Dietary administration of Bacillus amyloliquefaciens R8 reduces hepatic oxidative stress and enhances nutrient metabolism and immunity against Aeromonas hydrophila and Streptococcus agalactiae in zebrafish (Danio rerio). Issue 86 (March 2019)

• Record Type: Journal Article
• Authors: Lin, Yu-Sheng; Saputra, Febriyansyah; Chen, Yo-Chia; Hu, Shao-Yang
• Is Part Of: Fish & shellfish immunology. Issue 86(2019)
• Page Start: 410
• Page End: 419
• Publication Date: 2019-03
• Subjects: Bacillus amyloliquefaciens -- Zebrafish -- Xylanase -- Oxidative stress -- Innate immunity; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2018.11.047
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: Zebrafish ( Danio rerio ) are an excellent model for assessing the beneficial effects of probiotics before applying them in aquaculture. This study evaluated the effects on zebrafish of dietary supplementation with the probiotic Bacillus amyloliquefaciens R8, which heterologously expresses xylanase from rumen fungi. Nutrient metabolism, hepatic oxidative stress, and innate immunity against pathogen infections were investigated. Treated zebrafish received feed supplemented with B. amyloliquefaciens R8 for 30 days and then were compared to zebrafish that were fed a control diet. The treated fish showed significant increases in xylanase activity in the intestines. The livers of the treated fish showed increased mRNA expressions of glycolysis-related genes of hexokinase, glucokinase, glucose-6-phosphatase, and pyruvate kinase; and higher enzyme activities of 3-hydroxyacyl-coenzyme A dehydrogenase and citrate synthase which are associated with fatty acid β-oxidation and mitochondrial integrity. The livers of treated fish also showed decreased mRNA expressions of oxidative stress-related genes ( SOD, Gpx, NOS2, and Hsp70 ) and an apoptotic gene ( tp53 ), as well as increased expression of an anti-apoptotic gene ( bcl-2 ). The probiotics-treated fish had increased expression of innate immune-related genes ( IL-1β, IL-6, IL-21, TNF-α, and TLR-1, -3, and -4 ). Following challenge with Aeromonas hydrophila and Streptococcus agalactiae, treated fish showed increased a higher survival rate than control fish. Overall, results showed that the administration of xylanase-expressing B. amyloliquefacien s R8 can potentially improve nutrient metabolism and hepatic stress tolerance, and enhance immunity and disease resistance against A. hydrophila and S. agalactiae in zebrafish. Highlights: Bacillus amyloliquefaciens expressing recombinant xylanase increased xylooligosaccharide (XOS) levels in fish intestines. Dietary supplementation with B. amyloliquefaciens R8 enhanced expression levels of metabolism-related genes and enzyme activities in the fish liver. The use of B. amyloliquefaciens R8 improved expression levels of oxidative stress-related genes in the fish liver. The administration of B. amyloliquefaciens R8 enhanced the innate immunity of fish against A. hydrophila and S. agalactiae infection.