[Bacillus thuringiensis Berliner mutants resistant to various antibiotics and showing alterations of sporulation]

Mutants resistant to oxytetracyclin, erythromycin and neomycin but not to streptomycin, often shown, in the absence of antibiotic, alterations in sporulation: slight or pronounced temperature-sensitive character between 30 and 37 degrees C, slight thermoresistance of refractive spores formed at 30 degrees C, oligosporogenic character at 30 degrees C.