Identification and partial characterisation of an extracellular activator of fatty acid modifying enzyme (FAME) expression in Staphylococcus epidermidis

Fatty acid modifying enzyme (FAME) is an extracellular enzyme that inactivates bactericidal fatty acids by esterifying them to cholesterol. Inactivation of these fatty acids may allow Staphylococcus epidermidis to live for long periods of time on the skin. This study describes the identification and partial characterisation of an extracellular activator of FAME production. Addition of FAME-free concentrated culture filtrate (activator) to S. epidermidis cultures (OD600 = 0.05) caused a 3–5-fold increase in FAME activity. Addition of the activator did not increase the amount of exopolysaccharide produced by S. epidermidis. The mol. wt of this activator was <3000 kDa and it was quite resistant to boiling. Treatment of the activator with proteinase K did not destroy its ability to induce FAME expression. Addition of S. aureus activator to S. epidermidis cultures also increased FAME expression. However, when S. epidermidis activator was added to S. aureus cultures no increase or inhibition in FAME production was observed.