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Core Genome 9.2.2.1 Metabolism

Enzymes of metabolic pathways are usually encoded within the core genome. S. aureus is capable of growth using a range of sugars as energy source. Consequently, the complete set of genes of the glycolytic and pentose phosphate pathway and the tricarboxylic acid cycle are found in the genome. Interestingly, S. aureus metabolizes lactose and galactose via the D-tagatose-6-phosphate pathway. Thus, all genes encoding enzymes of this pathway are also present in the S. aureus genome, including a phosphotransferase system to transport lactose [14]. On the other hand, no transport systems for arabinose and mannose were found. The ability of S. aureus to metabolize lactose and galactose may be important to its growth in milk; S. aureus is one the leading causes of mastitis in humans and cattle. Importantly, the major difference between S. aureus and S. epidermidis in relation to carbohydrate transport is the absence of three phosphotransferase system (PTS) transporters for mannitol, sorbitol, and pentitol in S. epidermidis [17]. Sta-phylococci have been recognized as well-adapted to living on mucosal surfaces and the skin by dealing with osmotic stress. To counterbalance environmental stress due to high salt conditions, S. aureus possesses seven sodium ion/proton exchangers and S. epidermidis eight. In addition, both organisms encode six trans-

Table9.1 Summarized features of eight staphylococcal genomes.

Staphylococcus aureus Staphylococcus epidermidis

Table9.1 Summarized features of eight staphylococcal genomes.

Staphylococcus aureus Staphylococcus epidermidis

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