Characterization of an Argentine isolate of Bacillus thuringiensis similar to the HD-1 strain

Abstract

We report the characterization of an Argentine isolate of Bacillus thuringiensis (INTATA24-6) similar to the HD-1 strain, which harbors a cryptic cry2Ab gene that apparently is transcribed but not translated into a protein. INTATA24-6 showed a Rep-PCRpattern identical to the HD-1 strain, a plasmid pattern that resembled that of this strain and cry1 and cry2 genes as HD-1. Screening of cry1 and cry2 genes showed that INTATA24-6 harbors only cry1Ac and cry2Ab genes. Furthermore, crystalline inclusions of INTATA24-6 exhibit a bipyramidal shape, typical of Lepidoptera-active B. thuringiensis strains, containing a major protein of ca. 130 kDa toxic to Epinotia aporema Wals. (Lepidoptera: Tortricidae) larvae. Neither the flat-square to cuboidal crystal nor a ca. 65 kDa protein typical of strains expressing Cry2 proteins were detected in INTATA24-6. In agreement with this information, parasporal crystals of INTATA24-6 did not show toxicity to Aedes aegypti L. (Diptera: Culicidae) larvae. Gene transcription analyses suggested that the cry2A gene might be cryptic in INTATA24-6 despite its transcription at different sporulation stages.