Estimation of Bacterial Concentrations in Commercial Foods by Measuring ATP Changes during Incubation.

Abstract

Recently we have developed new kinetic methods of bacterial cell estimation in food products by measurement of the increase in bacterial adenosine-triphosphate (ATP) content during incubation using a conventional firefly luminometer [Fujikawa and Morozumi: Jpn. J. Food Hyg. (2002)]. The methods were the end point method and the delay method. We, in this study, evaluated these methods for bacterial concentration estimation in commercial foods. The methods were successfully applied to food products inoculated with Escherichia coli or Staphylococcus aureus. The methods were then used to estimate bacterial concentrations in commercial foods. For estimation, the kinetic parameter values were determined first from the data of bacterial strains studied previously. The bacterial concentrations estimated with these parameter values were slightly smaller than the measured concentrations for most of the food samples. The parameter values obtained with the least-squares method gave better estimations in both methods. The delay method predicted the bacterial concentrations in food products better than the end point method. This study showed that with appropriate parameter values, these methods could be useful tools for bacterial concentration estimation of commercial foods.

Variation in detection limits between bacterial growth phases and precision of an ATP bioluminescence system

“…The concentration of ATP per cell varies between bacterial species, from cell to cell within the same species, and at different points in the bacterial life cycle. The life cycle, or growth curve, consists of lag, log, stationary and death phases (Fujikawa and Morozumi , , ; Shama and Malik ). The length of each phase is dependent on the specific organism and the medium used for growth.…”

Firefly Luciferase Enzyme Fragment Complementation for Imaging in Cells and Living Animals

“…Firefly luciferase is one among many of the sensitive luciferases and is widely used by researchers to identify different biological events of cells in culture and in living small animals, and it is also used by public health researchers for the detection of food contamination. [1][2][3] The gene encoding firefly luciferase, cloned in 1985 from the North American firefly, Photinus pyralis, is now emerging as the gene of choice for in vivo and in vitro reporting of transcriptional activity in eukaryotic cells. 4 Reporter genes encoding for proteins with optical signatures, either fluorescent or bioluminescent, are a low-cost alternative for realtime analysis of gene expression in small-animal models.…”

“…[1][2][3] The gene encoding firefly luciferase, cloned in 1985 from the North American firefly, Photinus pyralis, is now emerging as the gene of choice for in vivo and in vitro reporting of transcriptional activity in eukaryotic cells. 4 Reporter genes encoding for proteins with optical signatures, either fluorescent or bioluminescent, are a low-cost alternative for realtime analysis of gene expression in small-animal models.…”

Rapid Enumeration of Microbial Cells in Solubilized Soymilk Using an Automatic Cell Counting System with LED Illumination

“…Therefore, a simple, rapid, and accurate detection method is desirable. Several non-culture methods have been used for the rapid detection of bacteria in food (Fujikawa and Morozuki, 2003;Gracias and Mckillip, 2004;Kawasaki et al, 2004;Kawasaki et al, 2007;Masuda-Nishimura et al, 2000;Miyamoto et al, 1998). PCR is a useful technique because of its high sensitivity.…”