AUTHOR=Jiang Zipeng , Li Wentao , Su Weifa , Wen Chaoyue , Gong Tao , Zhang Yu , Wang Yizhen , Jin Mingliang , Lu Zeqing 

TITLE=Protective Effects of Bacillus amyloliquefaciens 40 Against Clostridium perfringens Infection in Mice

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.733591

DOI=10.3389/fnut.2021.733591

ISSN=2296-861X

ABSTRACT=<p>This study aimed to investigate the protective effects of <italic>Bacillus amyloliquefaciens</italic> (BA40) against <italic>Clostridium perfringens</italic> (<italic>C. perfringens</italic>) infection in mice. <italic>Bacillus subtilis</italic> PB6 was utilized as a positive control to compare the protective effects of BA40. In general, a total of 24 5-week-old male C57BL/6 mice were randomly divided into four groups, with six mice each. The BA40 and PB6 groups were orally dosed with resuspension bacteria (1 × 10<sup>9</sup> CFU/ml) once a day, from day 1 to 13, respectively. In the control and infected groups, the mice were orally pre-treated with phosphate-buffered saline (PBS) (200 μl/day). The mice in the infected groups, PB6 + infected group and BA40 + infected group, were orally challenged with <italic>C. perfringens</italic> type A (1 × 10<sup>9</sup> CFU/ml) on day 11, whereas the control group was orally dosed with PBS (200 μl/day). The results showed that the BA40 group ameliorated intestinal structure damage caused by the <italic>C. perfringens</italic> infection. Furthermore, the inflammatory responses detected in the infected groups which include the concentrations of IL-1β, TNF-α, IL-6, and immunoglobulin G (IgG) in the serum and secretory immunoglobulin (SigA) in the colon, and nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) activity in the jejunum, were also alleviated (<italic>P</italic> &lt; 0.05) by BA40 treatment. Similarly, cytokines were also detected by quantitative PCR (qPCR) in the messenger RNA (mRNA) levels, and the results were consistent with the enzyme-linked immunosorbent assay (ELISA) kits. Additionally, in the infected group, the mRNA expression of <italic>Bax</italic> and <italic>p53</italic> was increasing and the <italic>Bcl-2</italic> expression was decreasing, which was reversed by BA40 and PB6 treatment (<italic>P</italic> &lt; 0.05). Moreover, the intestinal microbiota imbalance induced by the <italic>C. perfringens</italic> infection was restored by the BA40 pre-treatment, especially by improving the relative abundance of <italic>Verrucomicrobiota</italic> (<italic>P</italic> &lt; 0.05) and decreasing the relative abundance of <italic>Bacteroidetes</italic> (<italic>P</italic> &lt; 0.05) in the phyla level, and the infected group increased the relative abundance of some pathogens, such as <italic>Bacteroides</italic> and <italic>Staphylococcus</italic> (<italic>P</italic> &lt; 0.05) in the genus level. The gut microbiota alterations in the BA40 group also influenced the metabolic pathways, and the results were also compared. The purine metabolism, 2-oxocarboxylic acid metabolism, and starch and sucrose metabolism were significantly changed (<italic>P</italic> &lt; 0.05). In conclusion, our results demonstrated that BA40 can effectively protect mice from <italic>C. perfringens</italic> infection.</p>