内蒙古和新疆牧区酸马奶中酵母菌的多样性及其优势菌发酵特性

Diversity and Fermentation Characteristics of Yeasts in Koumiss Collected from Inner Mongolia and Xinjiang

探究内蒙古和新疆牧区传统酸马奶中酵母菌的多样性及其优势菌的发酵特性,依据GB 4789.15—2010《食品微生物学检验霉菌和酵母计数》进行菌株分离,再应用26S rDNA D1/D2区序列和内转录间隔区（internal transcribed space,ITS）序列分析技术鉴定分离株,并依据产酒精能力、产酸能力、风味及质构特性等指标筛选优良菌株。结果表明：1）内蒙古酸马奶样品中酵母菌活菌数为10^5 CFU/mL,新疆样品在10^5-10^7 CFU/mL之间。两地样品中共鉴定出包括Kluyveromyces marxianus、Pichia fermentans、Pichia cactophila、Candida zeylanoides在内的酵母菌13种。两地间样品酵母菌组成不尽相同,具有地区差异性,内蒙古优势菌为Kluyveromyces marxianus、Pichia cactophila和Pichia fermentans,新疆优势菌为Candida zeylanoides和Kluyveromyces marxianus。2）优选出的4株酵母菌有2株为Pichia cactophila,另外2株为Kluyveromyces marxianus和Candida zeylanoides,发酵特性良好,可用于新型发酵乳制品开发。

The aim of this study was to analyze the diversity and fermentation characteristics of the yeasts in koumiss collected from Inner Mongolia and Xinjiang. After isolation and purification, the yeasts were identified by 26 S rDNA and ITS sequences. Excellent yeasts were selected according to alcohol yield, acid yield, texture and sensory evaluation. The results indicated that the number of yeast colonies in koumiss from Inner Mongolia was 10~5 CFU/mL, while the number of yeast colonies in koumiss from Xinjiang samples ranged from 10^5 to 10^7 CFU/mL. Thirteen species including Kluyveromyces marxianus, Pichia fermentans, Pichia cactophila and Candida zeylanoides were identified. The compositions of yeast species in koumiss samples from different regions were different. In Inner Mongolia samples, nine species were identified with the dominant species being Kluyveromyces marxianus, Pichia cactophila and Pichia fermentans. In Xinjiang samples, the dominant species were Kluyveromyces marxianus and Candida zeylanoides. Four excellent yeast strains including two strains of Pichia cactophila, one strain of Kluyveromyces marxianus and one strain of Candida zeylanoides were selected. They all had excellent fermentation characteristics and could be used in the production of novel fermented dairy products.