Background Wine yeasts can produce undesirable sulfur compounds during alcoholic fermentation,

Background Wine yeasts can produce undesirable sulfur compounds during alcoholic fermentation, such as SO2 and H2S, in variable amounts depending mostly within the candida strain but also within the conditions. a metabolic intermediate, O-acetylhomoserine, whereas affects the activity of a key enzyme of the sulfur assimilation branch of the pathway, the APS kinase, encoded by and genes, that control the activity of both branches of the sulfur Thymosin b4 manufacture amino acid synthesis pathway and modulate sulfite/sulfide Mouse monoclonal to Calcyclin production and additional related phenotypes. These results provide novel focuses on for the improvement of wine candida strains. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0245-1) contains supplementary material, which is available to authorized users. to their promoter and its association with auxiliary factors, Met28p, Cbf1p, Met31p and Met32p [8-11]. is definitely controlled through an inhibitory mechanism mediated by [12], which encodes an F-box protein that is portion of an ubiquitin-proteasome complex [13,14]. This complex focuses on Met4p for degradation from the proteasome depending on the intracellular concentration of cysteine [15]. Furthermore, Natarjan [16] showed that several genes of sulfur rate of metabolism are also controlled by and and [17] recognized a new mechanism involving the F-box protein skp2p, which forms portion of a complex, SCFand genes. The production of sulfites and sulfide depends on environmental factors including the concentration of nutrients in the press, and Thymosin b4 manufacture in particular that of nitrogen-containing compounds (ammonium, amino acids and especially sulfur-containing amino acids). Nitrogen concentration affects in a different way the production of SO2 and H2S: SO2 production is definitely favored in the presence of high nitrogen concentrations [18], whereas H2S production is definitely favored Thymosin b4 manufacture in nitrogen-deficient musts [19-21]. Supplementation with amino acids and/or ammonium can significantly impact SO2 and H2S production depending on the amount of added compound and the time of addition [19,20,22]. SO2 and H2S production is also affected by the concentration of sulfates and vitamins, such as pantothenate, and by pH and probably several other factors [23-26]. However, the largest source of variance in the production of sulfur compounds is the candida strain itself. Wine yeasts create sulfites at concentrations ranging from less than 10?mg/L to more than 100?mg/L [24]. Similarly, sulfide production is definitely undetectable for some strains whereas additional strains produce high amounts of sulfide [27,28]. Several genes involved in sulfur metabolism have been implicated Thymosin b4 manufacture in the ability of strains to produce sulfite and/or sulfide, suggesting that this phenotypic property is definitely controlled by multiple genetic loci. Several studies have examined the effect of the deletion or the overexpression of genes of the sulfur assimilation pathway [29-32]. Some studies have also focused on variants of genes of the sulfur assimilation pathway that impact hydrogen sulfide formation, and in particular on variants of sulfite reductase, to identify mutants showing problems in the conversion of sulfite into sulfide [5,33,34]. However, the molecular basis responsible for variations in the production of sulfur compounds, and Thymosin b4 manufacture in particular that of sulfite, between candida strains is still not fully recognized. In this study, we used a QTL mapping strategy to search for genes responsible for phenotypic variance in SO2 and H2S production between candida strains. This genetic approach is now widely used to study continuous phenotypes and has been successfully applied to several wine candida traits, including complex qualities governed by several loci [35-38]. We focused on two wine candida strains; a high sulfite-producing strain and a low sulfite-producing strain. We built and characterized a human population of recombined meiotic segregants to perform linkage analysis. This analysis exposed a double QTL on chromosome XIV comprising two genes involved in sulfur rate of metabolism, and strains, both of which were homozygous diploid derivatives of wine yeasts, which were previously shown to differ in their ability to create sulfite: JN10, a high sulfite-producing strain, and JN17, a low sulfite-producing strain. We characterized the sulfite production of these two strains inside a synthetic must under conditions that favor sulfite production: a high nitrogen content (425?mg/L) and a low temperature.