Transcriptomic differences between E. coli BL21 and K-12 MG1655 during n-heptanoic acid stress

Biosynthesis of carboxylic acids and fatty acids from renewable biomass is a key issue in biorefinery. However, their productivities are often limited due to various toxic effects of the products on the host organisms. Here, we have investigated the factors that influence tolerance of Escherichia coli to long chain carboxylic acid (e.g., n-heptanoic acid)-induced stress by using transcriptome analysis. The metabolic and genomic responses of E. coli BL21 and MG1655 strains with n-heptanoic acid indicated that acid stress is one of the major stresses, which might be generated by n-heptanoic acid in addition to the presumed solvent-like stress. E. coli cells were grown to the exponential growth phase (OD600 = 0.5), 3 or 10 mM heptanoic acid was treated to BL21(DE3) and K-12 MG1655, respectively. After 3 h incubation, the E. coli cells were harvested for Microarray analysis.