The Effect of Oral Probiotic Bacillus amyloliquefaciens on Intestinal Microbiota, Intestinal Structure, Serum Antioxidant Capacity and Inflammatory Responses of Heat Stressed Rats.

This study investigated the effect of Bacillus amyloliquefaciens (BaSC06) in alleviating heat stress in rats. The rats were randomly divided into four groups. Each rat in Group 1 and Group 3 received oral 1 ml/day of PBS, whereas those in Group 2 and Group 4 were administered 1 ml/day of BaSC06 (10⁸ CFU/ml). After two weeks, the rats in Groups 3 and 4 were exposed to heat stress at 42°C for 30 min, while those in Groups 1 and 2 were maintained at 25°C. The result showed that oral BaSC06 increased abundance of Firmicutes phylum and Ruminococcaceae Family along with reduced level of Bacteroidetes family. Compared to Group 1, the height of small intestine villi increased significantly (P < 0.05) in Group 2, and intestinal villus height and mucosal thickness decreased significantly in Group 3 than that in Group 4 (P < 0.05). The distribution of ZO-1 was disrupted in Group 3 which was ameliorated in Group 4. The number of bacteria in the liver, spleen and mesenteric lymph nodes was significantly higher in Group 3 than other groups (P < 0.05) meanwhile the LPS level in Group 4 decreased significantly compared to Group 3 (P < 0.05). The levels of IL-1, IL-10 , HSP70 and MDA increased significantly (P < 0.05), the activity of CAT decreased significantly (P < 0.05) in Group 3 compared to the other groups. The adverse effects of heat stress can be alleviated by gavage BaSC06, which improve the composition of intestinal microbiota. It is helpful to elucidate the mechanism of probiotics to counteract the negative effects of heat stress.