Phenotypic characteristics contributing to the enhanced growth of Escherichia coli bloom strains

Buddhie S. Nanayakkara, Claire L. O'Brien, David M. Gordon

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


During bloom events, Escherichia coli cell counts increase to between 10,000 and 100,000 cfu/100 ml of water. The strains responsible for bloom events belong to E. coli phylogenetic groups A and B1, and all have acquired a capsule from Klebsiella. A pan-genome comparison of phylogroup A E. coli revealed that the ferric citrate uptake system (fecIRABCDE) was overrepresented in phylogroup A bloom strains compared with non-bloom E. coli. A series of experiments were carried out to investigate if the capsule together with ferric citrate uptake system could confer a growth rate advantage on E. coli. Capsulated strains had a growth rate advantage regardless of the media composition and the presence/absence of the fec operon, and they had a shorter lag phase compared with capsule-negative strains. The results suggest that the Klebsiella capsule may facilitate nutrient uptake or utilization by a strain. This, together with the protective roles played by the capsule and the shorter lag phase of capsule-positive strains, may explain why it is only capsule-positive strains that produce elevated counts in response to nutrient influx.

Original languageEnglish
Article number31642169
Pages (from-to)817-824
Number of pages8
JournalEnvironmental Microbiology Reports
Issue number6
Publication statusPublished - 1 Dec 2019
Externally publishedYes


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