화학공학소재연구정보센터
Applied Microbiology and Biotechnology, Vol.104, No.21, 9309-9325, 2020
Evolution of anEscherichia coliPTS(-)strain: a study of reproducibility and dynamics of an adaptive evolutive process
Adaptive laboratory evolution (ALE) has been used to study and solve pressing questions about evolution, especially for the study of the development of mutations that confer increased fitness during evolutionary processes. In this contribution, we investigated how the evolutionary process conducted with the PTS(-)mutant ofEscherichia coliPB11 in three parallel batch cultures allowed the restoration of rapid growth with glucose as the carbon source. The significant findings showed that genomic sequence analysis of a set of newly evolved mutants isolated from ALE experiments 2-3 developed some essential mutations, which efficiently improved the fast-growing phenotypes throughout different fitness landscapes. RegulatorgalRwas the target of several mutations such as SNPs, partial and total deletions, and insertion of an IS1 element and thus indicated the relevance of a null mutation of this gene in the adaptation of the evolving population of PB11 during the parallel ALE experiments. These mutations resulted in the selection of MglB and GalP as the primary glucose transporters by the evolving population, but further selection of at least a second adaptive mutation was also necessary. We found that mutations in theyfeO,rppH, andrnggenes improved the fitness advantage of evolving PTS(-)mutants and resulted in amplification of leaky activity in Glk for glucose phosphorylation and upregulation of glycolytic and other growth-related genes. Notably, we determined that these mutations appeared and were fixed in the evolving populations between 48 and 72 h of cultivation, which resulted in the selection of fast-growing mutants during one ALE experiments in batch cultures of 80 h duration.