University of Khartoum

Identification of Bacillus thuringiensis and Bacillus sphaericus by conventional methods and parasporal crystal formation

Identification of Bacillus thuringiensis and Bacillus sphaericus by conventional methods and parasporal crystal formation

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Title: Identification of Bacillus thuringiensis and Bacillus sphaericus by conventional methods and parasporal crystal formation
Author: Ahmed, Mubark
Abstract: In this study 80 samples of mosquitos' larvae comprising several genera were collected with the objective of isolation and identification of the bacillus species capable of producing insecticidal parasporal crystals namely B. thuringiensis and B. sphaericus. Larvae were collected from White Nile and Khartoum states. Samples were transported to the laboratory in a thermoflask on ice. In the process of isolation, larvae were treated by heating at 80° C for 5min to kill vegetative cells. They were then crushed using sterile glass beads and the preparation were streaked on nutrient agar and incubated at 37° C for 24 hr. Using conventional biochemical methods, 74 isolates were identified as Bacillus spp. The species isolated included B. thuringiensis, B. sphaericus, B. cereus, B. mycoides, B. alvei, B. megaterium, B. licheniformis, B. subtilis, B. pumilis, B. circulans, B. polymyxa, and B. coagulans 74 isolates were identified as Bacillus spp. of which 3 were B. thuringiensis and 5 were B. sphaericus. Isolated Bt and Bsph were further confirmed by their ability to produce parasporal crystals demonstrated using Gurr's improved R66 Geimsa stain, which was proved to be avaluable method for special staining of Bacillus thuringiensis and Bacillus sphaericus parasporal crystals.
URI: http://hdl.handle.net/123456789/8169
Date: 2015-04-02


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