Microbial Ecological Studies on Bacillus thuringiensis

IV. The Growth of Bacillus thuringiensis in Soils of Mulberry Plantations

Abstract

Soils were collected from 24 mulberry plantations in Saitama Prefecture and were inoculated with spores of Bacillus thuringiensis strain AF101. The growth of B. thuringiensis was not observed for more than 30 days after the inoculation in all soil samples so far as tested and a possible lack of germination factors in soils was suggested. The effect of pH, total carbon and total nitrogen of soil samples on the growth of B. thuringiensis was investigated using sterilized soils. Spores of B. thuringiensis could germinate and grow in 13 out of 17 sterilized soil samples. B. thuringiensis could grow in soils with a pH range of 5.5-7.1, but not in soils with a pH range of 4.0-5.4. Total carbon and nitrogen contents did not affect the growth of B. thuringiensis.