&ndash;methyl&ndash;glucoside. However, under high glucose conditions, only <italic>E. coli</italic> B showed significant expression of SgrS. This behavior is unaffected by oxygen supply and pH control. <italic>E. coli</italic> B produced less acetate on glucose than <italic>E. coli</italic> K in the bioreactor settings. This provides evidence of a possible connection between SgrS and acetate production in aerobic fermentation of <italic>E. coli</italic>.