Survival of escherichia coli o157:h7 co-cultured with different levels of pseudomonas fluorescens and lactobacillus plantarum on fresh beef

Abstract

The purpose of this study was to investigate the effect of different levels of Pseudomonas fluorescens (10 2 and 10 6 log 10 cfu/ml) and Lactobacillus plantarum (10 2 and 10 4 log 10 cfu/ml) on the growth of Escherichia coli O157:H7 on beef loins. Beef loins inoculated with E. coli O157:H7 and P. fluorescens were aerobically stored for 7 days at 4 ºC, while those inoculated with E. coli O157:H7 and L. plantarum were vacuum packaged and stored for 8 weeks at 4 ºC. Aerobic Plate Counts (APC), E. coli O157:H7 and either P.fluorescens or L. plantarum counts were determined at different storage intervals. For the aerobically packaged beef loins, E. coli O157:H7 was detected throughout the 7 day storage period regardless of the P.fluorescens level in the inoculum. For the vacuum packaged beef loins, similar inoculum levels of E. coli O157:H7 and L. plantarum allowed E. coli O157:H7 to survive until week 5 of storage, while a higher inoculum level of L. plantarum inhibited E. coli O157:H7 from week 3. Once fresh beef has been contaminated with E. coli O157:H7, the level of P. fluorescens in the background flora does not inhibit its survival and growth. However, under vacuum storage, the application of L. plantarum as a biopreservative inhibits the survival of E. coli O157:H7 on beef. The higher the level of L. plantarum in the system, the earlier the onset of the inhibition. Farmers and abattoirs have to strengthen preventive strategies to eliminate contamination of beef carcasses with E. coli O157:H7.

Carnobacterium maltaromaticum as bioprotective culture against spoilage bacteria in ground meat and cooked ham

“…Besides, in our study, the inhibitory effect of C. maltaromaticum on Enterobacteriaceae did not seem to be influenced by the presence of both inoculated P. fluorescens or B. thermosphacta. Tshabalala, de Kock, and Buys (2012) also report that other LAB species (Lactiplantibacillus plantarum) could impact the growth of Escherichia coli O157:H7 in fresh beef stored aerobically and under vacuum storage, which was not affected by P. fluorescens, regardless of the inoculation level or storage time. Inoculated B. thermosphacta population was also inhibited by Carnobacterium both in ground beef and in cooked ham.…”

Effects of Lactobacillus plantarum 15-1 and fructooligosaccharide on the response of broilers to pathogenic Escherichia coli O78 challenge

“…Experiment in vitro [10] found that lactobacilli inhibited the TLR4 inflammatory signaling induced by enterotoxigenic Escherichia coli via modulation of the inflammation and involvement of TLR2 in human intestinal Caco-2/TC7 cells and intestinal explants. Lactobacillus Plantarum inhibited the growth of Escherichia coli O157:H7 in vitro [11]. Moreover, Lactobacillus Plantarum possesses the ability to improve the growth performance, reducing Enterobacteriaceae , increasing the population of Lactobacillus , the villi height of the small intestine and the concentration of volatile fatty acids in faeces of the broiler [12].…”