红薯酒精发酵菌种的选育及液体发酵工艺研究

【作者】 张怀东；

【导师】 刘作易；

【作者基本信息】 贵州大学 ， 微生物学， 2009， 硕士

【摘要】 本研究采用含高浓度酒精培养基从自然界中分离到63株酵母,经四级筛选,最终获得一株适宜以红薯淀粉为原料,在高温条件下进行生料高浓度发酵的高产酒精酵母菌株,编号为Cor-01。该菌株在料水比为1：2.0,装液量30%(v/v),30℃,100 rpm条件下发酵72 h,发酵醪酒精浓度为12%(v/v)。经鉴定Cor-01菌株属于酿酒酵母属(Saccharomyces)的酿酒酵母(Saccharomyces cerevisiae)。为筛选高耐性高产酒精酵母菌株,以Cor-01菌株为出发菌株,进行60Co-γ射线诱变育种。经四级筛选,最终获得一株高耐性高产酒精酵母菌株Cor-01-M2,遗传稳定性良好。该菌株在料水比为1：2.0,装液量30%(v/v),30℃,100rpm条件下发酵60 h,发酵醪酒精浓度为13%(v/v)。本文系统地研究了Cor-01-M2菌株生料发酵红薯淀粉过程中的各种影响因素,如添加氮源、pH、发酵温度、无机离子(硫、磷、钾、锌、镁、钙、钠、铁、铜、锰、铝)、种子培养时间、接种量、摇床转速、惰性载体等。研究了Cor-01-M2以红薯淀粉为原料的生料发酵条件,并用Plackett-Burman设计和Box-Behenken响应面分析进行了优化,得到Cor-01-M2的最优化条件如下：装液量30%(v/v),料水比为1：2.0,α-淀粉酶添加量为30 U/g,糖化酶添加量为240 U/g,接种量10%(v/v),pH 5.2,摇床转速100 rpm,35℃保温发酵,发酵周期60 h。在所获得的最优发酵条件下,菌株Cor-01-M2的发酵醪酒精浓度达14.5%(v/v)、淀粉出酒率达47.75%,淀粉利用率达84.10%。比初始工艺条件下分别提高了11.54%,比出发菌株分别提高了20.83%。更多还原

【Abstract】 63 isolates out of different environments for fuel ethanol-producing yeast were screened by the culture medium which contained high concentration alcohol.By four grades screening, the alcohol high-producing yeast strain Cor-01 was obtained, which was able to use raw sweet potato starch as fermentation substate to produce alcohol in high temperature. The ethanol concentration of fermenting mash could reach 12%(v/v) with the fermentation condition as follow:the ratio of material to water was 1:2.0,72 h,30℃, 100rpm, and 30%(v/v), respectively. The yeast strain Cor-01 was identified as Saccharomyces cerevisiae.To select high level resistance and high yield alcohol yeasts, the start yeast strain Cor-01 was treated with 60Co-y ray. Through four grades screening, the yeast strain Cor01-M2 was obtained, and the genetic stability of the strain was stable. The ethanol concentration of fermenting mash could reach 13%(v/v) with the fermentation condition as follow:the ratio of material to water was 1:2.0,60 h,30℃,100 rpm, and 30%(v/v), respectively.Various influencing factors in the process of the yeast strain Cor-01-M2 fermentation with raw sweet potato starch was studied systematically. Such as nitrogen adding, pH, fermentation temperature, inorganism iron(S, P, K, Zn, Mg, Ca, Na, Fe, Cu, Mn, Al), seed inoculation time, inoculationamount, rotation speed, inert carrier and so on. In addition, the fermentation conditions of the yeast strain Cor-01-M2 was studied. Plackett-Burman and Response Surface Analysis(RSA) methods were applied to optimize fermentation conditions, and The optimal fermentation condition was obtained as follow:the ratio of material to water was 1:2.0, a-Amylase was added as 30 U/g, glucoamylase was added as 240 U/g, inoculation amount was 10%(v/v), pH 5.2, 100rpm,35℃,60 h, and 30%(v/v), respectively. And the ethanol concentration of fermenting mash can reach 14.5%(v/v), the ethanol yield of starch can reach 43.5%, and Starch utilization ratio can reach 84.10%, respectively increased 11.54% in comparison with the original fermentation conditions, and respectively increased 20.83% in comparison with the start yeast strain Cor-01.更多还原