PRODUCTION OF SULFITE AND SULFIDE BY LOW-SULFITE AND HIGH-SULFITE FORMING WINE YEASTS

The influence of vitamin and cysteine supplementation on sulfite and sulfide formation, and on ATP sulfurylase activity, by 2 low- and 2 high-sulfite forming wine yeasts [Saccharomyces spp.] is examined using a defined synthetic fermentation substrate. The low-sulfite formers produce more sulfite in media lacking vitamins, whereas the high-sulfite formers produce less. One high-sulfite former has elevated ATP sulfurylase activity, but the other has activity similar to a low-sulfite forming strain. Only traces of sulfide are formed when the high-sulfite formers are grown with sulfate as the S source, but considerable amounts are produced when cysteine is added to the medium. The low-sulfite formers produce H2S in the complete medium, and more is formed when vitamins are omitted.