Intrageneric competition of staphylococci reveals discrete evolutionary outcomes Open Access

Abstract

We previously identified the diversity of antimicrobial activity in nasal microbiomes that correlates with presence and absence of Staphylococcus aureus. The major competitor of skin surfaces is Staphylococcus epidermidis that can express diverse antimicrobial activities. Ten-fold less frequently found in skin and nasal microbiomes, Staphylococcus hominis is relatively unstudied. The aims of the research were to develop insights into the factors of S. hominis that contribute to the dynamics of competition with these major skin colonising staphylococci. One prominent inhibitory strain, S. hominis was selected to culture with both S. aureus SH1000 and S. epidermidis with aim to use genome sequencing to reveal loci contributing to competition. S. aureus evolved during the competition of S. epidermidis and inhibitor-producing S. hominis to reveal two discrete phenotypes. Non-pigmented clone expressed less alpha-haemolysin and had a SNP in agr Cencoding the receptor of the Agr quorum-sensing system. More Pigmented clone had a SNP in sig Bencoding the accessory sigma factor required for expression of the staphyloxanthin. Distinctively, competition of S. aureus SH1000 with S. epidermidis revealed evolution of S. aureus that corresponded with a SNP in the lytSgene of the LytSR two-component system controlling murein hydrolase activity and autolysis. Pacbio genome sequencing followed by use of AntiSMASH revealed the S. epidermidis inhibitory strain, which enabled persistence of S. hominis, encoded the lantibiotic gallidermin biosynthesis operon on a 39 kb plasmid. Gallidermin decreased S. aureus survival to competitor S. epidermidis, and an increased ability of S. hominis to maintain its population size during evolution experiments, which supported the dynamic relationship of the three staphylococci. Future studies will unravel explanations for the contributions the identified loci make to multi-species competition.

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/content/journal/acmi/10.1099/acmi.ac2019.po0579
2019-04-08
2024-03-28
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