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 mu g/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-alpha-deamino-gamma-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. (c) 2005 Elsevier Ltd. All rights reserved.