三株甘蔗糖蜜酒精发酵高产酵母菌株的筛选

Screening Three High-yield Saccharomyces cerevisiae Strains for Alcohol Fermentation of Sugarcane Molasses

关键词:  酵母菌株  筛选  酒精  糖蜜

Key words:  Saccharomyces cerevisiae strain  screening  alcohol  molasses

摘要:

从甘蔗糖厂的废弃物中筛选到3株甘蔗糖蜜酒精发酵高产菌株MF1001、MF1002和MF1003,经rDNA ITS序列同源比对鉴定为酿酒酵母(Saccharomyces cerevisiae)的不同菌株。3个菌株均可以完全利用葡萄糖和蔗糖,部分利用棉子糖和半乳糖,均不能利用乳糖和木糖。MF1001发酵甘蔗糖蜜的残糖含量明显低于目前使用的生产菌株,略低于标准测定菌株CICC31149和CICC31279,MF1002和MF1003的残糖含量略低于目前使用的生产菌株。与生产菌株相比,3个菌株在甘蔗糖蜜的生长速率略低,但是维持高菌数的时间较长。按目前甘蔗糖蜜酒精生产的发酵工艺,3个菌株30℃发酵72h的醪液酒精含量分别为14.26%(V/V)、14.48%(V/V)和13.50%(V/V),比目前生产使用的菌株高19.5%~28.6%;37℃发酵40h的醪液酒精含量分别为12.03%(V/V)、12.06%(V/V)和12.14%(V/V),比目前生产使用的菌株高10.0%~11.7%。这3个菌株具有提高甘蔗糖蜜发酵醪液酒精含量的潜在工业价值。

Abstract:

Three high-yield strains, MF1001, MF1002 and MF1003, for alcoholic fermentation of sugarcane molasses, were screened from years old wastes of sugar mill.By aligning ITS sequences using the program Blast with GenBank databases, the strains were identified belong to different strains of Saccharomyces cerevisiae.All screened strains can completely utilize glucose and sucrose, partly utilize raffinose and galactose, but cannot utilize lactose and xylose for metabolism.The un-fermentable residual sugar of MF1001 fermenting sugarcane molasses was significant lower than that of two control strains used currently for industrial alcohol fermentation with sugarcane molasses as substrate, and a little lower than that of standard strains currently used for determining un-fermentable sugar of sugarcane molasses.The un-fermentable residual sugar of MF1002 and MF1003 fermenting sugarcane molasses was a little lower comparing with industrial strains.The growth rate of screened strains in 20°Bx sugarcane molasses was slower than that of industrial strains, but they maintained a large cell number for a longer period.By using the industrial process for alcohol fermentation of sugarcane molasses, the alcohol concentration in broth of fermenting sugarcane molasses by screened strains at 30℃ for 72h was 14.26% (V/V), 14.48% (V/V) and 13.5% (V/V) for MF1001, MF1002 and MF1003, respectively, 19.5%~28.6% higher than that of industrial strains (11.30% and 11.26%).Even under 37℃, the alcohol concentration of broth after fermentation for 40h by screened strains was 12.03% (V/V)、12.06% (V/V)和 12.14% (V/V), respectively, still 10.0%~11.7% higher than that of industrial strains (10.93% and 10.87%).The results indicated that the screened strains are much potential for industrial utilization to enhance the alcohol concentration of sugarcane molasses fermentation.