Q969.453.806Detection of Cellulases and the Relationship Between Enzyme Activity and Development of Musca domestica : Q969.453.806Detection of Cellulases and the Relationship Between Enzyme Activity and Development of Musca domestica

Abstract

For understanding whether or not Musca domestica has an ability to hydrolyze cellulose,the activities and characteristics of cellulases from M.domestica were examined with the 3,5-dinitrosalicylic acid(DNSA) method.Then the composition and activity change of M.domestica cellulases were investigated during its development.The results showed that M.domestica in the different developmental stages had the filter paper enzyme activity,the activity-range being 0.85(± 0.035) IU mg-1to 10.45(± 0.050) IU mg-1.The cellulase components included β-glucosidase(BG),endo-β-1,4 glucanase(EG) and exoβ-1,4-glucanase(CBH),which were detected with the special substrate of 1% salicin,1% carboxymethylcellulose(CMC) and 1% microcrystalline cellulose(MCC),respectively.Under the condition of pH 5.6,for the three enzymes,the optimum reaction temperature and time were 50 ℃ and 60 min.They had good heat stability in vitro when being kept in 50 ℃ for 1 hour.Activity of the cellulases increased gradually with its development(P 0.05).The lowest enzyme activity showed in the ovule stage and the highest enzymatic activity in the imago stage.At the optimum reaction condition,the activities of BG,EG and CBH were 7.96(± 0.065) IU mg-1,9.76(± 0.080) IU mg-1 and 10.86(± 0.091) IU mg-1 respectively.The CBH activity was the highest,and the BG the lowest in M.domestica life cycle.With increasing crude fiber in the forage of M.domestica larvae,cellulase activity of the third instar larvae was also increased(P 0.05),without a significant deviation of mean weight and stem length of the third instar larvae compared to the control group(P 0.05).The results suggested a complete enzyme system of cellulases in M.domestica and a close relationship between the enzyme activity level and the development of M.domestica.