| This article took the Lactobacillus plantarum LIP-1 as the research object,based on the MRS medium,investigated the impact on the number of high cell density cultivation along with survival rate of freeze-drying of Lactobacillus plantarum LIP-1 by changing the composition and content of the medium,and optimized the optimum medium by number of high cell density cultivation and survival rate of freeze-drying.On this basis,in order to analyse the mechanisms of action of how diverse culture medium effects the resistance of LIP-1 after freezing mechanism,selected the fermentation bacteria with similar amount,while the survival rate of Lactobacillus plantarum LIP-1 after freeze-drying is significant differences to analyze proteomics in comparison.The result of single factor and response surface showed that the contents of culture medium had a significant effect on the freeze drying activity of Lactobacillus plantarum LIP-1.The optimal of growth medium of Lactobacillus plantarum LIP-1 was as follows: sucrose 33.35 g/L,multriple nitrogen?soy peptone/yeast powder/ casein peptone was 3:3:5?10.80 g/L,dipotassium hydrogen phosphate/sodium acetate/citrate soidium?1:2.5:1?14.85 g/L,MgSO4 0.2 g/L,MnSO4 0.12 g/L,L-cys 50 mg/L and VB1 40 mg/L.After cultivated in this optimized medium,the amount of fermentation bacteria of Lactobacillus plantarum LIP-1 was 9.892 log CFU/m L and the survival rate after freeze-drying was 77.94%,which were significantly higher than that obtained in standard MRS medium?p<0.05?.On this basis,the proteomics results of significant differences on survival rate of Lactobacillus plantarum LIP-1 after freeze-drying showed that,compared with the control group whose survival rate of freeze-drying was lower,there were 145 different proteins,99 of which were up-regulated and 46 were down-regulated.GO enrichment analysis of differentially expressed protein revealed that,the metabolism and biological regulation related GO terms were enriched and overrepresented in the optimized medium of Lactobacillus plantarum LIP-1.KEGG pathway enrichment analysis revealed that purine metabolism related KEGG term was the most enriched in up-regulated expression,followed by fatty acid synthesis and metabolic pathways.These results indicated that culture medium had a significant effect on the freeze drying activity and the optimized culture medium not only improved the number of high cell density cultivation but also the survival rate of freeze-drying of Lactobacillus plantarum LIP-1.The intrinsic reason of medium composition improved the survival rate of freeze-drying by proteomics analysis was showed that the optimization of culture medium could improve fluidity of the cell membrane,stimulate the growth of Lactobacillus plantarum LIP-1 and then enhance its anti-freeze drying performance,through improving purine metabolism,increasing the expression of cold shock protein csp C and affecting the protein synthesis of cell membrane fatty acids.Therefore,this study provides an important scientific basis for the anti-freeze drying of lactic acid bacteria and lays a theoretical foundation for promoting the industrial production of probiotics. |
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