Fate of <i>Bacillus thuringiensis</i> in soil: effect of soil pH and organic amendment

Abstract

Bacillus thuringiensis spores germinated, grew, and sporulated in soils of neutral pH amended with alfalfa or casein. Numbers of viable spores of B. thuringiensis increased 100-fold and more than one million spores/g soil were maintained throughout a 3-month incubation period. B. thuringiensis spores apparently germinated but the resulting vegetative cells did not survive in acid soils amended with alfalfa or casein. It appears that B. thuringiensis spores can remain viable for long periods of time in soil and that the organism can compete successfully under conditions favoring the bacillus component of soil microbial populations.