Effect of citrulline metabolism inSaccharomyces cerevisiaeon the formation of ethyl carbamate during Chinese rice wine fermentation

Abstract

Urea, as the main precursor of ethyl carbamate (EC), has received extensive attention. Here, we have metabolically engineered an industrial yeast strain – Saccharomyces cerevisiae N85 – to investigate the contribution of the EC precursor citrulline to the concentration of EC in Chinese rice wine. The results showed that the citrulline biosynthetic pathway of the modified strain N85‐arg3 was completely suppressed by deletion of ARG3, encoding ornithine carbamoyltransferase. However, there were no significant differences in the levels of citrulline or EC between N85‐arg3 and the parental strain N85 during fermentation. In addition, we over‐expressed ARG1 (encoding argininosuccinate synthase) and ARG4 (encoding argininosuccinate lyase) to construct the engineered strains N85ARG1,4 and N85ARG1,4‐arg3. The citrulline contents in Chinese rice wine fermented with N85ARG1,4 and N85ARG1,4‐arg3 were respectively 24.1 and 20.4% less than that of N85. However, the contents of EC were 23.8 and 28.5% more than that of N85. These results suggested that reducing the formation of EC during Chinese rice wine fermentation by genetically engineering citrulline metabolism in S. cerevisiae was not a viable proposition. Copyright © 2018 The Institute of Brewing & Distilling

Occurrence of Ethyl Carbamate in Foods and Beverages: Review of the Formation Mechanisms, Advances in Analytical Methods, and Mitigation Strategies

“…These redundancies often require suppression of multiple genes to reduce synthesis of target compounds (203). For example, no differences in EC concentrations were observed in rice wine fermented using genetically engineered yeast with reduced capacity to synthesize citrulline (202). Guo et al (73) found that deletion of one copy of the CAR1 gene in S. cerevisiae reduced EC formation in rice wine by only ca.…”

Research progress on the application of different controlling strategies to minimizing ethyl carbamate in grape wine

“…Although citrulline is also an EC precursor, Wu et al (2018) constructed genetically engineered strain N85 by overexpressing Arg1-encoding argininosuccinate synthase and Arg4-encoding argininosuccinate lyase, as well as silencing Arg3 encoding the ornithine carbamoyl transferase strain N85-Arg3 was constructed. The results showed that compared with the parental strains, N85 and N85-Arg3 reduced the citrulline content by 24.1% and 20.45%, respectively, but increased the EC content by 23.8% and 28.5%, respectively (Wu et al, 2018). These results suggest that genetically engineering the yeast citrulline metabolism to reduce EC formation is not a viable option (Wu et al, 2018).…”

Nature’s Most Fruitful Threesome: The Relationship between Yeasts, Insects, and Angiosperms

“…Floral nectar can also contain glycoconjugates formed by monosaccharides bound (especially through a ß-glucosidic linkage) to aromatic compounds (aglycones), such as geraniol [ 83 , 84 ], α-terpineol [ 85 , 86 ], methyl salicylate [ 85 , 87 ], 1-hexanol [ 88 , 89 ], eugenol [ 59 , 90 ], vanillin, and vanillyl alcohol [ 91 , 92 , 93 ]. When these glycoconjugates are hydrolyzed by yeast glucosidases, their aglycones volatilize [ 94 , 95 , 96 , 97 , 98 ], working as attractive or repelling agents for insects (see Section 3 ).…”

“…About 250 NPAAs have already been found in plants, especially in the families Fabaceae, Sapindaceae, and Cucurbitaceae [ 114 ]. Although NPAAs play central physiological roles in plants, mainly as bioactive compounds (acting as antiherbivore, antimicrobial, antioxidant, and/or growth-promoting agents), some of these amino acids are known to be metabolized by yeasts, namely, taurine [ 115 ], β-alanine [ 116 , 117 ], citrulline [ 89 , 118 ], ornithine [ 119 ], γ-aminobutyric acid (GABA) [ 120 , 121 ], hydroxytryptophan [ 122 ], selenocysteine [ 123 ], methionine sulfoxide [ 124 ], serotonin [ 125 ], and dopamine [ 126 ]. Despite the lack of studies regarding VOC production from NPAAs by nectar microbes, it is likely that some of them (especially those with S-containing side chains) are converted into volatile compounds by yeast cells [ 127 ].…”