Abstract: Using MRS medium,the fermentative ability of five lactic acid bacteria was studied respectively,and two strains were affirmed as the primary fermentative species.Taking pH value and living cell count as indexes in the process of fermentation,the experiment studied strain ratios,cultural medium components,cultivation conditions,enrichment methods and cryoprotectant.The results indicated that the incubate volume 2%,the temperature 30℃,initial pH 6.6,cultural fluid amount 40ml,and shaking frequence 120r/min.After 14 hours,nutrient substance was added to the medium and after 20 hours of the total cells obtained are up to 7.24×109 CFU/ml.The optimum centrifugation conditions are:4℃,4000r/min,30min.Using 10% nonfat milk as suspended substrate,the function of four protectors including sucrose,serum protein,glycerin and trehalose was studied respectively.The results suggested that all of them show some perfective effects on the living cell,while 10% nonfat milk and serum protein are among the best.The purpose of this study is to provide experimental basis for ready-to-use starters.

Key words:  , culture starter； high cell concentration cultivation； cryoprotectant； freeze-drying；