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Characterization of Bacterial Strains Isolated from a Beef Processing Plant Following Cleaning and Disinfection - Influence of Isolated Strains on Biofilm Formation by Sakaï and EDL 933 E. coli O157:H7.

The objective of this study was to investigate the effects on E. coli O157:H7 biofilm formation of bacteria isolated from meat site surfaces following cleaning and disinfection. The researchers first isolated and identified strains of the latter organisms. Samples were obtained by swabbing the surfaces of equipment or floors over areas ranging from 315 to 3,200 cm² in a slaughter hall, a meat cutting room and a meat boning room of a processing plant. The number of bacteria recovered from these surfaces ranged from < 1 to > 105 CFU/cm². In the slaughter hall, stainless steel was, in one case, one of the most contaminated materials and in other cases one of the least contaminated. The same observation was made for conveyor belts made of polyvinyl chloride in the boning room. Dominant genera in the meat plant were Staphylococcus and Bacillus which were both 34% of the isolates from the slaughter hall and 14 and 4% respectively of the isolates from the cutting room. Randomly selected isolates of each of the genera recovered from the slaughter hall were cultured with E. coli O157:H7 in meat exudate at 15°C to form dual-organism biofilms on polyurethane. In all cases but one, the isolates increased the numbers of attached E. coli O157:H7. The effects ranged from 0.37 to 1.11 for EDL 933 strain and from 0.19 to 1.38 log (CFU/cm²) for Sakaï strain. This is the first time that a resident microbiota of a meat processing plant has been shown to have a favourable effect on E. coli O157:H7 colonization of a solid surface, which is of great interest from a food safety standpoint. Int J Food Microbiol. 2009. doi:10.1016/j.ijfoodmicro.2009.04.028.

Author: Marouani-Gadri N, Augier G, Carpentier B

Published: 01/07/2009

Publication Type: Journal article

Publisher: International Journal of Food Microbiology