The influence of nitrogen and biotin interactions on the performance of Saccharomyces in alcoholic fermentations

Abstract

Aim: To study the impact of assimilable nitrogen, biotin and their interaction on growth, fermentation rate and volatile formation by Saccharomyces. Methods and Results: Fermentations of synthetic grape juice media were conducted in a factorial design with yeast assimilable nitrogen (YAN) (60 or 250 mg l−1) and biotin (0, 1 or 10 μg l−1) as variables. All media contained 240 g l−1 glucose + fructose (1 : 1) and were fermented using biotin‐depleted Saccharomyces cerevisiae strains EC1118 or UCD 522. Both strains exhibited weak growth and sluggish fermentation rates without biotin. Increased nitrogen concentration resulted in higher maximum fermentation rates, while adjusting biotin from 1 to 10 μg l−1 had no effect. Nitrogen × biotin interactions influenced fermentation time, production of higher alcohols and hydrogen sulfide (H2S). Maximum H2S production occurred in the medium containing 60 mg l−1 YAN and 1 μg l−1 biotin. Conclusions: Nitrogen × biotin interactions affect fermentation time and volatile production by Saccharomyces depending on strain. Biotin concentrations sufficient to complete fermentation may affect the organoleptic impact of wine. Significance and Impact of the Study: This study demonstrates the necessity to consider nutrient interactions when diagnosing problem fermentations.

The production of hydrogen sulphide and other aroma compounds by wine strains of Saccharomyces cerevisiae in synthetic media with different nitrogen concentrations

“…The wine strain EC1118 seems to be a poor-nitrogen responder in a range of 66-402 mg N l ¡1 , as no remarkable H 2 S was detected under all experimental conditions. This strain has shown the ability to produce higher amounts of H 2 S in response to nitrogen status during alcoholic fermentation using synthetic grape juice media [5,43]. The discrepancy between H 2 S liberation observed in this work compared with earlier studies could have various explanations.…”

“…Data are the mean from triplicate fermentations § SD work. Additionally, the former studies were performed under vitamin deWciency conditions [5,43]. The amounts of pantothenic acid (10, 50 and 250 g l ¡1 ) [43] and biotin (0, 1 and 10 g l ¡1 ) [5] used in those studies could have stimulated H 2 S liberation.…”

“…Thus, the rate of H 2 S formation seems to be regulated by cellular demands for sulphur amino acids and maintenance of intracellular nitrogen pools [12]. Several environmental and nutritional factors have been associated with H 2 S production under winemaking conditions, namely (1) levels of elemental sulphur [29,34] naturally available as sulphate at an average concentration of 200 mg l ¡1 [24], (2) presence of sulphur dioxide [1,32] commonly added (50-200 mg l ¡1 ) to grape must prior to wine fermentation, (3) presence of organic compounds containing sulphur [2], and (4) vitamin deWciency [5,36,42,43]. Yet, poor correlations between H 2 S formation and assimilable nitrogen have been reported [30,41].…”

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

“…Growth conditions also impact the appearance and retention of H 2 S. Environmental and nutritional factors, such as levels of elemental sulfur (36), the presence of sulfur dioxide (44,49) or organic compounds containing sulfur (1), nitrogen limitation (12,19,25), and vitamin deficiency (5,50,52,54), have been associated with the production of volatile sulfur compounds. Not surprisingly, strains respond differently to these variations in growth conditions, with some producing little or no H 2 S regardless of the condition and others producing high levels likewise regardless of the conditions (20).…”

The role ofGAP1gene in the nitrogen metabolism ofSaccharomyces cerevisiaeduring wine fermentation

“…This NCR condition inhibited the uptake of arginine and alanine and stimulates the consumption of branched-chain and aromatic amino acids. Changes in the nitrogen uptake patterns influence the production of aroma and spoilage compounds (especially hydrogen sulfide) and the amount of urea, the major precursor to the carcinogen ethyl carbamate (Marks et al 2003;Beltran et al 2005;Bohlscheid et al 2007).…”