BAO Peng-yun1, LI Lu-yao1, XU Zhe2, CHEN Wei1, DING Jian-feng1,MA Yue-xin1*
1.Key Laboratory of Mariculture and Stock Enhancement in North China’s Sea, Ministry of Agriculture and Rural Affairs, Dalian Ocean University, Dalian 116023, China; 2.Dalian Huixin Titanium Equipment Development Company Limited, Dalian 116039, China
Abstract: A 8-week feeding trial was conducted to evaluate the effects of marine yeast Rhodotorula sp. H26 on growth, digestive enzyme activity, body composition, immunity and intestinal microbiota in the juvenile sea cucumber, Apostichopusjaponicus. Sea cucumber with body weight of (0.54±0.06)g were reared in a plastic bucket and fed diets containing H26 at 0 (control), 105 and 107 cells/g at water temperature of 16-24 ℃, and growth, digestive enzyme activity, body composition, immunity and intestinal microbiota were analyzed in the sea cucumber. There was significantly higher specific growth rate in the sea cucumber fed H26-supplemented diet at 107 cells/g for 4 weeks compared with the control group (P<0.05). The sea cucumber fed H26-containing diets at 105 and/or 107 cells/g for 4 and 8 weeks had significantly higher activities of pepsin, trypsin, amylase, and lipase and body wall crude protein and carbohydrate contents compared to those fed the control diet did (P<0.05). The ash content was shown to be significantly lower in the sea cucumber fed H26-containing diet at 107 cells/g for 8 weeks than that in the sea cucumber in the control group. In 8 week feeding trail, a significantly higher/lower contents of arachidonic acid (C20:4n-6)/ tetracosenoic acid were detected in the body wall of sea cucumber fed H26-containing diet at 105 cells/g than those fed the control diet. There were significantly higher/lower (C20:4n-6), dihomo-gamma-linolenic acid and adrenic acid/oleic acid, linoleic acid, eicosadienoic acid plus eicosatrienoic acid and eicosapentaenoic acid contents in sea cucumber fed H26-containing diet at 107 cells/g than those in the control group(P<0.05). In the 4 and/or 8 weeks, sea cucumber fed H26-supplemented diets at 105 and 107 cells/g had significantly higher respiratory burst in the coelomocytes, lysozyme activity in the coelomocyte lysate supernatant(CLS) and phenoloxidase activity in coelomic fluid supernatant (CF) and coelomocyte lysate supernatant (CLS) than those fed the control diet did(P<0.05). The phagocytic activity of the coelomocytes and lysozyme activity of the CF in sea cucumber fed H26-containing diet at 107 cells/g were significantly higher than those in the control group(P<0.05). Denaturing gradient gel electrophoresis revealed that the H26 did not significantly affect the composition of intestinal microbiota. These findings suggest that a diet supplemented with H26 can lead to improve the growth, to enhance digestive enzyme activity, to increase nutritive value and to stimulate the innate immune system of juvenile sea cucumber.
2019, Vol. 34 
