Isolation, Identification And Cultures Of The Microbial Strains From The Chinese-style Dry Fermented Sausage

It is more than 2,000 years since the fermented sausage were first made in China. However, it is only a few decades since the metabolism of starter was used in the production of the fermented sausage. However, China, mainly studying on the selection of the microbial starter and the changes of the biochemical and physiological indexes at the laboratory stage, has a long way from the big industrialized production. Isolation and identification of the fermentative microbiology from YanTai Siver dry fermented sausage have been carried out in this study. And the cultures of the valuable microbial strains have been studied. The main results are as follows:1,Isolation and identification of the strains(1) 81 strains of lactic acid bacteria and 33 strains of cocci were isolated and purified in the MRS agar and MSA agar from YanTai Siver dry fermented sausage. Then, 8 strains of lactic acid bacteria with excellent fermentative features were selected on the base of the dry fermented sausage. They could resist 6% Nacl and 150 mg/kg nitrite, and they did not produce CO2 from glucose, H2S, NH3 from arginine, H2O2. and slime, nor did they have decarboxylase activity. Acidificaction rate and acidifying capacity of them were better than other strains. In addition, E.coli and S. aureus were inhibited by them. And 4 strains of cocci were selected. They displayed nitrate reduction, catalase-positive, proteinase and lipase activity besides some characteristic of the secleted lactic acid bacteria.(2) The seclected strains were identified using standard conventional identification methods. 5 strains of lactic acid bacteria, 3 strains of Pediococcus, 3 strains of Staphylococcus, and 1 strain of micrococcus were obtained.2,The culture of the secleted strainsThe promoting medium of 8 strains of lactic acid bacteria and 4 strains of cocci were respectively optimized by the uniform design. The optimum nutrient factors were determined.(1) There were more living-cells of lactic acid bacteria and cocci in the enrichment medium than in the MRS and MSA medium culturing for 24 hours at 30℃. Of Lactobacillus, L3 grew the best in the enrichment medium. The number of living bacteria of L3 cultivated in the optimum enrichment medium for 24 hours at 30℃was 1.4×1011 cfu/ml, an increase of 146.4 times in the viable counts of bacteria than in the MRS medium. Of Pediococcus, P1 grew the best in the enrichment medium. The number of living bacteria of P1 cultivated in the optimum enrichment medium was 9.4×1010 cfu/ml, an increase of 183.3 times in the viable counts of bacteria than in the MRS medium. Of cocci, Q1 grew the best in the enrichment medium. The number of living bacteria of Q1 cultivated in the optimum enrichment medium was 2.8×1010 cfu/ml, an increase of 34.9 times in the viable counts of bacteria than in the MSA medium.(2) The results of the mixed-culture were as follows: the optimum proportions of the mixed-culture of Lactobacillus, Pediococcus and cocci were L1:L2:L3:L4:L5=1:1:1:1:1, P1:P2:P3=1:2:1, Q1:Q2:Q3:Q4=1:2:1:1.