两种寡聚糖对罗非鱼生长及抗凡隆气单胞菌感染的影响

Effects of two oligosaccharides on growth and resistance to Aeromonas veronii infection in Tilapia nilotica

为探讨魔芋葡甘寡聚糖(K-GLMOS)和瓜胶豆半乳甘露寡聚糖(CB-GAMOS)作为鱼用抗生素生长促进剂替代品的可能性,将270尾同塘同规格的尼罗罗非鱼鱼种随机等分为3组。对照组喂商品罗非鱼种料;K-GLMOS组和CB-GAMOS组分别在饲料中添加1 000mg/kg的K-GLMOS和CB-GAMOS。饲喂28d后,观测鱼的增重率和料肉比;第30～45天测定不同处理组攻击凡隆气单胞菌BJCP-9株后的相对成活率,扫描电镜观察BJCP-9对肠道上皮的黏附;cell-ELISA法体外测试K-GLMOS和CB-GAMOS对BJCP-9黏附罗非鱼肠上皮的影响。结果显示,饲料中添加1 000mg/kg的K-GLMOS和CB-GAMOS显著促进了罗非鱼种的生长,降低了料肉比,并增强了抗BJCP-9感染的能力(P<0.05);1g/L的K-GLMOS或CB-GAMOS虽然均不能抑制BJCP-9的生长,但在体内、外均能抑制BJCP-9对罗非鱼肠道上皮细胞的黏附。5、50、500μg/mL的K-GLMOS和CB-GAMOS在离体模拟黏附试验中,表现出剂量依赖性的抗黏附作用(P<0.05)。表明K-GLMOS和CB-GAMOS作为鱼用抗生素类生长促进剂替代品具有广阔的前景,且抗黏附是其促生长和抗感染的机理之一。

To evaluate the feasibility of the Konjac gluco-mannan-oligosaccharide（K-GLMOS）and Cluster bean galacto-mannan-oligosaccharide（CB-GAMOS） as substitutes for antibiotic growth promoters in aquaculture,270 uniform tilapias from the same pond were assigned randomly to three groups.The control group was fed with a commercial tilapia diet and the K-GLMOS group and the CB-GAMOS group were fed with the same commercial diet supplemented with K-GLMOS and CB-GAMOS at 1 000 mg/kg,respectively.On day 28 of feeding,growth,disease resistance,and in vivo anti-adherence were determined by weight gain（%）,relative percent survival and scanning electron microscope,respectively.Furthermore,the inhibitory effect of K-GLMOS and CB-GAMOS on adhesion of Aeromonas veronii biovar.sobria（A.vbs）-BJCP-9 strain to tilapia enteric epithelia in vitro were assessed by cell-ELISA system. The K-GLMOS or CB-GAMOS supplemented at 1000mg/kg showed significant benefit to tilapia growth and disease resis-tance（ P0.05）,and the benefit may be correlated with their interfering in the contact of bacteria with host mucosal surface.Although the tested agents did not inhibit the growth of BJCP-9 in tryptic soy broth at 1g/L,both K-GLMOS and CB-GAMOS did inhibit the adhesion of A.vbs to tilapia enteric epithelia in vivo and in vitro. In vitro mimic assays showed that K-GLMOS and CB-GAMOS at the concentrations of 5,50,500μg/mL had the dose-dependent anti-adherence effect. These results indicated that K-GLMOS and CB-GAMOS were promising agents to antagonize bacteria and promote fish growth,and the anti-adherence of two oligosaccharides may be one of the mechanisms.