Multiple endo-beta-1,4-glucanases present in the gut fluid of a defoliating beetle, Podontia quatuordecimpunctata (Coleoptera: Chrysomelidae).

ABSTRACT

Endo-beta-1, 4-glucanase (EC 3.2.1.4) activity was measured in the gut fluid of phytophagous insect Podontia quatuordecimpunctata Linnaeus (Coleoptera Chrysomelidae) in different days of development. The eight day-old larva showed maximum activity with 1.73 U mg(-1) of protein, which was confirmed by gel zymography. In zymogram, using Carboxymethyl Cellulose (CMC) as substrate, four distinct cellulolytic protein bands were detected in leaf borer gut fluids through out of its development. The optimum temperature and pH were 60 degrees C and 5.0, respectively. This endo-beta-1,4-glucanase showed maximum stability at 20-45 degrees C with approximately 20% remaining activity. Zymography also showed complete loss of endo-beta-1,4 glucanase activity at 55 degrees C. This is the first report that the cellulolytic enzyme is produced in the gut of P. quatuordecimpunctata through the whole developmental stages, from the 1st instar to the adult, except for pupae.