大曲中两株产色素微生物的代谢及生态条件研究

Study on The Metabolism and Ecological Conditions of Two Pigment-producing Strains from Daqu

采用纯培养法从大曲中分离得到了2株产色素微生物。产红色素菌株A是一个与玫瑰红微球菌亲缘关系较近的革兰氏阳性球菌。有所不同的是，产红色素菌株A的耐热性更好，既能产淀粉酶又能产蛋白酶，还可以产生吲哚。在以葡萄糖作为碳源的查氏培养基上，32℃培养3～5 d，可产生大量的红色素。分子鉴定显示，菌株A与地衣芽孢杆菌的16S rRNA序列相似性超过了99%，而与微球菌的16S rRNA序列却有较大的差异。综合形态、生理和DNA特征，可以将菌株A鉴定为芽孢八叠球菌。产黄色素菌株B属于黄曲霉，具有较强的淀粉水解能力和较好的耐乙醇和耐酸性能力，在pH值为7.5的马铃薯液体培养基中摇床培养，可产生曲香。色素微生物对认识大曲颜色成因和改进制曲工艺具有重意义。

In this study, two pigment-producing strains were isolated from Daqu by pure cultivation. Red pigment-producing Strain A is a kind of gram-positive cocci similar to Micrococcus roseus, but it shows greater heat resistance than Micrococcus roseus, and it can produce amylase, pro-tease and indole. Cultured in Czapek medium for 3~5 days at 32℃, Strain A can produce large amounts of red pigment. Molecular identification showed that the similarity between the 16S rRNA sequence of Strain A and that of Bacillus licheniformis was more than 99%, while there were large differences between the 16S rRNA sequence of Strain A and that of Micrococcus roseus. Comprehensively considering the morphological, physiological and DNA characteristics, Strain A was identified as Bacillus sarcina. Yellow pigment-producing Strain B is a type of Aspergillus flavus, which has high starch hydrolysis ability and good ethanol and acid resistance. Cultured in liquid potato medium at pH 7.5, Strain B can produce Daqu flavour. The results of our study is of great importance to the understanding of the sources of the colours of Daqu, and to the im-provement of Daqu-making techniques. （Tran. by HUANG Xiaoli）.