AUTHOR=Moran Josephine C. , Alorabi Jamal A. , Horsburgh Malcolm J. 

TITLE=Comparative Transcriptomics Reveals Discrete Survival Responses of S. aureus and S. epidermidis to Sapienic Acid

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00033

DOI=10.3389/fmicb.2017.00033

ISSN=1664-302X

ABSTRACT=<p>Staphylococcal colonization of human skin is ubiquitous, with particular species more frequent at different body sites. Whereas <italic>Staphylococcus epidermidis</italic> can be isolated from the skin of every individual tested, <italic>Staphylococcus aureus</italic> is isolated from &lt;5% of healthy individuals. The factors that drive staphylococcal speciation and niche selection on skin are incompletely defined. Here we show that <italic>S. aureus</italic> is inhibited to a greater extent than <italic>S. epidermidis</italic> by the sebaceous lipid sapienic acid, supporting a role for this skin antimicrobial in selection of skin staphylococci. We used RNA-Seq and comparative transcriptomics to identify the sapienic acid survival responses of <italic>S. aureus</italic> and <italic>S. epidermidis</italic>. Consistent with the membrane depolarization mode of action of sapienic acid, both species shared a common transcriptional response to counteract disruption of metabolism and transport. The species differed in their regulation of SaeRS and VraRS regulons. While <italic>S. aureus</italic> upregulated urease operon transcription, <italic>S. epidermidis</italic> upregulated arginine deiminase, the oxygen-responsive NreABC nitrogen regulation system and the nitrate and nitrite reduction pathways. The role of <italic>S. aureus</italic> ACME and chromosomal arginine deiminase pathways in sapienic acid resistance was determined through mutational studies. We speculate that ammonia production could contribute to sapienic acid resistance in staphylococci.</p>