酱香型白酒第2、3轮次堆积发酵有机酸代谢规律与菌群结构及其相关性解析

Microbial Community Structure and Organic Acid Metabolism and Their Correlation in the Second and Third Rounds of Stacking Fermentation of Sauce-Flavor Baijiu

本实验以酱香型白酒优势产酒轮次(即第3、4轮次基酒所对应的第2、3轮次)堆积发酵过程中的酒醅为研究对象,采用高效液相色谱和高通量测序等技术对酒醅中的有机酸及菌群结构进行分析,探讨堆积发酵过程中有机酸与微生物群落之间的互作关系。结果表明,堆积发酵酒醅中主要有机酸为乳酸(32.70 mg/g,醅样内平均含量,后同)、乙酸(4.87 mg/g)和琥珀酸(1.93 mg/g)。第2、3轮次堆积发酵酒醅中共有8个优势细菌属和7个优势真菌属(平均相对丰度>1%),细菌的优势菌属主要为枝芽孢杆菌属(Virgibacillus)、克罗彭斯特菌属(Kroppenstedtia)和芽孢杆菌属(Bacillus);真菌的优势菌属主要为红曲霉属(Monascus)、嗜热真菌属(Thermomyces)和嗜热子囊菌属(Thermoascus)。主坐标分析表明,第2、3轮次堆积发酵细菌群落结构存在显著差异,真菌差异不显著。共现性网络分析表明,细菌-真菌(55.60%)、细菌-细菌(50.57%)和真菌-真菌(91.67%)网络均以正相关为主,且细菌-细菌群落之间存在更多的未知互作关系。Mantel test分析表明,酸度与细菌群落结构呈极显著正相关(P<0.01),且琥珀酸是与细菌和真菌群落演替均呈极显著相关的有机酸(P<0.01)。Spearman相关性分析表明,细菌与有机酸的显著相关关系多于真菌,真菌与绝大多数的有机酸呈负相关,除柠檬酸外,其他9种有机酸都与海洋芽孢杆菌属(Oceanobacillus)、芽孢杆菌属、鞘氨醇杆菌属(Sphingobacterium)呈正相关,与高温放线菌属(Thermoactinomyces)呈负相关。研究结果可为优质酱酒的生产调控提供一些理论基础。

The organic acids and microbial community structure of fermented grains in the dominant stacking fermentation rounds for sauce-flavor Baijiu production(i.e.,the 2nd and 3rd rounds corresponding to the 3rd and 4th rounds of base liquor)were analyzed using high-performance liquid chromatography(HPLC)and high-throughput sequencing,and the interaction between them was investigated.The results revealed that lactic acid,acetic acid,and succinic acid were the primary organic acids present in fermented grains at mean values of 32.70,4.87 and 1.93 mg/g,respectively.In total,8 dominant bacterial genera and 7 dominant fungal genera(average relative abundance>1%)were identified across the two fermentation rounds.The dominant bacterial genera were Virgibacillus,Kroppenstedtia and Bacillus.The dominant fungal genera were Monascus,Thermomyces and Thermoascus.Principal coordinate analysis(PCoA)revealed that there was a significant difference in the structure of bacteria community between the second and third rounds of stacking fermentation,while the difference in the structure of fungal community was not significant.Co-occurrence network analysis showed that the bacterial-fungal(55.60%),bacterial-bacterial(50.57%),and fungal-fungal(91.67%)networks were mainly positively correlated,and there were more unknown interactions between bacterial communities.Mantel test analysis showed a significantly positive correlation between acidity and bacterial community structure(P<0.01),and succinic acid was highly correlated with both bacterial and fungal community succession(P<0.01).Spearman’s correlation analysis revealed that the bacterial community had a more significant correlation with organic acids than the fungal community,while the fungal community showed a negative correlation with most organic acids.Nine organic acids citric acid were positively correlated with Oceanobacillus,Bacillus,and Sphingobacterium but negatively correlated with Thermoactinomyces.The results of this study can provide a theoretical basis for the production of high-quality sauce-flavor Baijiu.