永川毛霉型豆豉在发酵过程中菌群动态变化规律

Dynamic Change Rule of Microflora in Yongchuan Mucor-type Fermented Soya Beans During Fermentation

永川豆豉是重庆地区的特色传统发酵食品,具有丰富的营养价值。永川豆豉属于开放式制曲、多菌系发酵,豆豉菌群的动态变化一直以来是研究的热点。实验采用PCR-DGGE技术(变性梯度凝胶电泳)对永川毛霉型豆豉发酵过程中真菌和细菌群落的动态变化进行了研究。结果表明:在真菌水平上,制曲阶段总状毛霉(Mucor racemosus)占绝对优势,同时也有匍枝根霉(Rhizopus stolonifer)等辅助发酵,后发酵阶段有假丝酵母(Candida sp.)等酵母菌的参与。在细菌水平上,制曲阶段乳酸乳球菌属(Lactococcus lactis)生长占优势,拌料后其丰度急剧减少,而枯草芽孢杆菌(Bacillus subtilis)等成为新的优势菌株。发酵过程中也出现了一些杂菌,说明开放式制曲的发酵方式会有引入杂菌的安全隐患。

Yongchuan fermented soya beans are traditional fermented food with rich nutritional value in Chongqing.Yongchuan fermented soya beans belong to open-type koji making and multi-strain fermentation.The dynamic change of flora of fermented soya beans has always been a research hotspot.In this study,PCR-DGGE technology(denaturing gradient gel electrophoresis)is used to study the dynamic changes of fungi and bacterial communities during the fermentation of mucor-type Yongchuan fermented soya beans.The results show that the most dominant fungus is Mucor racemosus during koji-making stage,along with Rhizopus stolonifer and etc..Candida grows vigorously during post-fermentation stage.On the bacterial level,Lactococcus lactis grows predominantly in the koji-making stage,and its abundance decreases sharply after mixing,while Bacillus subtilis becomes new dominant strain.There are also some fungi in the process of fermentation,which indicates that the open-type koji-making fermentation method has the potential safety hazard of introducing sundry fungi.