Shotgun sequencing of plasmids from Argentinean isolates of Bacillus thuringiensis

AMADIO A; BENINTENDE GB; ZANDOMENI RO

Iguazú, Argentina

Congreso; XL Reunión Anual SAIB; 2004

Bacillus thuringiensis (Bt) is a well known bacteria classified in many subspecies, which might produce proteins with different insecticidal activity. The genes coding for insecticidal proteins are usually in plasmids, which presents large variation in size, copy number, and little is known about coded genes. We have analyzed the plasmids profile of several Argentinean isolates of Bt by pulsed field gel electrophoresis (PFGE) and DNA sequencing. The plasmids changed their migration pattern at different run conditions, as expected for circular plasmids. A shotgun library from isolate INTA-FR7-4 was constructed and random clones were sequenced with universal primers at both sides of the insert. The total number of bases sequenced exceeds 200 kb. The contigs assembled correspond to more than 90 kb. None of the contigs showed large similarities when comparing with nucleotide databases. Preliminary annotation was performed searching protein databases with translated ORFs. Similarities found permit assign functions to several genes, including replicases and mobilization proteins. This approach allowed differentiating Argentinean isolates from other known classical strains not only by their plasmid profile but also by their sequence.