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 cultures of each of four different inoculum concentrations, the growth rate of Salmonella typhimurium was determined with a coefficient of variation of 2%. The minimum inhibitory concentration (MIC) of diacetyl for 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 reduce the specific growth rate of Salmonella typhimurium pH values over the range pH 5.0-6.5 had little effect on the antimicrobial activity of diacetyl. Crown Copyright (C) 1996 Published by Elsevier Science Ltd.