Abstract
During infection processes, Staphylococcus aureus is able to survive within the host and to invade tissues and cells. For studying the interaction between the pathogenic bacterium and the host cell, the bacterial growth behaviour and its metabolic adaptation to the host cell environment provides first basic information. In the present study, we therefore cultivated S. aureus COL and HG001 in the eukaryotic cell culture medium RPMI 1640 and analyzed the extracellular metabolic uptake and secretion patterns of both commonly used laboratory strains. Extracellular accumulation of D-isoleucine was detected starting during exponential growth of COL and HG001 in RPMI medium. This non-canonical D-amino acid is known to play a regulatory role in adaptation processes. Moreover, individual uptake of glucose, accumulation of acetate, further overflow metabolites, and intermediates of the branched-chain amino acid metabolism constitute unique metabolic footprints. Altogether these time-resolved footprint analyses give first metabolic insights into staphylococcal growth behaviour in a culture medium used for infection related studies.
Highlights
Staphylococcus aureus as an important human pathogen causes severe acute nosocomial and community-acquired infections; it shows increasing resistance to common antibiotics [1,2]
With regard to the infection studies, the RPMI 1640 medium is commonly used for the cultivation of eukaryotic cell lines as e.g. epithelial cell lines and macrophages, which are natural counterparts of S. aureus during infection processes
Considering the strong influence of the culture medium on the bacterial physiology, we investigated the exometabolome of S. aureus during growth in the RPMI 1640 medium
Summary
Staphylococcus aureus as an important human pathogen causes severe acute nosocomial and community-acquired infections; it shows increasing resistance to common antibiotics [1,2]. For the precultivation of the bacteria, the usage of complex media like LB [6,9,10], as well as eukaryotic cell culture media is common [11,12] The latter offers three benefits i) the bacteria are not forced to adapt to drastically changed nutritional supply, ii) time consuming washing steps are needless and iii) the bacterial stress response is being kept to a minimum within the experimental setup. Differences in e.g. staphyloxanthin formation and exoprotein expression have already been observed for COL and HG001 [18,20] This gives reason for the assumption that exometabolome data may highlight even more diversity between these two strains
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