Antagonistic activity and protective effect of a Bacillus subtilis isolate against fish pathogen Edwardsiella piscicida
2019
Ren, Xiaomeng | Wu, Binbin | Zhao, Feng | Qi, Lingling | Qiu, Xianfeng | Li, Ran | Yang, Sisi | Liu, Fuguo | Yi, Ganfeng | Ding, Xuezhi | Xia, Liqiu | Sun, Yunjun
Bacillus subtilis ZFB19 isolated from the intestine of healthy grass carp exhibited considerable antagonistic activity against Edwardsiella piscicida which was resistant to various antibiotics. Its extracellular antibacterial substance was stable under wide range of pH, temperature, and proteinases. The active component was purified through HPLC and exhibited molecular weight of 560.28198 as revealed by mass spectrometric analysis. By utilizing adult zebrafish as well as ZF4 cell line, we found that pretreatment of zebrafish and ZF4 cell with B. subtilis ZFB19 could attenuate E. piscicida-induced mortality. The lymphoid tissues (liver, spleen, and kidney) of zebrafish injected with strain ZFB19 showed significant enhancement in the levels of respiratory burst activity, nitric oxide production, lysozyme activity and total protein content. Meanwhile, initial internalized E. piscicida and its intracellular replication in ZF4 cells could be obviously reduced by B. subtilis pretreatment. This study is helpful for understanding the mechanism that underlies the effects of probiotic Bacillus in reducing fish pathogen infection.
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