降胆固醇嗜酸乳杆菌的诱变选育

通过诱变获得具有降胆固醇功能的优良嗜酸乳杆菌新菌株。利用亚硝基胍(作用浓度为1 g/L)对嗜酸乳杆菌进行诱变。突变菌株测定其耐渗透压和抗胆盐能力后,在含有0.3 g/L胆固醇的培养基中培养48 h,测定降胆固醇率。挑选优良突变菌株制成酸奶并喂养高脂大鼠模型,28 d后测定血清及粪便胆固醇指标。嗜酸乳杆菌突变后获得的60个突变菌株中有8株具有良好的耐渗透压和抗胆盐能力,其中突变株Y48的清除胆固醇能力最高,清除率达到(61.44±1.8)%。Y48发酵酸奶喂养高脂大鼠模型28 d后与对照大鼠模型相比,血清中TC、TG明显减少(P<0.05),粪便TC明显增加。通过诱变获得了优良的嗜酸乳杆菌突变菌株,为今后获得优质降胆固醇乳酸制品提供良好的候选菌种。

Mutation Breeding of Cholesterol-Reducing Lactobacillus acidophilus

A cholesterol-reducing fine Lactobacillus acidophilus new strain through mutation was obtained. 1μ/L of NTG was used to mutate L. acidophilus. After the mutant was tested for its osmotic-pressure resistance and its anti- cholate ability, it was cultured in medium containing 0.3 g/L for 48 h to examine for its cholesterol-reducing rate. Yo- gurt fermented by the selected fine mutant was fed artificially-induced hyperlipemia SD rats models and cholesterol in their serum and feces were determined 28 day＇ s after the feeding. The results showed there were 8 strains among 60 mutants possessed fine osmotic-pressure resistance and anti-cholate ability, mutant strains Y48 was the highest in abil- ity to eliminate cholesterol, the eliminating rate was as high as （61.44 ± 1.80 ）%. 28 days after the Y48 strain fermented yogurt to feed hyperlipemia SD rats the level of TC and TG （ P 〈 0. 05 ） in serum noticeably reduced, and TC in their feces significantly increased. Therefore, fine L. acidophilus mutant strain was successfully obtained, and pro- vided fine candidate strains to get high-grade cholesterol-reducing dairy in the future.