浓香型大曲中产香微生物的筛选及鉴定

Screening and Identification of Aroma-producing Microorganisms in Luzhou-flavor Daqu

摘要:

本研究从传统浓香型大曲微生物资源中筛选产香功能性微生物，研究其与大曲香味物质之间的联系，并对产香功能菌株进行分子生物学鉴定。采用传统微生物分离法从不同发酵阶段的浓香型大曲中分离纯化获得细菌22株，酵母6株。以小麦固体培养基为底物对各细菌、酵母菌株进行单菌产香实验，经闻香评价，菌株X19和J3发酵后能产生浓郁的香味。采用顶空固相微萃取-气相色谱-质谱联用技术对这两株菌的发酵产物进行挥发性成分检测，发现菌株X19和J3的发酵产物中香味物质种类丰富，其中吡嗪类物质、苯乙醇、愈创木酚等香味物质为浓香型大曲的重要香味成分。因此，可初步认定菌株X19和J3为浓香型大曲的产香功能菌。经形态学观察和分子生物学鉴定，菌株X19为地衣芽孢杆菌（Bacillus licheniformis），菌株J3为异常威克汉姆酵母（Wickerhamomyces anomalus）。

Abstract:

Aroma-producing microorganisms were screened from traditional Luzhou-flavor daqu microbial resources. The relationship between aroma-producing microorganisms and flavoring substances in Luzhou-flavor daqu was also investigated. Functional aroma-producing microorganisms were identified using various molecular biology techniques. Multiple strains of bacteria (22) and yeast (6) were isolated and purified from the various fermentation stages of Luzhou-flavor daqu by traditional microbial separation. The bacterial and yeast strains were separately cultured in wheat solid growth medium, and tested for single-strain aroma production. The individual strains X19 and J3 were observed to produce rich flavors post-fermentation by a sensory evaluation (smell test). The volatile components present in the fermentation products of the two strains were identified by headspace solid phase micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS). This analysis identified a number of flavor substances in the fermentation products of the two strains. Among these, pyrazine, phenylethanol, and guaiacol were identified as important flavor substances present in Luzhou-flavor daqu. Therefore, the two strains were primarily identified as the functional aroma-producing microorganisms present in Luzhou-flavor daqu. Morphological observation and molecular biology identification analyses have identified the X19 and J3 strains as types of Bacillus licheniformis and Wickerhamomyces anomalus, respectively.