Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China.
Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-Sen University, Guangzhou, 510080, China; Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510080, China.
Fish Shellfish Immunol. 2019 Jan;84:1115-1124. doi: 10.1016/j.fsi.2018.10.058. Epub 2018 Oct 26.
Probiotics are widely used for the improvement of animals' growth and health. However, few marine aquatic probiotics are applied and licensed in China. In this study, a Bacillus spp. strain was isolated from the Hulong grouper gastrointestinal tract, which was identified as a new strain of Bacillus subtilis and was named as 7k. B. subtilis 7k showed desirable capability of sporulation and resistance to heat, simulated gastric juice and simulated duodenum juice, indicating its potential as probiotics. Seven antimicrobial chemicals were found in the secretion of the B. subtilis 7k. B. subtilis 7k addition in diet promoted the growth rate of Hulong groupers. Moreover, B. subtilis 7k can inhibit infection by iridovirus, making B. subtilis 7k a suitable kind of probiotic for maintaining fishes' health. Our results also revealed that B. subtilis 7k induced non-specific immune response in Hulong grouper under virus infection. Hulong grouper fed by diets containing B. subtilis 7k at 10 and 10 cfu g for 4-8 weeks were significantly strengthened in serum lysozyme activity, serum alternative complement activity (ACH50), serum bactericidal activity, respiratory burst, superoxide dismutase activity (SOD), and phagocytic activity of head kidney leucocytes when compared with those fed by control diets. In conclusion, B. subtilis 7k was isolated and characterized to be a kind of process enduring, growth stimulating, immunity enhancing and health promoting probiotic using in grouper culture.
益生菌被广泛应用于改善动物的生长和健康。然而，在中国应用和获得许可的海洋水产益生菌却很少。本研究从青石斑鱼胃肠道中分离到一株芽孢杆菌，鉴定为枯草芽孢杆菌的一个新菌株，命名为 7k。枯草芽孢杆菌 7k 具有良好的孢子形成能力和耐热、耐胃酸、耐模拟肠液的能力，表明其具有作为益生菌的潜力。在枯草芽孢杆菌 7k 的分泌液中发现了 7 种抗菌化学物质。添加枯草芽孢杆菌 7k 于饲料中可促进青石斑鱼的生长速度。此外，枯草芽孢杆菌 7k 可抑制虹彩病毒感染，使其成为维持鱼类健康的一种合适的益生菌。我们的研究结果还表明，枯草芽孢杆菌 7k 在虹彩病毒感染下诱导青石斑鱼产生非特异性免疫反应。在虹彩病毒感染下，连续 4-8 周投喂含有 10 和 10ⁿcfu/g 枯草芽孢杆菌 7k 的饲料，可显著增强青石斑鱼血清溶菌酶活性、血清替代补体活性（ACH50）、血清杀菌活性、呼吸爆发、超氧化物歧化酶活性（SOD）和头肾白细胞的吞噬活性。综上所述，枯草芽孢杆菌 7k 被分离并鉴定为一种具有耐加工、促生长、增强免疫和促进健康作用的益生菌，可用于石斑鱼养殖。
