Affiliation:
1. Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
2. Zhejiang Guyuelongshan Shaoxing Wine Company, Shaoxing, Zhengjiang, China
Abstract
ABSTRACT
Rice wine has been one of the most popular traditional alcoholic drinks in China. However, the presence of potentially carcinogenic ethyl carbamate (EC) in rice wine has raised a series of food safety issues. During rice wine production, the key reason for EC formation is urea accumulation, which occurs because of nitrogen catabolite repression (NCR) in
Saccharomyces cerevisiae
. NCR represses urea utilization by retaining Gln3p in the cytoplasm when preferred nitrogen sources are present. In order to increase the nuclear localization of Gln3p, some possible phosphorylation sites on the nuclear localization signal were mutated and the nuclear localization regulation signal was truncated, and the disruption of
URE2
provided an additional method of reducing urea accumulation. By combining these strategies, the genes involved in urea utilization (
DUR1,2
and
DUR3
) could be significantly activated in the presence of glutamine. During shake flask fermentations of the genetically modified strains, very little urea accumulated in the medium. Furthermore, the concentrations of urea and EC were reduced by 63% and 72%, respectively, in a model rice wine system. Examination of the normal nutrients in rice wine indicated that there were few differences in fermentation characteristics between the wild-type strain and the genetically modified strain. These results show that metabolic engineering of the NCR regulators has great potential as a method for eliminating EC during rice wine production.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
35 articles.
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