Karki Tika B, Timilsina Parash Mani, Yadav Archana, Pandey Gyanu Raj, Joshi Yogesh, Bhujel Sahansila, Adhikari Rojina, Neupane Katyayanee
Department of Biotechnology, Kathmandu University, Dhulikhel, Nepal.
Biotechnological Research and Development Center Pvt., Ltd., Bharatpur, Nepal.
Biotechnol Res Int. 2017;2017:1925820. doi: 10.1155/2017/1925820. Epub 2017 Dec 13.
The study aims to isolate the yeast strains that could be used effectively as baker's yeast and compare them with the commercial baker's yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree "Dar" were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wallerstein Laboratory Nutrient Agar. From the differential tests which included morphological and microscopic observation and physiological and biochemical characterization such as nitrate reduction and lactose utilization tests, 8 strains were selected as possible strain. The selected strains were further assessed for their efficient leavening ability by tests such as ethanol tolerance, osmotolerance, invertase test, and stress exclusion test. The three most potent strains ENG, MUR3B, and SUG1 isolated from grape, Murcha, and sugarcane, respectively, were used in the fermentation and baking of dough. These strains also carried a possibility of being used as industrial baker's yeast.
该研究旨在分离出可有效用作面包酵母的酵母菌株，并将它们与尼泊尔市场上现有的商业面包酵母进行比较。分别从尼泊尔巴克塔普尔、卡夫雷和锡扬贾县的不同地点收集了总共10个样本，包括水果、穆尔查以及当地树木“达尔”等本地可获取的来源。在对样本进行富集和发酵后，使用选择性培养基沃勒斯坦实验室营养琼脂分离出了26株酵母菌株。通过包括形态学和显微镜观察以及生理生化特性（如硝酸盐还原和乳糖利用测试）在内的鉴别试验，选择了8株菌株作为可能的菌株。通过乙醇耐受性、渗透压耐受性、转化酶测试和应激排除测试等试验，进一步评估所选菌株的有效发酵能力。分别从葡萄、穆尔查和甘蔗中分离出的三株最具潜力的菌株ENG、MUR3B和SUG1被用于面团的发酵和烘焙。这些菌株也有可能被用作工业面包酵母。
