Identification of Genes Affecting Hydrogen Sulfide Formation inSaccharomyces cerevisiae

Abstract

A screen of the Saccharomyces cerevisiae deletion strain set was performed to identify genes affecting hydrogen sulfide (H 2 S) production. Mutants were screened using two assays: colony color on BiGGY agar, which detects the basal level of sulfite reductase activity, and production of H 2 S in a synthetic juice medium using lead acetate detection of free sulfide in the headspace. A total of 88 mutants produced darker colony colors than the parental strain, and 4 produced colonies significantly lighter in color. There was no correlation between the appearance of a dark colony color on BiGGY agar and H 2 S production in synthetic juice media. Sixteen null mutations were identified as leading to the production of increased levels of H 2 S in synthetic juice using the headspace analysis assay. All 16 mutants also produced H 2 S in actual juices. Five of these genes encode proteins involved in sulfur containing amino acid or precursor biosynthesis and are directly associated with the sulfate assimilation pathway. The remaining genes encode proteins involved in a variety of cellular activities, including cell membrane integrity, cell energy regulation and balance, or other metabolic functions. The levels of hydrogen sulfide production of each of the 16 strains varied in response to nutritional conditions. In most cases, creation of multiple deletions of the 16 mutations in the same strain did not lead to a further increase in H 2 S production, instead often resulting in decreased levels.

New Insights into Sulfur Metabolism in Yeasts as Revealed by Studies of Yarrowia lipolytica

“…We confirm here that H 2 S production strongly depends on sulfur supply, not on differences in the biosynthesis pathway. In wine, where sulfate is predominant, H 2 S is produced through the sulfate assimilation pathway (30,31). In contrast, in cheese, where sulfur is retrieved mainly in methionine and cysteine, the production of H 2 S could arise from cysteine catabolism (9,32).…”

Origins of Grape and Wine Aroma. Part 1. Chemical Components and Viticultural Impacts

“…However, it is hypothesized that under the anaerobic conditions experienced during fermentation, cysteine concentrations may play a more important regulatory role in sulfate reduction (Linderholm et al 2008). It has been shown that yeast respond to the addition of cysteine by increasing the production of H 2 S in preference to methionol while the addition of methionine results in an increase in methionol in preference to H 2 S (Moreira et al 2002).…”

“…Hydrogen sulfide production varies across yeast strains and with the nitrogen status of the juice (Acree et al 1972, Schutz and Kunkee 1977, Giudici and Kunkee 1994, Rauhut et al 1996, Jiranek et al 1995, Sea et al 1998, Bell and Henschke 2005, Linderholm et al 2008, Kumar et al 2010. It is generally understood that the addition of nitrogen, in the form of amino acids, with the exception of cysteine, or ammonium, reduces the production of H 2 S by yeast.…”

“…It is generally understood that the addition of nitrogen, in the form of amino acids, with the exception of cysteine, or ammonium, reduces the production of H 2 S by yeast. That is because these sources of nitrogen are precursors for O-acetylserine or O-acetylhomoserine synthesis, which are important in the synthesis of cysteine, methionine, and glutathione (Giudici and Kunkee 1994, Jiranek et al 1995, Linderholm et al 2008. The activity of Oacetylserine/O-acetylhomoserine sulfhydrylase (the enzyme responsible for incorporating reduced sulfur into organic compounds) is not the only factor important for reducing H 2 S production, but rather the activity of a complement of enzymes involved in the synthesis of O-acetyl-L-homoserine and homocysteine can help to reduce H 2 S production in S. cerevisiae (Spiropoulos andBisson 2000, Linderholm et al 2008).…”

Identification ofMET10-932and Characterization as an Allele Reducing Hydrogen Sulfide Formation in Wine Strains ofSaccharomyces cerevisiae

“…A screen of the deletion set of S. cerevisiae strains showed four possible mutations resulting in white colonies, and the relevant genes all encoded components of sulfite reductase (22) and were therefore candidate genes for the mutation in UCD932. The sulfite reductase enzyme complex is composed of catalytic and regulatory subunits.…”