重离子束辐照诱变选育嗜酸乳杆菌及微胶囊制备和稳定性研究

Mutation Breeding of Lactobacillus acidophilus by Heavy Ion-Beam Irradiation and Preparation and Stability of Microcapsules

为提高嗜酸乳杆菌在饲料中的应用范围,采用重离子束12C6+在不同辐照剂量(0、25、50、75、100、125、150、175 Gy)下对嗜酸乳杆菌4017(La 4017)进行辐照诱变,确定最优辐照剂量;在最优辐照剂量筛选突变株,采用不同壁材(海藻酸钠、海藻酸钠+明胶、海藻酸钠+聚丙烯酰胺、海藻酸钠+壳聚糖、海藻酸钠+聚乙烯醇、海藻酸钠+聚乙烯醇+活性炭)制备微胶囊并研究微胶囊的稳定性。结果表明:在辐照剂量为100 Gy时,通过筛选获得遗传稳定的突变株La 4017-d1,44℃连续传代5次,存活率达到92.3%,较原始菌株提高了40%;采用海藻酸钠+聚乙烯醇包埋突变株La 4017-d1制备得到的微胶囊,包埋率达到82.67%,在模拟胃液中3 h后的存活率达到68.02%,在模拟肠液中1.5 h后的释放率达到96.04%。综上可知,重离子束辐照得到的嗜酸乳杆菌突变株La 4017-d1的耐胆盐及耐高温稳定性较好;经海藻酸钠+聚乙烯醇包埋该突变株获得的微胶囊,能够抵御胃液强酸环境,并在肠道中定植释放活菌。

In order to improve the application of Lactobacillus acidophilus in feed,the Lactobacillus acidophilus 4017(La 4017)was irradiated by using heavy ion-beam12C6+at different doses(0,25,50,75,100,125,150 and 175 Gy),and the optimal irradiation dose was determined. The mutant strain was screened at the optimal irradiation dose,the microcapsules were prepared by different wall materials(sodium alginate,sodium alginate+gelatin,sodium alginate+polyacrylamide,sodium alginate+chitosan,sodium alginate+polyvinyl alcohol,sodium alginate+polyvinyl alcohol+activated carbon),and the stability was studied. The results showed that the mutant strain La 4017-d1 was screened at irradiation dose of 100 Gy,the survival rate was 92.3% after5 generations at 44 ℃ and increased by 40% compared with the original strain. The microcapsules prepared by embedding strain La 4017-d1 with sodium alginate+polyvinyl alcohol which embedding rate was 82.67%,the survival rate was 68.02% in simulated gastric juice after 3 h and the release rate was 96.04% in simulated intestinal juice after 1.5 h. In summary,the mutant strain La 4017-d1 obtained by heavy ion irradiation has good bile salts and high temperature tolerance. The microcapsules prepared by embedding mutant strain La 4017-d1with sodium alginate+polyvinyl alcohol can resist the strong acid environment in gastric juice and release live bacteria in the intestinal tract.[Chinese Journal of Animal Nutrition,2023,35(1):652-661]