Probiotic potential of Bacillus velezensis JW: Antimicrobial activity against fish pathogenic bacteria and immune enhancement effects on Carassius auratus

Yanglei Yi; Zhenhua Zhang; Fan Zhao; Huan Liu; Lijun Yu; Jiwei Zha; Gaoxue Wang

doi:10.1016/j.fsi.2018.04.055

Probiotic potential of Bacillus velezensis JW: Antimicrobial activity against fish pathogenic bacteria and immune enhancement effects on Carassius auratus

Fish Shellfish Immunol. 2018 Jul:78:322-330. doi: 10.1016/j.fsi.2018.04.055. Epub 2018 Apr 25.

Authors

Yanglei Yi¹, Zhenhua Zhang², Fan Zhao³, Huan Liu³, Lijun Yu³, Jiwei Zha⁴, Gaoxue Wang⁵

Affiliations

¹ College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China; Molecular Genetics, University of Groningen, Groningen, The Netherlands.
² Molecular Genetics, University of Groningen, Groningen, The Netherlands.
³ College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China.
⁴ College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
⁵ College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China. Electronic address: wanggaoxue@126.com.

PMID: 29702236
DOI: 10.1016/j.fsi.2018.04.055

Abstract

This study evaluated the probiotic potential of B. velezensis JW through experimental and genomic analysis approaches. Strain JW showed antimicrobial activity against a broad range of fish pathogenic bacteria including Aeromonas hydrophila, Aeromonas salmonicida, Lactococcus garvieae, Streptococcus agalactiae, and Vibrio Parahemolyticus. Fish (Carassius auratus) were fed with the diets containing 0 (control), 10⁷, and 10⁹ cfu/g of B. velezensis JW for 4 weeks. Various immune parameters were examined at 1, 2, 3, and 4 weeks of post-feeding. Results showed that JW supplemented diets significantly increased acid phosphatase (ACP), alkaline phosphatase (AKP), and glutathione peroxidase (GSH-PX) activity. The mRNA expression of immune-related genes in the head kidney of C. auratus was measured. Among them, the interferon gamma gene (IFN- γ) and tumor necrosis factor-α (TNF-α) showed higher expression after 3 and 4 weeks of feeding (P < 0.05). The expression of interleukin-1 (IL-1) only being significantly upregulated by 10⁹ cfu/g of JW after 1 week of feeding (P < 0.05). The upregulation of interleukin-4 (IL-4) increased over time from 1st to 4th week. The expression of interleukin-10 (IL-10) and interleukin-12 (IL-12) showed an opposite expression pattern with IL-10 significantly upregulated and IL-12 significantly downregulated by JW containing diets at 2, 3, and 4 weeks of post-feeding (P < 0.05). Moreover, fish fed with JW supplemented diets showed significantly improved survival rate after A. hydrophila infection. The analysis of the genome of JW revealed several features aiding host health and being relevant to the GIT adaptation. Four bacteriocins, three Polyketide Synthetase (PKS), and five Nonribosomal Peptide-Synthetase (NRPS) gene clusters were identified in the genome. In summary, the above results clearly proved that B. velezensis JW has the potential to be developed as a probiotic agent in aquaculture.

Keywords: Antibacterial activity; Bacillus velezensis; Bacteriocin; Fish immunity; Genome sequencing.

MeSH terms

Animal Feed / analysis
Animals
Bacillus / chemistry*
Bacterial Infections / immunology
Bacterial Physiological Phenomena
Diet / veterinary
Fish Diseases / immunology*
Fish Proteins / genetics
Fish Proteins / immunology*
Gene Expression Regulation / immunology*
Goldfish / genetics
Goldfish / immunology*
Immunity, Innate / genetics*
Probiotics / pharmacology*

Substances

Fish Proteins