Isolating a new Streptomyces amritsarensis N1-32 against fish pathogens and determining its effects on disease resistance of grass carp. Issue 98 (March 2020)

• Record Type: Journal Article
• Authors: Li, Yanping; Hu, Shengbiao; Gong, Liang; Pan, Lifei; Li, Dongjie; Cao, Lina; Khan, Tahir Ali; Yang, Yahui; Peng, Yanan; Ding, Xuezhi; Yi, Ganfeng; Liu, Shaojun; Xia, Liqiu
• Is Part Of: Fish & shellfish immunology. Issue 98(2020)
• Page Start: 632
• Page End: 640
• Publication Date: 2020-03
• Subjects: Streptomyces amritsarensis -- Fish pathogens -- Immune-related gene -- Growth -- Grass carp; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2019.10.038
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: In this study, a Streptomyces strain was isolated from the soil samples of Yanghu Wetland Park in Changsha, Hunan Province. This strain showed excellent antimicrobial activity against 10 fish pathogens, as indicated by the results of the agar-diffusion and oxford cup assays. After 16s rDNA sequencing and physiological & biochemical analyses, it was identified as Streptomyces amritsarensis, namely for S. amritsarensis N1-32. Cytotoxicity test was performed, and the results exhibited that this strain had no toxicity to hepatic L8824 cell line from grass carp liver. The diets supplemented strain N1-32 at concentrations of 1 × 10 7 cfu/g and 1 × 10 9 cfu/g was used to feed fish. After 28 days, the expression levels of antioxidant-related genes Nrf2 and Keap1 in the liver and spleen were significantly up-regulated, and the expression of immune-related gene IgM was notably increased in the liver, kidney, head-kidney, and spleen. Toll-like receptor 4 (TLR4) gene expression was up-regulated in the spleen, and TLR4, myeloid differentiation factor 88 (MyD88) gene were up-regulated in the kidney. The survival rate of grass carp was significantly improved after pathogen infection. Whole-genome analysis of N1-32 showed that the strain harbored related genes, capability for producing substances that enhance the immunity of grass carp and inhibit pathogens. A total of 22 gene clusters were identified in the genome, including 5 terpene gene clusters, 4 nonribosomal peptide-synthetase (NRPS) gene clusters and 2 lantipeptide gene clusters. In summary, these results showed that strain N1-32 as a feed additive could regulate grass carp immunity and enhance the resistance of grass carp against fish pathogens. Highlights: A new strain, Streptomyces amritsarensis N1-32, was isolated and prospective to be applied to freshwater fish aquaculture. Streptomyces amritsarensis N1-32 has broad-spectrum antibacterial activity against freshwater fish pathogens. Streptomyces amritsarensis as probiotics was firstly applicated in aquaculture. Streptomyces amritsarensis N1-32 could significantly promote the immunity and growth of grass carps. Genome analysis of S. amritsarensis N1-32 revealed its potential for antimicrobial synthesis.