US EPA

7424285 

Journal Article 

Urea production by yeasts other than Saccharomyces in food fermentation 

Wu, Q; Cui, K; Lin, J; Zhu, Y; Xu, Y; , 

2017 

Yes 

F E M S Yeast Research
ISSN: 1567-1356
EISSN: 1567-1364 

OXFORD UNIV PRESS 

OXFORD 

17 

7 

English 

29040547 

10.1093/femsyr/fox072 

WOS:000416721200013 

http://academic.oup.com/femsyr/article/doi/10.1093/femsyr/fox072/4411803
Exit
 

Urea is an important intermediate in the synthesis of carcinogenic ethyl carbamate in various food fermentations. Identifying urea-producing microorganisms can help control or reduce ethyl carbamate production. Using Chinese liquor fermentation as a model system, we identified the yeasts responsible for urea production. Urea production was positively correlated to the yeast population (R = 0.523, P = 0.045), and using high-throughput sequencing, we identified 26 yeast species. Partial least squares regression and correlation analysis indicated that Wickerhamomyces anomalus was the most important yeast to produce urea (variable importance plot = 1.927; R = 0.719, P = 0.002). Besides, we found that in W. anomalus the CAR1 gene (responsible for urea production) was 67% identical to that of Saccharomyces cerevisiae. Wickerhamomyces anomalus produced more urea (910.0 μg L-1) than S. cerevisiae (300.1 μg L-1). Moreover, urea production increased to 1261.2 μg L-1 when the two yeasts were co-cultured in a simulated fermentation, where the transcription activity of the CAR1 gene increased by 140% in W. anomalus and decreased by 40% in S. cerevisiae. Our findings confirm that a yeast other than Saccharomyces, namely W. anomalus, contributes more to urea formation in a simulated sorghum fermentation. These findings provide the basis for strategies to control or reduce ethyl carbamate formation. 

Chinese liquor; Ethyl carbamate; Food fermentation; Saccharomyces cerevisiae; Urea; Wickerhamomyces anomalus; DNA 26S; fungal DNA; genomic DNA; urea; urethan; urea; ACT1 gene; Article; Candida; Candida albicans; Candida humilis; Candida parapsilosis; Candida phayaonensis; Candida tropicalis; Candida zeylanoides; CAR1 gene; Clavispora lusitaniae; coculture; community structure; controlled study; Cryptococcus albidus; Cryptococcus podzolicus; Cryptococcus victoriae; fermentation; fermented product; Filobasidiella; food processing; fungal gene; fungus culture; gene sequence; genetic transcription; Hanseniaspora osmophila; high throughput sequencing; Kazachstania; Kazachstania bulderi; Kodamaea ohmeri; Meyerozyma guilliermondii; Millerozyma farinosa; Naumovozyma castellii; nonhuman; nucleotide sequence; Pichia; Pichia fermentans; Pichia kluyveri; Pichia kudriavzevii; Pichia manshurica; Pichia membranifaciens; Rhodotorula mucilaginosa; Saccharomyces cerevisiae; Saccharomycopsis fibuligera; sorghum; species composition; Trichosporon asahii; urea cycle; Wickerhamomyces anomalus; yeast; budding yeast; fermentation; food grain; genetics; metabolism; Saccharomyces; Edible Grain; Fermentation; Saccharomyces; Saccharomycetales; Sorghum; Urea