Enzymes for digestion of cellulose and other polysaccharides in the gut of longhorn beetle larvae, Rhagium inquisitor L. (Col., Cerambycidae)

The foregut, proximal and distal midgut, and hindgut of free living larvae of a bark runner, the longhorn beetle Rhagium inquisitor L., have been investigated for the presence of enzymes hydrolyzing a number of aryl-glycosides and polysaccharides representative of wood components. Specific activity was highest in the proximal midgut. No hydrolytic activity was found in control tissue, the extra-intestinal fat bodies. Activity was detected with CM-chitin, xylan, phosphoric-acid swollen cellulose, soluble starch, α-mannoside, β-glucoside, β-cellobioside and α-arabinoside. The highest activity was found on β-1,4-glucan and β-fucoside. No hydrolytic activity could be observed with crystalline cellulose. An identical molecular mass of 70 kDa for β-glucosidase and cellobiosidase was determined, corresponding to the major protein band. This suggests the absence of a cellobiohydrolase activity and thus a lack of fiber degradation ability. The endo-β-glucanase had a molecular mass of 32 kDa and an extremely broad pH-activity.