Regulation of hydrogen sulfide liberation in wine-producing Saccharomyces cerevisiae strains by assimilable nitrogen

Jiranek, V., Langridge, P. and Henschke, P.A. (1995) Regulation of hydrogen sulfide liberation in wine-producing Saccharomyces cerevisiae strains by assimilable nitrogen. Applied and Environmental Microbiology, 61 (2), 461-467. (doi:10.1128/aem.61.2.461-467.1995).

Abstract

Saccharomyces cerevisiae wine-producing yeast cultures grown under model winemaking conditions could be induced to liberate hydrogen sulfide (H₂S) by starvation for assimilable nitrogen. The amount of H₂S produced was dependent on the yeast strain, the sulfur precursor compound, the culture growth rate, and the activity of the sulfite reductase enzyme (EC 1.8.1.2) immediately before nitrogen depletion. Increased H₂S formation relative to its utilization by metabolism was not a consequence of a de novo synthesis of sulfite reductase. The greatest amount of H₂S was produced when nitrogen became depleted during the exponential phase of growth or during growth on amino acids capable of supporting short doubling times. Both sulfate and sulfite were able to act as substrates for the generation of H₂S in the absence of assimilable nitrogen; however, sulfate reduction was tightly regulated, leading to limited H₂S liberation, whereas sulfite reduction appeared to be uncontrolled. In addition to ammonium, most amino acids were able to suppress the liberation of excess H₂S when added as sole sources of nitrogen, particularly for one of the strains studied. Cysteine was the most notable exception, inducing the liberation of H₂S at levels exceeding that of the nitrogen-depleted control. Threonine and proline also proved to be poor substitutes for ammonium. These data suggest that any compound that can efficiently generate sulfide-binding nitrogenous precursors of organic sulfur compounds will prevent the liberation of excess H₂S.

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Contributors

Author: V. Jiranek

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