【摘要】 本研究以黄瓜汁为基础培养基,添加2%的葡萄糖、0.5%的蛋白胨等,对5株乳酸菌进行了生长性能和发酵性能研究。优选其中两株菌作为制备发酵剂的菌种,前期研究高密度细胞培养的条件、培养基成分,以培养过程中的pH值、活菌数为指标,后期研究制备发酵剂的最佳离心条件、筛选最适的冻干保护剂及浓度等进行了系统研究,研究表明,在接种量3%,培养温度30℃,初始pH6.6,装液量40mL(100mL三角瓶),振荡频率120r/min条件下培养,培养14h后补充营养物质继续培养,到20h时可使乳酸菌活菌数达到7.24×109cfu/mL。4℃、4000r/min离心30min为收集细胞的最佳条件,以10%的脱脂乳为冻干悬浮基质,对蔗糖、血清蛋白、甘油、海藻酸钠四种保护剂的保护效果进行了研究,结果表明,甘油的保护效果最佳,冻干后菌体的存活率最高,10%的脱脂乳保护效果次之。该研究旨在为直投式的乳酸菌发酵剂用于工业化发酵生产橄榄菜提供理论依据。更多还原

【Abstract】 A primary medium which was on the basis of cucumber juice was prepared by adding 2% glucose, 0.5% peptone. The fermentative ability of five lactic acid bacteria was studied, which affirmed two strains was the primary fermentative species. Taking pH value and living cell count as indexes in the process of fermentation,the experiment had studied strain ratios, cultural medium components, cultivation conditions, enrichment methods and cryoprotectant. The results indicated that seeding volume was 3%, the incubation temperature was 30℃, initial pH was 6.6, cultural fluid amount was 40mL, shaking 120rpm. after 14 hours, nutrient substance was added to the medium and the cell population got to 7.24×109 cfu/mL, after 20 hours’ culture. The optimum centrifugation conditions was 4℃、4000r/min.30minute for getting cell. Using 10% nonfat dried milk as suspended substrate, the function of four protectors including sucrose, serum protein, glycerin and trehalose were studied,results suggested that all of them had some effects on promoting cell count and glycerin was the best one.The purpose was to provide experimental basis for ready-to-use starters.更多还原