Study On High Cell Density Culture Of Lactobacillus Fermentrum IMAU 10129

High cell density culture is one of the most important link in the agent preparation of starter culture,which plays an important theoretical and practical role in the development and application of fermentated products.In this paper,we mainly studied on Lactobacillus fermentum IMAU 10129,a potential probiotic strain,which was originally isolated from traditional dairy products of herdsmen.to increase the number of viable bacteria,we studied on optimization and analysis of medium,static culture and high cell density cultitation technique,which could lay the foundation for its application in microecological preparations of different fields.On the basis of MRS medium,single factor test,orthogonal test and response surface analysis were adopted.Optimal mediun of L.fermentum IMAU 10129 were determined as follow,70.00 g/L sucrose,35.66 g/L fish peptone,11.89 g/L yeast powder,6.44 g/L C6H5NaO7·2H2O,1.80 g/L CH3COONa,4.98 g/L K2HP04,0.10 g/L MnSO4·5H2O,1.00 g/L MgSO4·7H2O,0.03 g/L uracil,0.60 g/L potato extract,1.00 g/L Tween-80.Cultivated in the above medium for initial pH 7.0,inoculation amount 5.21×107CFU/mL and 37? thermostatic incubation.The living cells of L.fermentum IMAU 10129 were incresed to 4.21 x 109 CFU/mL,which were nearly 5 times higher than that in the unimproved MRS medium(8.70 x 108 CFU/mL).According to the growth curves of L.fermentum IMAU 10129 cultured in MRS medium and optimised medium,the latter approved longer exponential growth phase duration,higher cell density and the lower pH value of end-point fermentation.On the basis of optimal medium and static,the optimal culture conditions of high cell density cultivation were obtained:initial pH 7,37 ? anaerobic incubation of mixed gas;The pH value was constant at 5.5 by adding 25%of sodium carbonate.Under this condition,the living cells of L.fermentum IMAU 10129 were raised to 8.50×109 CFU/mL,and had doubled that in static state(4.21 ×109 CFU/mL).Optimization the medium and high cell density cultivation of L.fermentum IMAU 10129,a low cost technique with high living cells was achieved,which was beneficial to industrial production and application of L.fermentum IMAU 10129 as biologic.