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.

Gender-specific differences between the concentrations of nonvolatile (R)/(S)-3-methyl-3-sulfanylhexan-1-Ol and (R)/(S)-3-hydroxy-3-methyl-hexanoic acid odor precursors in axillary secretions.

The volatile fatty acid, (R)/(S)-3-hydroxy-3-methylhexanoic acid ((R)/(S)-HMHA), and the human specific volatile thiol, (R)/(S)-3-methyl-3-sulfanylhexan-1-ol ((R)/(S)-MSH), were recently identified as major components of human sweat malodor. Their 2 corresponding precursors were subsequently isolated from sterile and odorless axillary secretions. The purpose of this work was to analyze these 2 odor precursors in 49 male and female volunteers over a period of 3 years to elucidate to which extent they are implicated in the gender-specific character of body odor. Surprisingly, the ratio between the acid precursor 1, a glutamine conjugate, and the "sulfur" precursor 2, a cysteinylglycine-S-conjugate, was 3 times higher in men than in women with no correlation with either the sweat volume or the protein concentration. Indeed, women have the potential to liberate significantly more (R)/(S)-MSH, which has a tropical fruit- and onion-like odor than (R)/(S)-HMHA (possibly transformed into (E)/(Z)-3-methyl-2-hexenoic acid) that has a cheesy, rancid odor. Parallel to this work, sensory analysis on sweat incubated with isolated skin bacteria (Staphylococcus epidermidis Ax3, Corynebacterium jeikeium American Type Culture Collection 43217, or Staphylococcus haemolyticus Ax4) confirmed that intrinsic composition of sweat is important for the development of body odors and may be modulated by gender differences in bacterial compositions. Sweat samples having the highest sulfur intensity were also found to be the most intense and the most unpleasant.

Survey of extreme solvent tolerance in gram-positive cocci: membrane fatty acid changes in Staphylococcus haemolyticus grown in toluene.

We exploited the unique ecological niche of oil fly larval guts to isolate a strain of Staphylococcus haemolyticus which may be the most solvent-tolerant gram-positive bacterium yet described. This organism is able to tolerate 100% toluene, benzene, and p-xylene on plate overlays and saturating levels of these solvents in monophasic liquid cultures. A comparison of membrane fatty acids by gas chromatography after growth in liquid media with and without toluene showed that in cells continuously exposed to solvent the proportion of anteiso fatty acids increased from 25.8 to 33.7% while the proportion of 20:0 straight-chain fatty acids decreased from 19.3 to 10.1%. No changes in the membrane phospholipid composition were noted. Thus, S. haemolyticus alters its membrane fluidity via fatty acid composition to become more fluid when it is exposed to solvent. This response is opposite that commonly found in gram-negative bacteria, which change their fatty acids so that the cytoplasmic membrane is less fluid. Extreme solvent tolerance in S. haemolyticus is not accompanied by abnormal resistance to anionic or cationic detergents. Finally, six strains of Staphylococcus aureus and five strains of Staphylococcus epidermidis, which were not obtained by solvent selection, also exhibited exceptional solvent tolerance.