Screening of <i>Aspergillus recifensis</i> EC-1 in Urea-Exposure Fermented Grains: Ethyl Carbamate Metabolic Mechanism, and Application Potential of the Degrading-Microbe and -Enzyme in <i>Baijiu</i>

Ethyl carbamate (EC) poses a potential public health risk; the reduction efficiency is limited by high ethanol and acidic conditions during fermentation. This study identified fungi as key EC-degrading microbes from <i>Baijiu</i> fermented grains. <i>Aspergillus recifensis</i>. EC-1 isolated from <i>Baijiu</i> fermented grains degraded 50.7% EC (5 g·L^-1) in 7 days. Transcriptomics and metabolomics revealed EC hydrolysis via amidase into ammonia and ethanol: ammonia entered arginine biosynthesis, while ethanol fueled central carbon metabolism. TR3859 was identified as degrading enzyme. It remained highly active under 20% ethanol and 15% NaCl conditions (9.1 U·mg^-1 and 38.8 U·mg^-1), and the enzyme's affinity for EC was <i>K</i>_m = 6.0 mM. When coculture with strain EC-1 and <i>Daqu</i>, EC degradation reached 81.5% within 3 days, and the relative abundance of the genera <i>Thermoascus</i> and <i>Thermomyces</i> exceeds 65%. The objective of this study was to provide an efficient method for EC elimination in fermented foods by microbes and enzymes.