Studies On The Breeding Of Efficient Blood Fattiness-degrading Bacterium And Their Characters

This paper researched on the breeding of efficient blood fattiness-degrading bacterium and characters of mutants. The main results were as follows:1. With the high tolerance of bile salts and acid, efficient cholesterol-degrading strain SL1 and efficient triglyceride-degrading strain BC1 were screened from samples and were identified as Lactobacillus acidophilus and Bacillus cereus separately. SL1-5 and BC1-6 strains with steady transmissibility were screened from mutants, the degradation rate of cholesterol after 48 h incubation with SL1-5strain was up to 82.9%, increased by 16.1%. The degradation rate of triglyceride after 48 h incubation with BC1-6 strain was up to 64.6%, increased by 36.5%. Both SL1-5 and BC1-6 strains could inhibit the growth of E.coli and S.aureu.2. The optimum growth medium of SL1-5 strain were peptone 12.5 g, beef extract 12.5 g, yeast extract 6 g, (NH₎2HC₆H₅O₇ 2 g, glucose 25 g, K₂HPO₄ 2 g, CH₃COONa 5 g, MgSO₄·7H₂O 0.58 g, MnSO₄·H₂O 0.25 g, tween-80 1 mL. Its optimum growth conditions were.pH 5.5, 39℃. Its optimum ferment medium were peptone 12.5 g, beef extract 12.5 g, yeast extract 6 g, (NH₄)₂HC₆H₅O₇ 3g, glucose 20 g, K₂HPO₄ 2 g, CH₃COONa 5 g, MgSO₄·TH₂O 0.86 g, FeSO₄·7H₂O 0.83 g, MnSO₄·H₂O 0.25 g, cholesterol 0.8 g, tween-80 0.5 mL.3. The optimum growth medium of BC1-6 strain were tryptone 18 g, yeast extract 10 g, NaCl 5 g, glucose 6 g. The optimum ferment medium were tryptone 15 g, yeast extract 7.5 g, NaCl 5 g, FeSO₄·7H₂O 1.4 g and triglyceride 10 mL. And its optimum growth and ferment conditions were pH 6.5, 37℃and 160 r/min.4. The enzyme of SL1-5 strain and BC1-6 strain was mostly distributed outside the cells. During the degrading process, cholesterol was absorbed by SL1-5 strain, which differed from BC1-6 strain.5. SL1-5 strain and BC1-6 strain were proved to be safety by toxicity test. The two strains all had effect on hyperlipemia mice model, which was induced by feeding mice with high-fat food for 16 days. Mice fed both SL1-5 and BC1-6 strains had 35.5% lower serum cholesterol and 14.2% lower serum triglycerides compared to the control mice. The results showed that the two strains had better degrading.