Characterization of polyvalent and safe Bacillus thuringiensis strains with potential use for biocontrol.

Sixteen Bacillus thuringiensis (Bt) strains were screened for their anti-insect, antibacterial and antifungal determinants by phenotypic tests and PCR targeting major insecticidal proteins and complements, chitinases, lactonases, beta-1,3-glucanases and zwittermicinA. Six strains had genes of at least two major insecticidal toxins and of insecticidal complements. With regard to fungal biocontrol, all the strains inhibited Fusarium oxysporum and Aspergillus flavus growth and four strains had all or most of the antifungal determinants examined, with strain Bt HD932 showing the widest antifungal activity spectrum.