Recovery of sublethally heat-injured Salmonella typhimurium on supplemented plating media.

Abstract

The efficacy of 32 additives to Levine eosin-methylene blue-salts agar medium (EMBS) for the recovery of sublethally heat-injured Salmonella typhimurium was evaluated. In order of decreasing effectiveness, lactate, mannitol, and alpha-glycerophosphate mediated 90% or more recovery of injured cells; similar levels of recovery were obtained on EMBS supplemented with 1% (wt/vol) tryptic soy broth, protease peptone, or plate count agar. Other additives showed little or no capacity for repair or strongly inhibited heated and nonheated cell suspensions. Conditions of growth and storage before heat treatment were also found to markedly affect susceptibility to heat injury.