Whole genome analysis of intestinal source Bacillus and its effect on the prevention and control of hybrid snakehead (Channa maculata ♀ × Channa argus ♂) nocardiosis

• Published in: Frontiers in Marine Science Vol. 11
• Main Authors: Zhou, Tingting, Cai, Ping, Li, Junwei, Li, Zhongsheng, Dan, Xueming, Huang, Xiande, Zhang, Xiaoyong
• Format: Journal Article
• Language: English
• Published: Lausanne Frontiers Research Foundation 08.02.2024; Frontiers Media S.A
• Subjects: Antibiotics; Aquaculture; Bacteria; Bacteriostats; Biological control; Carbohydrates; Channidae; Circular DNA; Diet; Disease control; Drug resistance; Encyclopaedias; Enzymes; Freshwater; Freshwater aquaculture; Gene clusters; genome sequence; Genomes; Gram-positive bacteria; growth; hybrid snakehead; Inland water environment; Intestine; Lactones; Lysinibacillus sphaericus AEB18; Metabolites; Microbiological strains; Microorganisms; Mortality; Nocardiosis; Peptides; Polyculture (aquaculture); Polymerase chain reaction; Prevention; probiotic; Probiotics; Production increases; Secondary metabolites; Synthetic peptides; Terpenes; Water temperature; Beijing China; China; Montenegro
• ISSN: 2296-7745; 2296-7745
• DOI: 10.3389/fmars.2024.1254806

In order to explore the antagonistic mechanism of Lysinibacillus sphaericus AEB18 against Nocardia seriolae , the whole genome of strain AEB18 was sequenced, and the effect of strain AEB18 in controlling nocardiosis of hybrid snakehead was verified in vitro and in vivo . Strain AEB18 genome was a circular DNA of 4,653,716 base pairs (bp) and GC content of 37.4%, predicting 4,529 coding genes, 108 tRNAs, 37 rRNAs, and 95 non-coding (nc)RNAs. The eggNOG (Non-supervised Orthologous Groups), GO (Gene Ontology), KEGG (Kyoto Encyclopedia of Genes and Genomes) and the CAZy (Carbohydrate-Associated Enzyme) database annotated the strain AEB18 genome to 3,965, 3,325, 2,061, and 112 genes, respectively. Furthermore, nine gene clusters, including polyketones, non-ribosomal synthetic peptides, β-lactones, terpenes, ribosomal synthetic peptides, and other secondary metabolites with bacteriostatic effect were obtained through the prediction of secondary metabolites of strain AEB18. After the addition of L. sphaericus AEB18 (1 × 10 9 CFU/g) with a mass fraction of 1% to the basal diet for 21 days, the weight gain rate and the activity of amylase in intestinal chyme of hybrid snakehead were significantly increased ( P < 0.05). In addition, hybrid snakehead fed with L. sphaericus AEB18 supplemented diets showed significantly reduced mortality rate ( P< 0.05) after N. seriolae infection, compared with the control group (mortality rate was 100%). Overall, L. sphaericus AEB18 positively affected hybrid snakeheads, promoted growth and reduced mortality rate of hybrid snakeheads with nocardiosis. Taken together, the L. sphaericus AEB18 possesses great potential as a biocontrol agent, which can be commercially developed to improve disease control in freshwater aquaculture.