Comparative Study Of Cellulase Activity In Representative Beetles

Cellulose is the most prevalent sources of renewable biomass in nature. The utilization and conversion of cellulose are crucial to settling the issue of energy crisis, food shortage and environmental pollution. Degradation of cellulose using cellulose is the most powerful method, and recently, the animal cellulase became the hotspot of cellulase study. The order Coleoptera (beetles) is the largest group of the organism. It was suggested to be a potential resourse for powerful cellulase because of its diversity of species and feeding strategies. However, the cellulolytic activites were only quantitatively determined in very few species and the comparatively study lack especially.The main conclusions are shown as following:1. There are complete cellulase systems in most of the beetles while the enzyme activity of endoglucanase (Cx) was not detected in the larva of Massicus raddei.2. The optimal conditions of cellulase in most species are40-60℃and pH=4-6. Furthermore, significant differences of cellulolytic activites among different species were detected.3. The temperature. pH and the interaction between them all effected the enzyme activity of cellulase significantly in each beetle.4. The enzyme properties correlate with taxonomic classification to a certain extent, however the cluster analysis tree is inconsistent with the phylogentic tree. The different feeding strategies may also contribute to, but do not determine the difference of enzyme properties.5. The highest enzyme activity of endoglucanase (Cx) was detected in larva of Ambrostoma quadriimpressum and Cryllorhynobites ursulus, and the the highest enzyme activity of β-glucosidase was detected in larva of Ambrostoma quadriimpressum, indicating the potential application of cellulase of leaf beetles.6. The highest enzyme activity of exoglucanase (C1) was observed at pH9and70℃in the larva of longhorn beetle, Semanotus bifasciatus. The potential applications in the biofuel industry was suggested due to its high relative activity at alkaline pH and high temperature.