Du Hai, Song Zhewei, Xu Yan
The Key Laboratory of Industrial Biotechnology of the Ministry of Education, State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, School of Biotechnology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China.
J Agric Food Chem. 2018 Jan 10;66(1):387-392. doi: 10.1021/acs.jafc.7b05034. Epub 2017 Dec 21.
This study aimed to identify specific microorganisms related to the formation of precursors of EC (ethyl carbamate) in the solid-state fermentation of Chinese Moutai-flavor liquor. The EC content was significantly correlated with the urea content during the fermentation process (R = 0.772, P < 0.01). Differences in urea production and degradation were found at both species and functional gene levels by metatranscriptomic sequencing and culture-dependent analysis. Lactobacillus spp. could competitively degrade arginine through the arginine deiminase pathway with yeasts, and most Lactobacillus species were capable of degrading urea. Some dominant nonconventional yeasts, such as Pichia, Schizosaccharomyces, and Zygosaccharomyces species, were shown to produce low amounts of urea relative to Saccharomyces cerevisiae. Moreover, unusual urea degradation pathways (urea carboxylase, allophanate hydrolase, and ATP-independent urease) were identified. Our results indicate that EC precursor levels in the solid-state fermentation can be controlled using lactic acid bacteria and nonconventional yeasts.
本研究旨在确定与中国酱香型白酒固态发酵中氨基甲酸乙酯（EC）前体形成相关的特定微生物。发酵过程中EC含量与尿素含量显著相关（R = 0.772，P < 0.01）。通过宏转录组测序和培养依赖性分析，在物种和功能基因水平上均发现了尿素产生和降解的差异。乳酸杆菌属可通过精氨酸脱亚胺酶途径与酵母竞争性降解精氨酸，且大多数乳酸杆菌物种能够降解尿素。相对于酿酒酵母，一些优势非常规酵母，如毕赤酵母属、裂殖酵母属和接合酵母属物种产生的尿素量较低。此外，还鉴定出了不寻常的尿素降解途径（尿素羧化酶、脲基甲酸水解酶和不依赖ATP的脲酶）。我们的结果表明，固态发酵中的EC前体水平可通过乳酸菌和非常规酵母进行控制。
