乳酸菌和酵母菌混合培养条件优化研究.doc

乳酸菌和酵母菌混合培养条件优化研究 摘要:对乳酸链球菌和酿酒酵母菌进行混合培养发酵，通过讨论溶氧、温度、pll值、接种最、 接种比例和培养基对其发酵结束时活菌数的影响，确定两种菌在前期28°C摇床150r/min培 养24h,后期37°C静置24h,初始pH为7. 5,接种量为0. 5%,接种比例乳酸菌：酵母菌为 1% : 0. 5%,培养基为YEPD时，两者的活菌数水平达到最高值,乳酸菌达5. OX 108CFU/mL, 酵母菌达 1. OX 108CFU/mLo 关键词:混合培养；酵母菌；乳酸菌 Study on Optimization of Mixed Culture Conditions for Lactic Acid Bacteria and Yeast Abstract: Lactococcus lactis and Saccharomvces cerevisiae were cultivated and fermented together, and the impacts of dissolved oxygen, temperature, pH value, inoculum size, inoculation proportion, and culture medium on the number of viable count at the end of their fermentation were investigatcd. The optimized mixed culture conditions for these two bacteria were obtained as follows: culture for 24 hours in shaker at 150 r / min at 28 °C in earlier period, stewing for 24 hours at 37 °C in later period, the initial pH value was 7. 5, the inoculum size was 0? 5% , the inoculation ratio of lactic acid bacteria to yeast was 1% ： 0. 5% , and the culture medium was YEPD. Un der these conditions, the number of viable count of lac tic aci cl bacteria and yeast reached the highest value, being 5. 0X10 8 and 1? 0 X 10 8 CFU / mL respectively. Key words: Mixed culture; Yeast; Lactic acid bacteria 乳酸菌和酵母菌对人类来说，是非常有益的微生 物菌种，人类在很早的时候就从大白然的变化屮学到 了利用酵母菌进行酿酒、发面、制曲等T艺，利用乳酸 菌制作风味乳制品等。在现代化工艺生产屮，越来越 多的用到了两种菌进行发酵，例如发酵豆粕、微生态制 剂等。但是对于两者混合培养发酵的报道还不是很 多，两者Z间如果能够混合培养而且活菌数水平并不 下降的情况下，可以大大节约发酵能源消耗。本文通 过对2种菌混合培养条件的讨论，旨在为大规模生产 乳酸菌和酵母菌提供理论基础。 1材料与方法 1材料 1. 1菌种 乳酸链球菌(Streptococcus lactis)、酿酒 酵母菌(Saccharomvces cerevisiae)均为河南微生物饲料 研究屮心保藏。 1. 1. 2培养基MRS液体培养基：胰蛋白月东1%、酵 母浸粉0. 5%、匍萄糖2%、牛肉蛋白豚1%、吐温一 80 1%、K 2 HP0 4 0. 2%、结晶乙酸钠0. 5%、柠檬酸三镀 0. 2% 、 MgSO 4 ?7H 2 0 0. 02% 、 MnSO 4 ?411 2 0 0. 005% , pH值6. 8,用于制备乳酸菌种子液；YEPD培养基：胰 蛋白脓2%、酵母浸粉1%、窗萄糖2%,用于制备酵母 菌种了液；乳酸优化培养基：酵母浸粉1%、葡萄糖 0. 5%、结晶乙酸钠0. 5%、柠檬酸三钱0. 2%、吐温一 80 1%、K 2 IIP0 4 0. 2% ,用于混合培养时降低培养基成木； 酵母优化培养基：豆粕粉3%.玉米粉2%、隸皮1%、葡 萄糖3%,用于混合培养时降低培养基成木。以上培养 基均在121 °C下灭菌20 mine 1. 1. 3主要仪器设备立式高压灭菌锅、电子天平、 显微镜、超净-T.作台、怛温摇床、温培养箱、p H计、1 吨立式发酵罐