定向进化形态相关基因bolA提高大肠杆菌的耐酸性

In industrial microbial fermentation, acid stress accumulation is a common issue limiting efficiency. By targeting the morphological gene-related transcription factor bolA, four superior mutant strains were obtained through error-prone PCR library screening. One mutant with enhanced promoter activity in the HTH domain showed an 18.87% biomass increase at pH 5.0 with succinic acid, while another mutant at the C-terminal showed a 27.80% biomass increase at pH 5.0 with HCl. Confocal microscopy confirmed mutants promoted cell aggregation and biofilm formation through EPS secretion. Fluorescence analysis revealed significant increases in tyrosine (137.09%-198.50%) and tryptophan (45.87%-59.54%) protein content in the enhanced promoter mutant. EPS analysis showed a 19.30%-24.45% increase in protein content. Transmission electron microscopy indicated mutants tended to shift from rod-shaped to spherical, facilitating cell aggregation. Real-time qPCR showed bolA\'s involvement in upregulating genes related to biofilm formation, flagellar movement, and membrane pore proteins in the mutants.