Preliminary Molecular Analysis of a High-Pressure-Modified Type of Bacillus Thuringiensis Ssp. Israelensis, DNA- and Protein-Studies

摘要

During High Pressure (HP) inactivation process applied to spore preparation from Bacillus thuringiensis ssp. israelensis (Bti), a modified "more-resistant" HP Bti subpopulation can emerge! The present work is a preliminary molecular analysis of clonesissued from these two kinds of Bti, i.e. the modified subpopulation Bti[m] and the original commercially available bacteria Bti[+], The doubling times of these two clonal populations were found to be quite similar (30-35min) in standard 1 growth medium(Merck), at 30°C, with agitation. The preliminary molecular analysis was divided in Protein- and extrachromosomal DNA-studies: (i) Firstly, total-protein extracts were prepared from the batch cultures taking cell aliquots during both the exponential growth phase and the late stationary one. The data obtained with the SDS-PAGE show some differences between the protein patterns of Bti[+] and Bti[m] at both growth phases. (ii) Secondly, the extra-chromosomal DNA contents of Bti[+] and Bti[m] were analysed by agarose gel electrophoresis The presence of large size plasmid(s) was demonstrated in both Bti[+] and Bti[m] but some smaller size ones were discovered in Bti[+] only.