Genetic basis for alkaline activation of germination in Bacillus thuringiensis subsp. israelensis.

Differences in activation between spores from strains of Bacillus thuringiensis subsp. israelensis with and without the toxin-encoding plasmid pBtoxis are demonstrated. Following alkaline activation, the strain bearing pBtoxis shows a significantly greater germination rate. Expression of just three genes constituting a previously identified, putative ger operon from this plasmid is sufficient to produce the same phenotype and characterizes this operon as a genetic determinant of alkaline activation.