To study the fitness of Bacillus thuringiensis to survive in natural and artificial, terrestrial ecosystems

• Main Author: Prabhakar, Amit
• Format: Thesis
• Language: unknown
• Published: 2010
• Subjects: QK Botany; QR Microbiology; Antarctic; The Antarctic; Antarc*; Antarctica
• Online Access: http://gala.gre.ac.uk/id/eprint/8107/

The present work is the first report of the Multi Locus sequence typing (MLST) of the B. thuringiensis strains isolated from the phylloplane of the clover leaf. A clonal population structure was indicated, although greater variation in sequence types (STs) was discovered in previous collections of B. cereus/B. thuringiensis. The three techniques of DGGE, T-RFLP and MLST were compared for the first time to judge whether the fingerprinting and typing techniques provide the same level of resolution in the structure of the bacterial communities. The techniques resulted in interesting findings: (a) the clustering of fingerprints correlated with the time of collection; (b) there was variability in the T-RFLP profiles, possibly due to the choice of restriction enzymes used in the study; (c) the rpoB gene gave better resolution in DGGE than 16S rDNA; and (d) DGGE types detected ambiguities in the nucleotides. The project is the first report of experiments to study natural colonisation of a plant by B. thuringiensis, causing a pathological effect on a susceptible insect. The pathogenic effect or interaction of Bt naturally colonising Brassica plants on neonate larvae of Pieris brassicae has been achieved. Initial screening studies of B. thuringiensis from the Antarctica have been completed. The two most important genes coding for the toxins cry1 and cry2 have been amplified and the sequences have been submitted to the NCBI database. The strains from Antactica have also been screened for the nematicidal and enterotoxic toxins. The Antarctic B. thuringiensis strains have been found to possess large and irregular shaped crystals. The sub lethal and lethal effects of crystal preparations from Antarctic B. thuringiensis isolates on Orchesella cincta, Folsomia candida and Seira domestica has been achieved, showing moderate level of toxicity against these springtails.