【作者】 李振达；

【导师】 陈小娥；

【作者基本信息】 浙江海洋学院 ， 食品加工与安全， 2011， 硕士

【摘要】 为了确定壳寡糖对南美白对虾和三疣梭子蟹生长和免疫状况的影响。以壳聚糖为原料,用壳聚糖酶酶解制备壳寡糖,对酶解条件进行了研究。通过对酶解液超滤、冷冻干燥等工艺制备了不同脱乙酰度、不同分子量级别的壳寡糖。将制得的壳寡糖应用到南美白对虾和三疣梭子蟹养殖中,研究了壳寡糖添加量、脱乙酰化度、分子量级别对其生长及免疫力的影响,确定出壳寡糖在南美白对虾和三疣梭子蟹养殖中的最佳添加量,为壳寡糖在水产养殖中的进一步应用推广奠定基础。研究表明壳聚糖最适酶解条件为:酶用量3.0mL/g、底物浓度3.0%(w/v)、温度45℃、pH5.8、反应时间12h。通过对酶解液进行超滤、冷冻干燥后,得到了不同脱乙酰度(74.5%、85.3%、93.2%)、不同分子量级别(3kDa以下、3kDa～5kDa和5kDa～10kDa)的壳寡糖。研究结果表明,与对照组相比,在基础饲料中添加壳寡糖可以显著提高南美白对虾的生长速度、成活率、血细胞密度,酸性磷酸酶、溶菌酶和过氧化物酶活力(P<0.05),当壳寡糖添加量为0.25g/kg和0.5g/kg时促进效果较好。壳寡糖添加量为0.25g/kg和0.50 g/kg时可在一定程度上提高南美白对虾血清中的总超氧化物歧化酶活力,但与对照相比差异不显著(P>0.05)。不同的脱乙酰度和不同的分子量级别对南美白对虾的生长和非特异性免疫影响差异不显著(P>0.05),随着脱乙酰度的增加和分子量的减小促进效果呈非规律性上升趋势。综合考虑饲料成本和壳寡糖对南美白对虾生长和免疫力的影响,确定壳寡糖在南美白对虾养殖中的添加量为0.25~0.50 g/kg,壳寡糖的脱乙酰度大于74.5%,分子量10kDa以下。在基础饲料中添加壳寡糖可以显著提高三疣梭子蟹的增重率(P<0.05)。添加壳寡糖可明显三疣梭子蟹的血细胞密度和成活率(P>0.05),脱乙酰度和分子量级别对其影响不显著(P>0.05)。在基础饲料中添加壳寡糖可以显著性提高三疣梭子蟹血清中总超氧化物歧化酶、酸性磷酸酶、溶菌酶和过氧化物酶活力(P<0.05),当添加量为1.0g/kg时促进效果最好。脱乙酰度对三疣梭子蟹的生长和非特异性免疫影响差异不显著。壳寡糖分子量级别小于5kDa与5kDa～10kDa相比,三疣梭子蟹生长率显著提高(P<0.05)。综合考虑决定壳寡糖在三疣梭子蟹饲料中的添加量为1.0g/kg,壳寡糖的脱乙酰度大于74.5%,分子量5kDa以下。更多还原

【Abstract】 To determine the effects of chitooligosaccharides on growth and immunity in Litopemaeus vannamei and Portunus trituberculatus.This paper studies the enzymes solution of the preparation of chitooligosaccharides. The chitooligosaccharides are prepared into different degrees and molecular levels from enzymolysis liquid by ultrafiltration and frozen drying. The chitooligosaccharides prepared were used in the culture of Litopemaeus vannamei and Portunus trituberculatus. The effect of addition, degrees and molecular levels were studied to make sure the function of chitooligosaccharides used in Litopemaeus vannamei and Portunus trituberculatus. The study can be the foundation for the chitooligosaccharides in the further application and promotion in aquaculture.Results show that the optimal temperature,pH value,concentration of substrate , reaction time and enzyme concentration are 3%,3mL/g,45℃,5.8,12hours. The different degrees (74.5%,85.3%,93.2%)and different molecular levels (less than 3kDa,3k～5kDa and5k～10kDa)chitooligosaccharides were prepared by ultrafiltration and frozen drying.The research shows that oligosaccharides can significant improve weight gain rate, survival rate , the main hemocyte densities , the activities of acid phosphatase, lysozyme and peroxidase of Litopenaeus vannamei compared with blank group(P<0.05), the effect is better than others when the addition of oligosaccharides is 0.25g/kg and 0.50g/kg. To some extent ,When the addition of oligosaccharides is 0.25g/kg and 0.50g/kg can improve the activity of total superoxide dismutase , but there was no significant difference in total superoxide dismutase activity between test group and blank group(P>0.05).The different degrees and molecular levels have no significant influence in the growth and non-specific immunization of Litopenaeus vannamei(P>0.05)with the increase of degree and the decrease molecular weight the promotive effect rising. By comprehensive consideration, the suitable addition level , degree level and molecular level used in Litopenaeus vannamei are 0.25～0.50 mg/kg, 74.5% and less than 10kda.Chitooligosaccharides added into basal feed can significant increase the growth rate of Portunus trituberculatus(P<0.05).It can also increase the main hemocyte densities and survival rate of Portunus trituberculatus, The degrees and molecular levels have no significant influence in the main hemocyte densities(P>0.05). The result showed that chitooligosaccharides can significant enhance the activities of acid phosphatase, total superoxide dismutase, lysozyme, peroxidase and the blood corpuscle density of Portunus trituberculatus ( P < 0.05 ) , the effect is better than others when the addition of oligosaccharides is 1.0g/kg. The degrees have no significant influence in the growth and non-specific immunization of Portunus trituberculatus. When the molecular weight is less than 5kDa the growth of Portunus trituberculatus are significant improved Compared with 5kDa～10kDa. In conclusion, the suitable addition level, degree level and molecular level used in Portunus trituberculatus are 1.0g/kg, more than74.5%, less than 5kda.更多还原