Study On The Properties And Purification Of Endo-β-1, 4-Glucanase From Odontotermes Formosanus(Isoptera:Termitidae)

The cellulose degradation dependes on the synergistic effect of endo- 3 -1.4-glucanase, exo- B-1,4-glucanase and B -glucosidase on lignocellulose material at least. No matter what is higher termite or lower termite, endogenous enzyme are mainly endo- B-1,4-glucanase (Cx, EGase) and B -glucosidase, which are secreted by the epithelium of midgut and salivary gland. There are mass symbiotic bacteria and protozoans in the hindgut of lower termite, which could produce multiple cellulase for hydrolysing plant cellulose. But higher termite is devoid of protozoans in the hindgut. symbiotic fungus from the nest play an important role in cellulose degradation, termite could obtain extrinsic cellulase for digesting the lignocellulose from food.The paper mainly compared the discrepance of cellulase activities from termites living different habit, and illustrated the secretion mechanism of cellulase in termite. At the same time, endoglucanase component from subterranean termite Odontotermes formosanus was purified by ion-exchange chromatography. some properties of this enzyme were elucidated. Through the observation of fine structure, it will clarify the role of salivary gland of O. formosanus in the secretion of cellulase.Main results of this dissertation included the following parts:1. Study on the optimal conditions of cellulase from termitesThe optimal pH when Cx from Reticulitermes flaviceps reacted with substrate sodium carboxymethylcellulose (CMC-Na) was between 5.0-7.4 and 5.0-6.2 when BG enzyme was reacted with substrate salicin, the relation between activities of enzymes and relevant pH values accorded with Quadratic models. The optimal pH values were 6.7 and 5.2 respectively for Cx and BG. the highest activities were 1 066.4 U/termite and 664.0 U/termite respectively. Cx activities was significantly related to temperature linearly. BG acticities was alsosignificantly related to temperature, but the relation could be described with a exponential model. The activities of Cx and BG had positive correlated with their relevant concentration of substrates, respectively. The relation between Cx activity and time accorded with power model, but which between BG activity and time could be displayed S model.2. Comparison of cellulase activities among termitesComparison of the cellulase activities among workers (or pseudoergate) of five termites species, it indicated that workers of damp-wood termite R. leptomandibularis had the highest activity of cellulase against CMC-Na. which was 3.5 times higher than that of O. formoscmus. From activity of P-glucosidase R. leptonuindibitlaris was the highest. O. formosanus the second, and dry wood termite Cry. pingyungensis pseudoergate the lowest. However, the cellulase activity of Cry. pingyangensis against CMC-Na in the oral cavity was the highest. Subterranean termite O. formosanus had the largest P-glucosidase activity in the head compared to other tested termites, the second were R. flaviceps and R. leptomandibularis.The strongest digestibility of CMC-Na were in the foregut for R. leptomandibularis. R. flaviceps and Cry. pingyangensis. where the activity of cellulase against CMC-Na was higher than that in the midgut and hindgut. But in the midgut ofC.formosanus the highest activities of cellulase against CMC-Na were observed, and in the hindgut of R. leptomandibularis and R. fluviceps there were no obvious variance among the three parts of gut.In the foregut. Cry. pingyangensis and C. formosunus had the highest B-glucosidase activity among the tested five termites, the latter also had the highest B-glucosidase activity in the midgut. The digestion of salicin for O. formosanus was concentrated in the midgut and hindgut, but the amount of p-glucosidase was very low. R. leptomundibularis and R. flaviceps had the strongest digestibility of salicin in the hindgut. where R. leptomandibularis took the leading place among the other termites.3. Purification of endoglucanase of O. formosanusThe purification of the cellulase from O. formosanm workers was ac...