Abstract:

Objective To study the culture conditions of Lactobacillus acidophilus,and to develop a fermentation with high  bacterial activity,big density,simple operation,
easy for  production application,and to clarify the production and application of lactic acid bacteria.   Methods Lactobacillus acidophilus strain of Chinese strai
ns were selected;according to the proportion of different medium components,experimental group and control group were set up;the  culture conditions
 and formula of MRS liquid culture medium were optimized,and the A650 value  of bacteria liquid  and the number of live bacteria were detected by UV spectrophotometer,and    the optimal process was screened out.   Results Through screening  the optimum culture conditions of Lactobacillus acidophilus were determined; the inoculation quantity was 1%,initial pH value was 6.2,the constant temperature was 37 ℃ and the culture time was  23 h..The optimum culture medium formula was peptone 3.5%,yeast extract 0.5%,2% glucose,0.2% citric acid ammonium,0.088% sodium hydrogen phosphate two,0.6% sodium acetate,0.025% manganese sulfate,magnesium sulfate 0.06%,1% nutrition factor,0.1% Twain 80;the  number　of bacteria  was  up to 1.43 × 10¹¹ cfu.mL^-1 cultured with the optimal culture process;compared with the traditional training scheme,the number of  bacteria species was increased  about 1×10¹¹ cfu.mL^-1,and the process was simple and easy.   Conclusion Through the optimization of   culture conditions and  culture medium of Lactobacillus acidophilus,the best culture conditions of Lactobacillus acidophilus are obtained,the high density cultivation of strain is conduted,and  a theoretical foundation for   preparation and application of lactic acid bacteria is laid.

Key words: Lactobacillus acidophilus, high density, culture condition, optimization, process