pH、温度和盐度对单环刺螠消化酶和溶菌酶活力的影响

采用L25(56)正交试验法测定了不同pH(6、7、8、9、10)、温度(10、15、20、25、30℃)和盐度(15、20、25、30、35)对体质量为(71.2±8.5)g的单环刺螠肠蛋白酶、淀粉酶、纤维素酶和脂肪酶活力的影响,以及不同盐度对单环刺螠血液溶菌酶活力的影响。试验结果表明,单环刺螠肠消化酶活力的最适环境条件分别为,蛋白酶:pH 8、温度30℃、盐度35;淀粉酶:pH 9、温度25℃、盐度25;纤维素酶:pH6、温度30℃、盐度35;脂肪酶:pH 6、温度25℃、盐度30。盐度15和20两组单环刺螠血液溶菌酶活力均先降后升再降,而盐度30和35两组则先升后降。至处理第4d,各试验组溶菌酶活力依次为:盐度3025352015,盐度15和20两组溶菌酶活力显著低于盐度较高试验组(P0.05)。盐度25~35、pH 6~9为单环刺螠适宜的环境条件,高温(25~30℃)下其消化酶活力较高,而低盐度(15~20)下其消化酶活力和免疫能力明显降低。

Effects of pH,Water Temperature and Salinity on Activities of Intestinal Digestive Enzymes and Serum Lysozyme in Echiuran Worm Urechis unicinctus

The effects of pH of 6, 7, 8, 9, and 10, temperature of 10 ℃, 15 ℃, 20 ℃, 25 ℃, and 30 ℃, and salinity of 15, 20, 25, 30, and 35 on activities of intestinal digestive enzymes and effects of salinity of 15, 20, 25, 30, and 35 on activities of serum lysozyme activity in hemolymph were studied in echiuran worm Urechis unicinctus by an orthogonal experiment.The results showed that the maximal protease activity was observed under conditions of pH 8, 30 ℃ and salinity of 35;amylase under pH 9, 25 ℃, and salinity of 25;cellulase under pH 6, 30 ℃, and salinity of 35;and lipase under pH 6, 25 ℃, and salinity of 30.The lysozyme activity in the echiuran worm at salinity of 15 and 20 were shown to be first decreased, then increased, and dropped again, while the lysozyme activity in a salinity of 30 and 35 were shown to be increased first and then declined.The order of lysozyme activity at various salinities in 4 days was descendantly arranged as salinity 30>25>35>20>15, and the lysozyme activities were significantly lower in a salinity of 15 and 20 than that in other treatments with higher salinity.The findings indicated that echiuran worm had a suitable salinity of 25-35 and pH 6-9, and the higher digestive enzyme activity under temperature of 25-30 ℃.However, significantly lower activities of digestive enzymes and lysozyme were found at low salinity of 15-20.