Hydrogen Peroxide Formation and Catalase Activity in the Lactic Acid Bacteria

Some lactic acid bacteria formed detectable H2O2 and some did not, regardless of their preference or requirement for aerobic or anaerobic conditions. Whether or not H2O2 was formed depended in some instances on the substrate used as energy source. Two H2O2-splitting activities were encountered though never in the same organism. One, named pseudo-catalase activity, was insensitive to 0·01 m-azide or 0∙01 m-cyanide and appeared to be the action of an acid-sensitive non-haem-containing enzyme detectable in some leuconostocs and pediococci when grown in media containing a low concentration of glucose. The second, named catalase activity, was detected in a number of lactobacilli, leuconostocs, streptococci and pediococci grown on media containing haematin or heated blood; presumably these organisms are able to synthesize the apoenzyme but not the prosthetic group of catalase. This activity was inhibited by 0∙01 m-azide or 0∙01 m-cyanide; it was not acid-sensitive. There was little correlation between H2O2-splitting activity and the preference or requirement of the organisms for aerobic or anaerobic conditions, or between H2O2-splitting activity and H2O2 formation. Of a few organisms examined, some appeared capable of forming cytochromes when grown in media containing heated blood. One showed traces of a cytochrome whether grown in the presence or absence of heated blood.