The level of variation in hydrogen sulfide formation as a function of yeast genetic background was evaluated for 170 strains, comprised of 169 commercial strains and one native isolate, using six different media: BiGGY agar (assess basal levels of sulfite reductase), synthetic grape juice media with differing nitrogen and vitamin content, and Syrah grape juice. Statistical and cluster analysis placed the strains into 15 clusters, ranging from 1 to 43 members. Sulfide production was not well correlated with the nitrogen content of the medium. In general, sulfide formation was highest in the Syrah juice, in both total number of strains producing the compound and in level of production. There was no correlation between colony color on BiGGY agar and level of production of H2S in any of the liquid media. Strains producing high levels of H2S in Syrah also tended to produce H2S in at least one of the synthetic media. Many moderate to low level producers of H2S in Syrah produced trace to undetectable levels of H2S in synthetic media. Thus, synthetic media can be used to identify strains with the potential to produce high levels of H2S during fermentation. However, a low level of sulfide production in synthetic juices does not indicate low level of production in juice, and strain evaluation in actual juices is still necessary.
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