Influence of pH on the toxicity and survival of total cells and spores of Bacillus thuringiensis.
B. thuringiensis (Bt) is one of the most important microorganism among those studied because of their entomopathogenic potential against insect plagues and vectors. In this work, the pathogenicity and survival of total cells and spores of three autochthonous strains of B. thuringiensis isolated from Argentine soils (A61, A27 and A68) and the commercial strain HD-1 were studied at different ion hidrogen concentrations (pH = 4.4; 5.4; 7.4; 8.4; 9.4 and 10.4) under laboratory conditions. The greatest antimicrobial effect on the number of spores and total cells was observed at pH 4.4 with a great decrease after 72 hours' growth. Comparing the survival percentage of total cells and spores; pH 5.4 was the one which allowed the higher relative tolerance (survival) among the studied strains. No decrease in pathogenicity was observed in the investigated serotypes at different pHs in bioassays against Cydia pomonella. Two soil strains of Bt (A61/A27) and the Bt (HD-1) of commercial origin caused the highest mortality of the target insect. The sotto serotype (A68), however, did not produce this effect.
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Departamento de Agronomía, Universidad Nacional del Sur, Bahía Blanca, Argentina. simoni@edu.ar
Sagardoy
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D001118:Argentina; D001413:Bacillus thuringiensis / Q000472:pathogenicity; D001427:Bacterial Toxins / Q000633:toxicity*; D006863:Hydrogen-Ion Concentration; D012988:Soil Microbiology
D001427:Bacterial Toxins