Comparative study on nutrient depletion-induced lipidome adaptations in Staphylococcus haemolyticus and Staphylococcus epidermidis

Staphylococcus species are emerging opportunistic pathogens that cause outbreaks of hospital and community-acquired infections. Some of these bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are difficult to treat due to their resistance to multiple antibiotics. We carried out a comparative study on the lipidome adaptations in response to starvation in the two most common coagulase-negative Staphylococcus species: a S. epidermidis strain sensitive to ampicillin and erythromycin and a S. haemolyticus strain resistant to both. The predominant fatty acid composition in glycerolipids was (17:0–15:0) in both bacteria. During the exponential phase, the two bacterial lipidomes were similar. Both were dominated by diacylglycerol (DAG), phosphatidylglycerol (PG), lysyl-phosphatidylglycerol (Lysyl-PG) and Diglucosyl-diacylglycerol (DGDG). Alanyl-PG was detected in small amounts in both bacterial lipids. N-succinyl-lysyl-PG was detected only in S. haemolyticus, while lysyl-DAG only in S. epidermidis. As the two bacteria entered stationary phase, both lipidomes became essentially nitrogen-free. Both bacteria accumulated large amounts of free fatty acids. Strikingly, the lipidome of S. epidermidis became dominated by cardiolipin (CL), while that of S. haemolyticus was simplified to DGDG and PG. The S. epidermidis strain also produced acyl-phosphatidylglycerol (APG) in the stationary phase.