EFFECT OF OXYRASETM ENZYME ON LISTERIA MONOCYTOGENES AND OTHER FACULTATIVE ANAEROBES1

Abstract

ABSTRACT The use of an oxygen‐reducing membrane fraction to stimulate growth of some anaerobic bacteria has been reported. In this study, stimulated recovery of Escherichia coli 0157:H7, Salmonella typhimurium, Streptococcus faecalis, and heat‐injured Listeria monocytogenes was achieved by using broth media supplemented with OxyraseTM (membrane‐bound enzyme system derived from E. coli). The OxyraseTMenzyme allowed rapid growth of these facultatively anaerobic organisms in a nonselective broth. The activity of OxyraseTMin four different selective enrichment broths to support growth of L. monocytogenes also was evaluated. Among tested broths, FDA‐approved Listeria Enrichment Broth containing OxyraseTMwas found to be substantially superior for facilitating the growth of L. monocytogenes. OxyraseTMpromoted a significantly greater number of L. monocytogenes than commonly used but nonspecific reducing agents, such as L‐cysteine HCl and sodium thioglycolate. These findings indicated that all organisms tested can be grown well in liquid media using the oxygen‐consuming membrane fragments to achieve and maintain oxygen‐limited conditions. The Oxyrase TM enzyme system has potential applications in some selective media and other diagnostic tests specified for rapid detection of these facultatively anaerobic pathogens.