Characterization and evaluation of repellent effect of essential oil of mangifera indica L. from Kenya

Publication Type

Journal Article

Journal Name

Biocontrol Science and Technology

Publication Date

1-1-1999

Abstract

The δ-endotoxin crystals of a Bacillus thuringiensis isolate active against the tsetse fly, Glossina morsitans, were isolated from a nutrient broth culture by low speed centrifugation. Analysis of these crystals by denaturing gel electrophoresis revealed that the major component of the crystal δ-endotoxin was a protein of tool. wt ≃ 120 000. Upon solubilization under alkaline pH and reducing conditions, the crystal yielded a toxin of mol. wt ≃ 64 000. Treatment of the toxin with bovine trypsin resulted in a shift in the mol. wt to a toxin of ≃ 62 000, while treatment with bovine chymotrypsin gave a toxin of ≃ 60000. Methyl green staining revealed that the endotoxin was phosphorylated, while staining with periodic acid schiff reagent showed that it was glycosylated. The carbohydrate moiety was of the high mannose type as shown by staining with fluorescein isothiocyanate conjugated to concanavalin A. Following gel permeation chromatography on a Superose 12 column, the solubilized toxin resolved into six main protein peaks, two of which had trypsin-like activity. The ≃-endotoxin caused mortalities in the tsetse, G. morsitans morsitans (LC50 of 42.4 μg ml-1) and 4th instar Chilo partellus larvae (LC50 of 53.8 μg ml-1), but had no effect on 3rd instar Aedes aegypti larvae.

Keywords

Bacillus thuringiensis, Chilo partellus, Glossina morsitans, Insecticidal crystal proteins, δ-endotoxin

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