开菲尔粒中主要组成菌的分离鉴定及微囊化纯培养混合发酵指标分析

Screening of main microorganism from Kefir Grain and analysis of femented milk using mixed microsapsule pure cultures

开菲尔粒是一个复杂的微生物共生体系,包含很多有益生作用的微生物。本文研究了一种开菲尔粒的主要组成菌并制成发酵剂。通过形态学特征初步分离纯化得出:该开菲尔粒样品主要由两株酵母菌、三株乳酸菌以及两株醋酸菌构成。经16S r DNA序列分析进一步确定其种属,得出其分别为Kluyveromyces marxianus和Pichia kudriavzevii、Lactobacillus pontis和Lactobacillus kefiri、Acetobacter lovaniensis和Acetobacter cibinongensis。采用分离出的菌株纯培养微囊化之后进行混合发酵,得到具有优良稳定发酵性能的混合发酵剂,测定结果显示发酵乳的营养成分、挥发性成分和抑菌性与原粒对比十分接近。

Kefir grain, as a complex system of microbial symbiosis, contains many useful microorganisms. The research focused on the main microbial composition of kefir grains and the preparation of a microbial starter culture.According to the colony forms and biological properties, the kefir grain samples were consisted of two strains of yeast, three strains of lactic acid bacteria （LAB） and two strains of acetic acid bacteria （ AAB）. After sequencing the 16S rDNA sequence of the seven strains, it can be concluded that the yeasts were identified as Kluyveromyces marxianus and Pichia kudriavzevii, LAB were Lactobacillus pontis and Lactobacfllus kefiri, AAB were Acetobacter Iovaniensis and Acetobacter cibinongensis. Further, the isolated strains were cultivated and microencapsulated.After the microcapsules were mixed and fermented in milk,the performance of the nutrition contents and volatile components and the property of antimicrobial activity were very similar to the original kefir grains.