顶温对特香型大曲理化指标及菌群演替的影响

Effect of peak temperature on the succession of physicochemical index andmicrobial community of Special-flavor Daqu

以特香型白酒大曲为研究对象,跟踪分析不同顶温大曲在制作过程中理化指标及菌群结构的变化规律。结果表明,中顶温曲(BM)和高顶温曲(BH)在发酵过程中的温度、水分、酸度及还原糖变化存在一定差异;Illumina MiSeq结果表明,魏斯氏菌属(Weissella)和乳杆菌属(Lactobacillus)分别为BM和BH发酵过程中的优势细菌。嗜热子囊菌属(Thermoascus)和假丝酵母属(Candida)为BH和BM的优势真菌,且发酵通过顶温区后,二者在BH中的相对丰度高于BM。同时发现Weissella、Lactobacillus、片球菌属(Pediococcus)和芽孢杆菌(Bacillus)是对大曲酸度、酸性蛋白酶活力产生重要影响的细菌。出房时BM的酸性蛋白酶活力、糖化力及酯化力均高于BH,可能与根毛霉(Rhizomucor)、红曲霉(Monascus)和曲霉属(Aspergillus)等丝状真菌相对丰度变化有关。

The changes of physiochemical indexes and microbial community structure of two different-peak-temperature batches of Special-flavor Daqu were tracked during their production process.There were certain differences in the changes of temperature,moisture,acidity and reducing sugar in the fermentation process of high top temperature(BH)Daqu and medium top temperature(BM)Daqu.The results of Illumina MiSeq sequencing showed that Weissella and Lactobacillus were the dominant bacterial genus in the whole fermentation processes of BM and BH,respectively.In terms of fungi,Thermoascus and Candida were the dominant fungi genus of BM and BH,and after the peak temperature zone,their relative abundances of BH were higher than those of BM.It was also found that Weissella,Lactobacillus,Pediococcus and Bacillus were the bacterium which had significant influences on the acidity and acid protease activity of Daqu.Moreover,the acid protease activity,saccharifying power and esterifying power of BM were higher than those of BH by the end of fermentation,which may be related to the relative abundance change of filamentous fungi such as Rhizomucor,Monascus and Aspergillus.