Growth and survival of uninjured and sublethally heat-injured Escherichia coli O157:H7 on beef extract medium as influenced by package atmosphere and storage temperature

Abstract

The effect of atmospheric composition and storage temperature on growth and survival of uninjured and sublethally heat-injured Escherichia coli O157:H7, inoculated onto brain heart infusion agar containing 0.3% beef extract (BEM), was determined. BEM plates were packaged in barrier bags in air, 100% CO2, 100% N2, 20% CO2: 80% N2, and vacuum and were stored at 4, 10, and 37 degrees C for up to 20 days. Package atmosphere and inoculum status (i.e., uninjured or heat-injured) influenced (P < 0.01) growth and survival of E. coli O157:H7 stored at all test temperatures. Growth of heat-injured E. coli O157:H7 was slower (P < 0.01) than uninjured E. coli O157:H7 stored at 37 degrees C. At 37 degrees C, uninjured E. coli O157:H7 reached stationary phase growth earlier than heat-injured populations. Uninjured E. coli O157:H7 grew during 10 days of storage at 10 degrees C, while heat-injured populations declined during 20 days of storage at 10 degrees C. Uninjured E. coli O157:H7 stored at 10 degrees C reached stationary phase growth within approximately 10 days in all packaging atmospheres except CO2. Populations of uninjured and heat-injured E. coli O157:H7 declined throughout storage for 20 days at 4 degrees C. Survival of uninjured populations stored at 4 degrees C, as well as heat-injured populations stored at 4 and 10 degrees C, was enhanced in CO2 atmosphere. Survival of heat-injured E. coli O157:H7 at 4 and 10 degrees C was not different (P > 0.05). Uninjured and heat-injured E. coli O157:H7 are able to survive at low temperatures in the modified atmospheres used in this study.

Heat inactivation data for Mycobacterium avium subsp. paratuberculosis: implications for interpretation

“…Not only the growth conditions prior to heat treatment, but also those after heating will in¯uence survival of bacterial cells. After heat treatment many cells will be sublethally injured, as can be observed by the substantial delay in detecting growth of heat-treated bacterial cells compared with unheated cells (D'Aoust 1978;Meylan et al 1996;Keswani and Frank 1998;Semanchek et al 1999). Hence, recovery of injured MAP cells in an appropriate medium after heat treatment is very important and may in¯uence MAP survival counts (Damato and Collins 1990;Keswani and Frank 1998).…”

“…After heat treatment many cells will be sublethally injured, as can be observed by the substantial delay in detecting growth of heat‐treated bacterial cells compared with unheated cells (D’Aoust 1978; Meylan et al . 1996; Keswani and Frank 1998; Semanchek et al . 1999).…”

A strictly anaerobic recovery and enrichment system for improved detection of heat-injured Escherichia coli O157:H7

“…E.coli O157:H7 can also survive well during frozen storage of beef, chicken, and water at temperatures as low as -80°C and at -20°C for as long as 9 months . In addition, various studies have demonstrated that the organism is also resistant to nitrate, sodium chloride, alkaline environments, and modified atmosphere (Glass et al, 1992;Semanchek et al, 1999).…”

Estudio De La Calidad De Naranjas Y Mandarinas Mínimamente Procesadas. Influencia De Variables Del Proceso.

“…Listeria monocytogenes, E. coli O157: H7 y Aeromonas hydrophila mostraron una menor capacidad de crecer y sobrevivir en condiciones adversas de almacenamiento cuando fueron previamente tratadas con un tratamiento térmico (Williams y Golden, 2001;Semanchek et al, 1999;Golden et al, 1989), revelando que un tratamiento térmico leve puede ser usado en combinación con otros factores de conservación para el control de patógenos que se transmiten por alimentos en frutas y verduras.…”