在酱油发酵过程中,微生物在风味形成中起着至关重要的作用。不同的酱油发酵类型显著影响风味形成。然而,不同发酵类型之间的微生物群落和代谢产物的比较研究很少。这里,我们调查了微生物群落的变化,代谢物谱,日式(JP)和粤式(CP)发酵过程中的代谢途径。发酵类型之间的游离氨基酸和挥发性化合物分布差异显着,JP样品含有较高的酯含量(39.84%;p<0.05),120d发酵样品中的酒精含量(44.70%;p<0.05)。发酵类型之间的挥发性化合物分布差异显著,JP样品含有较高含量的酯,酒精,和游离氨基酸(p<0.05)。宏基因组分析表明,JP和CP群落均以四球菌为主,葡萄球菌,Weissella(细菌),和曲霉(真菌),但是随着时间的推移,这两个社区的变化有所不同。在JP发酵的整个发酵过程中,四球菌的丰度急剧增加(从0.02%到59.2%),在CP发酵中,四球菌(36.7%)和葡萄球菌(29.7%)在发酵120d时占主导地位。宏基因组功能谱显示,大多数与碳水化合物有关的基因的丰度,氨基酸,在发酵中后期,发酵类型之间的脂质代谢表现出显著差异(p<0.05)。此外,预测的挥发性物质生物合成的代谢途径在JP和CP发酵之间有所不同,可能解释了风味代谢物谱的差异。此外,与风味产生相关的大多数基因与四球菌属有关,Weissella,葡萄球菌,芽孢杆菌,和曲霉,这表明这些微生物在酱油发酵过程中的风味产生中起着重要作用。这项研究大大提高了我们对不同酱油发酵过程中微生物功能及其在风味形成中的代谢作用的理解。
Microorganisms play essential roles in flavor formation during soy sauce fermentation. Different soy sauce fermentation types significantly affect flavor formation. However, comparisons of microbial communities and metabolites between different fermentation types have been little studied. Here, we investigated variation in microbial communities, metabolite profiles, and metabolic pathways during Japanese-type (JP) and Cantonese-type (CP) fermentation. Free amino acids and volatile compound profiles varied significantly between fermentation types, with JP samples containing higher contents of esters (39.84%; p < 0.05), alcohols (44.70%; p < 0.05) in the 120 d fermentation samples. Volatile compound profiles varied significantly between fermentation types, with JP samples containing higher contents of esters, alcohols, and free amino acids (p < 0.05). Metagenomic analysis indicated that both JP and CP communities were dominated by Tetragenococcus, Staphylococcus, Weissella (bacteria), and Aspergillus (fungi), but the two communities varied differently over time. Tetragenococcus drastically increased in abundance throughout the fermentation (from 0.02 to 59.2%) in JP fermentation, whereas Tetragenococcus (36.7%) and Staphylococcus (29.7%) dominated at 120 d of fermentation in CP fermentation. Metagenomic functional profiles revealed that the abundances of most genes involved with carbohydrate, amino acid, and lipid metabolism exhibited significant differences between fermentation types (p < 0.05) during the middle to late fermentation stages. Furthermore, predicted metabolic pathways for volatile substance biosynthesis differed between JP and CP fermentation, likely explaining the differences in flavor metabolite profiles. In addition, most of the genes associated with flavor generation were affiliated with Tetragenococcus, Weissella, Staphylococcus, Bacillus, and Aspergillus, suggesting that these microbes play important roles in flavor production during soy sauce fermentation. This study significantly improves our understanding of microbial functions and their metabolic roles in flavor formation during different soy sauce fermentation processes.