4种植食性甲虫肠道内纤维素酶活性的比较

Comparation of Gut Cellulase Activity in Four Herbivorous Beetles

为比较和客观评价昆虫体内纤维素酶的活性,在不同温度及pH值下测定杨叶甲、二纹柱萤叶甲、紫榆叶甲成、幼虫及双条杉天牛幼虫消化道内3类纤维素酶的活性。结果表明:4种甲虫体内均有消化纤维素的完整酶系,3种叶甲成、幼虫体内各纤维素酶的最适温区为40～60℃、最适pH值范围为4～6,在高温和强碱条件下均未能检测出酶活性;双条杉天牛幼虫C1酶活性在强碱pH=9和70℃条件下活性最高,Cx酶和β-葡萄糖苷酶活性低于3种叶甲的成虫和幼虫,C1酶活性显著高于3种叶甲的成虫和幼虫。温度和pH值对昆虫体内纤维素酶活性有显著的影响,甲虫取食习性的不同可能导致体内纤维素酶活性的差异,酶活性的差异是否受到昆虫亲缘关系的影响还需要进一步研究。

To compare and estimate the cellulose enzyme activity in different insects, the paper presented a comprehensive analysis of enzyme activity from the gut juices of four herbivorous insect species （larvae and adults of three leaf-eating beetles, Chrysomela populi, Ambrostoma quadriimpressum and Gallerucida bifasciata, and larva of a trunk- borer, Semanotus bifasciatus）. The results showed that there were complete cellulase systems in these four beetles, and that both temperature and pH had a significant impact on the enzyme activity in the gut contents. For both larvae and adults of three leaf beetles, the optimal conditions of enzyme activity were 40 - 60 ℃ and pH 4 - 6, and the enzyme activity could not be detected under high temperature and high pH conditions. However, in trunk-borer of S. bifasciatus the highest enzyme activity of exoglucanase （C1） was observed at pH 9 and 70 ℃. In addition, the enzyme activities of endoglucanase （Cx） and fl-glucosidase in S. bifasciatus were lower than that of the leaf beetles, while the enzyme activity of C; was much higher than that of these leaf beetles. The results indicated that temperature and pH had significant influence on insect cellulose enzyme activity. The different feeding habits and the phylogenetic relationship may result in different enzyme activity.