Exploration of the Phylogenetic Relationship Between Ten Escherichia Coli Lab Strains

Despite the extensive characterization and use of Escherichia coli in metabolic engineering, the relationship between the various lab strains remains underexplored. Here we compare ten E. coli lab strains: C36 (ATCC# 8677), C (ATCC# 8739), W (ATCC# 9637), B (ATCC # 11303), NCTC 9001 (ATCC# 11775), W3100 (ATCC # 14948), ML308 (ATCC # 15224), B/r (ATCC# 23227), MG1655 and DH10B. E. coli O157:H7 and Salmonella typhimurium LT2 were used as non-lab strain controls. 10 kb of sequence data was obtained from seven non-essential regions: ptsG, yeiG, eutS, talA, xylAB, atpI and mutL. A phylogenetic tree of these strains was generated, showing that strains W and NCTC 9001 are the most distinct from the other eight lab strains. Surprisingly, O157:H7 was more similar to the other nine lab strains than NCTC 9001. This analysis revealed a truncation in TalA of strain B and a lack of TalA activity was evidenced by increased menadione sensitivity. Similar to previous reports, the MutL region is prone to variability, with half of the lab strains containing a frame shift that results in premature truncation of MutL. We also found that, of the ten strains, only strain W contains the gene encoding penicillin acylase. Strains W and B/r contain the stably inherited pRK2 plasmid and the immigration control region is found in strains B, B/r, W3100 and MG1655.