【作者】 倪慧娟；

【导师】 张和平；

【作者基本信息】 内蒙古农业大学 ， 畜产品安全生产， 2009， 博士

【摘要】 对新疆地区和青海地区传统发酵乳制品中的酵母菌进行了分离及生理生化与分子生物学鉴定,同时对其中的酵母菌生物多样性进行了分析。本研究为进一步全面系统地了解新疆和青海地区传统发酵乳制品中的微生物组成提供了丰富的数据,以利于开发利用传统发酵乳制品中的酵母菌资源。新疆地区28份传统发酵酸马奶中的酵母菌总数在3.12×104-2.23×106CFU/mL之间,主要集中分布于105和106CFU/mL,相对于同一样品中分离出的乳酸菌数量低1-2个对数级。青海地区11份酸山羊奶样品中的酵母菌总数在2.07×105-1.63×108 CFU/mL之间,比同一样品中的乳酸菌总数低2-3个对数级。青海地区25份酸牦牛奶样品中的酵母菌总数在2.60×106-2.00×109CFU/mL之间,主要集中在107和108 CFU/mL。其中青海省海北州酸牦牛奶样品中的酵母菌总数比乳酸菌总数低1-2个对数级;海南州酸牦牛奶样品中的酵母菌总数高于或接近乳酸菌总数。新疆地区28份酸马奶样品中共分离到酵母菌87株,结合传统分类鉴定方法与26S rDNA序列分析方法对酵母菌进行鉴定。结果表明新疆地区发酵酸马奶中的酵母菌主要为Kazachstania unisporus 43株(占总分离株的49.4%)和Kluyveromyces marxianus 23株(26.4%),其他的酵母分离株分别是Saccharomyces cerevisiae 8株,Pichia membranaefaciens 2株,Pichia fermentans 6株,Pichia manshurica(Pichia galeiformis)2株和Pichia kudriavzevii(Issatchenkia orientalis)3株。将新疆酸马奶中酵母分离株的ITS扩增片段进行对比,通过菌株ITS区域之间的长度差异性对酸马奶中的酵母分离株进行分类,同时采用ITS序列分析的方法对酸马奶中部分酵母分离株进行鉴定。新疆不同地区酸马奶中酵母菌的种类和数量呈现出多样性。K. unisporus在高达22个酸马奶样品中出现。K. unisporus - Kl. marxianus的发酵组合是酸马奶中酵母菌的优势组合。S. cerevisiae和Pichia属的菌株在酸马奶样品中没有单独出现的情况。对青海地区传统发酵乳制品中的酵母菌进行鉴定。青海2个地区的25份酸牦牛奶样品中共分离出74株酵母菌,其中S. cerevisiae 20株,Kl. marxianus 18株, K. unisporus 1株,Candida zeylanoides 2株,Rhodotorula mucilaginosa 1株,以及Pichia属的P. fermentans 31株和P. kudriavzevii 1株。青海地区酸牦牛奶中酵母菌的优势菌为P. fermentans (43.2%)、S. cerevisia(e27.0%)和Kl. marxianu(s24.3%)。P. fermentans - Kl. marxianus、P. fermentans - S. cerevisiae,以及Kl. marxianus - S. cerevisiae是青海传统发酵酸牦牛奶中酵母菌的优势组合。青海海西州采集到的11份酸山羊奶样品中共分离出35株酵母菌。这些菌株经鉴定为Kl. marxianus 16株,P. fermentans 12株、S. cerevisiae 6株和Rh. mucilaginosa 1株。试验结果表明,青海地区酸山羊奶中酵母菌的优势菌为Kl. marxianus(45.7%)和P. fermentans (34.3%)。P. fermentans - S. cerevisiae和Kl. marxianus - S. cerevisiae是青海传统发酵酸山羊奶样品中的酵母菌优势组合。在酸山羊奶样品中没有分离出K. unisporus。更多还原

【Abstract】 The yeast flora of traditional fermented milk products, such as koumiss, kurut and fermented goat milk in Xinjiang and Qinghai of China, were analyzed. The identification and biodiversity of the yeast involved in traditional fermented milk products were investigated. It forms an essential step towards the preservation and exploitation of the hidden potential of the wealth of yeast biodiversity. The results also provide the basic data for systematically understanding the characteristics of koumiss, kurut and fermented goat milk, give useful information for further utilization of yeast in traditional fermented milk products.The counts of yeast in koumiss samples collected from Xinjiang were ranged from 3.12×104 CFU/mL to 2.23×106 CFU/mL. Generally, in koumiss samples, the counts of the yeasts were lower than those of lactic acid bacteria by one or two logarithm. A total of eighty-seven yeast strains were isolated from twenty-eight home-made koumiss samples. They were identified using standard conventional identification methods. And the results were combined with analysis of the large-subunit (26S) rDNA gene D1/D2 domain region sequences of them. The predominant strains proved to be mainly Kazachstania unisporus (49.4% of the total isolates) and Kluyveromyces marxianus (26.4%). Others were identified as Saccharomyces cerevisiae for eight strains, Pichia membranaefaciens for two strains, Pichia fermentans for six strains, Pichia manshurica (synonym Pichia galeiformis)for two strains and Pichia kudriavzevii (synonym Issatchenkia orientalis)for three strains. The combination of K. unisporus and Kl. marxianus was predominant group in koumiss samples in Xinjiang. And the strains of S. cerevisiae and Pichia sp. were never present alone.Variation on the lengths of the ribosomal ITS region (ITS1, 5.8S rRNA and ITS2) of the different yeast strains in koumiss was observed. Three isolates and a type yeast strain were selected for analysis of ITS region sequences. The results confirmed that the ITS region sequencing was a reliable and useful method for yeast taxology.The counts of yeast in kurut samples collected from Qinghai were ranged from 2.60×106 CFU/mL to 2.00×109 CFU/mL. They were lower than those of lactic acid bacteria by one or two logarithm in the samples of Haibei, but were slightly more than those of lactic acid bacteria in the samples of Hainan. A total of seventy-four yeast strains were isolated from twenty-five samples. The predominant strains proved to be mainly P. fermentans (43.2%), S. cerevisiae(27.0%) and Kl. marxianus (24.3%). Others were identified as K. unisporus for one strain, P. kudriavzevii for one strain, Rhodotorula mucilaginosa for one strain and Candida zeylanoides for two strains. P. fermentans - Kl. marxianus, P. fermentans - S. cerevisiae and Kl. marxianus - S. cerevisiae were the predominant groups in kurut samples collected from Qinghai.The counts of yeast in fermented goat milk samples collected from Qinghai were ranged from 2.07×105 CFU/mL to 1.63×108 CFU/mL. They were lower than those of lactic acid bacteria by two or three logarithm in the same sample. A total of thirty-five yeast strains were isolated from eleven samples. The predominant strains proved to be mainly Kl. marxianus (45.7%) and P. fermentans (34.3%). Others were identified as S. cerevisiae for six strains and Rh. mucilaginosa for one strain. Kl. marxianus - S. cerevisiae and P. fermentans - S. cerevisiae were the predominant groups in fermented goat milk samples collected from Qinghai.更多还原