Study On High Cell Density Cultivation Of Lactobacillus Acidophilus IMAUFB058

In this paper, Lactobacillus acidophilus IMAUFB058, a potential probiotic lactic bacteria,was choosen as the research object, optimization of medium and culture condition were studied to complete the high cell density culture of L. acidophilus IMAUFB058. The main research conclusions are as follows:(1) In order to increase the viable bacteria counts of L. acidophilus IMAUFB058, this study based on the culture medium MRS, all ingredients include the carbon sources, nitrogen sources, total carbon and nitrogen and carbon-nitrogen ratio, buffer salts, trace elements and growth factors were screened and their concentration was adjusted, then using the response surface design to optimize the composition proportion, and through studying the influence of natural extracts on L. acidophilus IMAUFB058growth, forming the optimal medium of L. acidophilus IMAUFB058:sucrose23.24g/L, lactose sugar11.62g/L, low poly fructose11.62g/L, yeast powder8.33g/L, beef extract8.33g/L, casein peptone6.67g/L,. citrate sodium3.62g/L, sodium acetate9.06g/L, K2HPO43.62g/L, MgSO40.2g/L, MnSO40.02g/L, Tween-801.Og/L, L-cysteine hydrochloride0.03g/L, phenylalanine0.Olg/L, carrot juice5%. When cultivated in the optimum medium at37℃for13h, the viable count of fermented broth can get to1.28×109CFU/mL, which was7.19times as many as before (1.78×108CFU/mL).(2) Optimal culture condition was obtained by single factor test: temperature37℃, initial pH6.2, inoculation amount6%.(3) When cultivated L. acidophilus IMAUFB058in the liquid fermentor with the optimum medium, conditions of high cell density fermentation were optimized. Neutralizing agent, pH, stirring speed and ventilation were the main influence factors of high density fermentation process optimization. Result showed the optimum fermented condition was:culture temperature37℃, inoculation amount6%, neutralizing agent10M NaOH, pH5.8(initial pH6.2), revolution speed150rpm, added nitrogen.With the best high density fermentation conditions of L.acidophilus IMAUFB058, the cultivation time was11h which was lower than before for at least2h, and the viable count of L. acidophilus IMAUFB058can reach5.28×109CFU/mL, which increased29.67 times than before.