摘要:
为获得适用于高酸果汁发酵的酵母菌,本文从蓝莓和红树莓自然发酵的果汁中,分离筛选出2株在pH2.3、pH4.8时生长良好的酵母菌,经形态学、生理生化及分子生物学鉴定,编号J-23为季也蒙有孢汉逊酵母菌(Hanseniaspora guilliermondii),编号L-6为酿酒酵母菌(Saccharomyces cerevisiae)。在pH2.3、pH4.8酸环境下,以市售果酒酵母菌和葡萄汁有孢汉逊酵母菌为对照菌株,对J-23、L-6酵母菌的耐酸适应性进行研究,利用扫描电子显微镜(SEM)和透射电子显微镜(TEM),分别对细胞膜、细胞壁及胞内结构进行观察,并对酸胁迫中过氧化氢酶(CAT)和超氧化物歧化酶(SOD)的活力进行测定,结果显示:J-23和L-6酵母菌菌体形态无明显的凹陷、褶皱等现象,细胞结构清晰,且液泡变大;当pH2.3时,J-23酵母菌与对照菌1、L-6酵母菌与对照菌2中SOD酶活力分别为790.98、768.71、795.02、772.15 U/mL;CAT酶活力分别为389.81、370.85、385.17、373.31 U/mL。J-23和L-6菌株中2种酶活力均显著高于对照菌株,抗氧化能力增强,使菌株可以更好地适应酸胁迫环境。
Abstract:
In order to obtain yeast suitable for high-acid juice fermentation,two strains of yeast which grew well at pH2.3 were isolated and screened from the naturally fermented juice of blueberry and red raspberry,and their morphology,physiology,biochemistry and molecular biology were studied. Identificated the J-23 was Hanseniasporus guilliermondii,and the L-6 was Saccharomyces cerevisiae. The acid-tolerant adaptability of J-23 and L-6 yeasts were studied in a pH2.3,pH4.8 acid environment using commercially available fruit wine yeast and Hanseniaspora uvarum as control strains. And the cell membrane,cell wall and intracellular structure were observed by SEM and TEM. The activities of catalase(CAT)and superoxide dismutase(SOD)in acid stress were measured. The results showed that the morphology of J-23 and L-6 yeast cells had no obvious depressions,wrinkles and so on,the cell structure was clear,and the vacuole became large. The SOD activity of J-23 yeast and control bacteria 1,L-6 yeast and control bacteria 2 were respectively 790.98,768.71,795.02 and 772.15 U/mL,meanwhile,the CAT enzyme activities were respectively 389.81,370.85,385.17 and 373.31 U/mL at pH2.3. The enzyme activities of both J-23 and L-6 strains were significantly higher than the control strains,which could better adapt to the acid stress environment.
下载:
