Paper Title
Proteomic and Metabolomicchanges of Staphylococcus Aureus Following Exposure to Combination of Stresses that Present in Human Wound Site

Abstract
Staphylococcus aureus is an importantpathogen that is responsible for a high number of acute and chronic diseases. The ability of this bacterium to induce high numbers of infections is due to its extraordinary capacity to rapidly adapt to changes in environmental conditions. This study was aimed to explore the metabolic and proteomicalterations under various environmental conditions to mimic those on the skin or in a wound site: pH6-8, temperature 35-39 °C, and 0-5% NaCl added. Experiments were designed to examine growth under 10 different combinations with variable factors for pH, temperature and osmotic stress. Cultures grown under optimal conditions at 37°C, pH7, and no added NaCl were designated the reference control samples and those grown with an additional 2.5% NaCl represented the centroid samples with mid-point values of all varied parameters. The cultures were grown to the mid-exponential phase of growth when they were harvested and extracted to examine the amino acid and ribosomal protein responses. The extracted amino acids were analyzed using GC-FID and the proteomics were analyzed by SDS-PAGE and LC-MS/MS.It was found that each set of environmental conditions elicited significant responses in proteomic and metabolomic (P< 0.05). These responses generated unique amino acid and proteins profiles assessed by discriminant function (DF) and principal component analysis (PCA). Significant responses in metabolic and proteomic occurred during growth under conditions of higher osmotic pressure implemented via additional levels of NaCl in the growth medium.The data provided strong evidence that specific alterations in amino acid and protein compositions were associated with the adaptive response to facilitate survival in response to changes in the environmental conditions. Keywords - S. aureus,metabolic homeostasis, phenotype.