Multiple stir bar sorptive extraction combined with gas chromatography-mass spectrometry analysis for a tentative identification of bacterial volatile and/or semi-volatile metabolites
Résumé
We propose a new approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and head space sorptive extraction (HSSE). Stir bars have so far never been used for the extraction of volatile/semi-volatile bacterial compounds. The effectiveness of two stir bars with polydimethylsiloxane (PDMS) or ethylene glycol/silicone (EGS) as sorbent was tested by performing sample extraction directly in gas chromatography (GC) via ls containing bacterial cultures. Several combinations of desorption and extraction were tested atdif-ferent growth times. When the extraction was carried out simultaneously with the EGS stir bar in headspace and the PDMS in the bacterial culture, the number of extracted compounds wassignificantly increased. Using both twisters increased the polarity range of thecompounds found, and extraction at the end of the exponential phase of growth generated the best yields. This method was successfully applied to determine the production of 17 molecules by a strain of Staphylococcus aureus. In conclusion, this study paves the way for a new method for determining the volatile metabolite profile of bacteria, which can provide a promising innovative alternative in the identification of biomarkers.
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