Identification of volatile sulfur compounds produced by Shigella sonnei using gas chromatography–olfactometry

This study investigates volatile sulfur compound production by Shigella sonnei cultured on tryptic soy agar (TSA) and TSA supplemented with 80 μg/ml of the antibiotic rifampicin (TSA-R). Headspace volatiles were trapped and concentrated using solid phase microextraction and identified by gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectroscopy (GC–MS). Results identified two aroma active compounds: methanethiol (MT) and dimethyl sulfide (DMS). Potential pathways of MT and DMS formation were identified as the breakdown of l-methionine by l-methionine-α-deamino-γ-mercaptomethane-lyase (METase) and METase-mediated metabolism of methylated l-methionine, respectively. DMSO, used in TSA-R preparation, may have contributed to an increase in malodor production due to the action of DMSO reductase.