【摘要】 耐氧性能不足是双歧杆菌在酸奶产品中添加应用的一个重要问题。本试验对搭载神舟十一号返回式飞船的动物双歧杆菌菌株进行分离纯化并得到10株突变株。以耐氧系数为评价指标对菌株进行筛选,对野生株BB-11与突变株的遗传稳定性、生长曲线、不同氧浓度条件(氧气浓度为0、5%、10%、15%、21%)下菌株的活菌数等指标进行测定,并对菌株的菌落形态及微观形态进行观察。结果表明,10株突变株中有5株耐氧系数显著高于野生菌株(P<0.05),其中有一株突变株耐氧MN-Gup遗传稳定且耐氧系数显著高于野生菌株;耐氧突变株的生长趋势与野生株相似,但是高于野生株。在5%氧气浓度下,耐氧突变株OD600达到1.110±0.02,活菌数最高达到8.46±0.13(log cfu/m L),均高于野生株;形态学观察发现突变株与野生株在表观形态上没有差异。动物双歧杆菌BB-11经过航天诱变后耐氧性能发生改变,突变株动物双歧杆菌MNGup耐氧性能良好且遗传稳定。对BB-11和MN-Gup在p H 2.5(盐酸调节p H)和0.3%的胆盐浓度下进行活菌数检测,结果表明两株菌均具有良好的胃酸和胆盐耐受性,并且两株菌之间无显著差异(P>0.05);B1为坚强肠球菌,B2为海氏肠球菌,B3和B4均为屎肠球菌。本研究为防治犊牛腹泻提供了更多的候选菌种。更多还原

【Abstract】 In this experiment, the aerospace mutants of Bifidobacterium animalis BB-11 with enhanced aeortolerant ability were isolated and purified from the shenzhou-11 re-entry spacecraft. The strains were screened using the oxygen tolerance coefficient as an index. The genetic stability, growth curve, and the viability of the wild strain BB-11 and the mutant strains under different oxygen concentration(Oxygen concentration 0, 5%, 10%, 15%, 21%) were measured. And the colony morphology and microscopic morphology of the strain were observed. The results showed that 5 of the 10 mutant strains had significantly higher oxygen tolerance coefficients than the wild strain(P<0.05). Among them, the MN-Gup had a stable oxygen tolerance and its oxygen tolerance coefficients was consistently significantly higher than the BB-11. The growth curve showed that the growth tendency of the MN-Gup was similar to that of the wild strain. Under the condition with 5% oxygen, the OD600 of aeortolerant mutant MN-Gup OD600 reached 1.110±0.02 and the viable count reached 8.46±0.13(log cfu/m L), which was higher than that of the wild strain BB-11. Scanning electron microscope and morphological observations found no difference in apparent morphology between wild strains and mutant strains. After space mutation, the oxygen tolerance of Bifidobacterium animalis BB-11 has been changed. Acid and bile salt tolerances of strain were tested, the results showed that both BB-11 and MN-Gup with good acid and bile salt tolerance. There was no significant difference between these two strains(P > 0.05).更多还原