EFFECT OF DIACETYL ON GROWTH-RATE OF SALMONELLA-TYPHIMURIUM DETERMINED FROM DETECTION TIMES MEASURED IN A MICRO-WELL PLATE PHOTOMETER

The determination of growth rates from detection rimes measured in an automatic micro-well plate photometer is described With triplicate cul tures of each of four different inoculum concentrations, the growth ra te of Salmonella typhimurium was determined with a coefficient of vari ation of 2%. The minimum inhibitory concentration (MIC) of diacetyl fo r Salmonella typhimurium at 30 degrees C, pH 5.0-6.0, was 1.4 mmol l(- 1) when the initial inoculum was 10(4) cfu ml(-1): but was lower for a smaller inoculum. Sublethal diacetyl concentrations were found to red uce the specific growth rate of Salmonella typhimurium pH values over the range pH 5.0-6.5 had little effect on the antimicrobial activity o f diacetyl. Crown Copyright (C) 1996 Published by Elsevier Science Ltd .