Alkali Resistance in a Strain of Bacillus cereus Pathogenic for the Larch Sawfly Pristiphora erichsonii

Publisher Website
Google Scholar
Abstract
Upon repeated subculture in media of gradually increasing pH value a strain of Bacillus cereus developed the ability to grow under strongly akaline conditions. Organisms with the highest alkali resistance could grow at pH 10-3, and stocks of intermediate resistance were also obtained. When growing on alkaline agar, resistant bacteria underwent marked morphological changes. In liquid media, the bacteria retained the ability to synthesize lecithinase. Resistance was not lost upon several transfers on a neutral medium. Resistant bacteria when growing in alkaline media caused a rapid decrease in pH value. A similar pH decrease was caused by sensitive bacteria in media of the highest degree of alkalinity in which they could grow. The decline of pH value accompanied, but did not precede, growth; acid production by the resistant bacteria does not appear to be a primary mechanism of resistance.