Selective consumption of acetate without sugar degradation by metabolically engineered Escherichia coli
Lakshmanaswamy, Arun Shivkumar
MetadataShow full item record
The removal of acetate from biomass hydrolysate is essential for improving microbial production of biochemicals. This research focuses on microbial removal of acetate using the concept of substrate selective degradation. Acetate is selectively removed from glucose-xylose mixtures by metabolically engineered Escherichia coli strain KD840 with mutations in phosphotransferase system (PTS) genes of glucose (ptsG, manZ, crr), glucokinase (glk) and xylose (xylA). In batch cultures, KD840 consumed acetate exclusively at first, and no sugars were consumed up to 30 hours after acetate was exhausted. Six Escherichia coli strains were compared for maximum specific growth rate using 5 g/L acetate as the sole carbon source. MC4100 showed the greatest MAX at 0.368 h-1 while MG1655 showed the lowest MAX at 0.244 h-1. Interestingly, MC4100 does not have a functional acs-yjcH-yjcG operon. ALS1126 (MG1655 acs-yjcH-yjcG) attained a MAX of 0.262 h-1, indicating acs-yjcH-yjcG operon does not affect the growth rate of E. coli on acetate.