Bacterial Antagonism between Lactobacillus casei and Staphylococcus aureus with other Bacteria on Refrigerated Broiler Carcasses

Bacterial antagonism between Lactobacillus casei as Lactic Acid Bacteria (LAB) and Staphylococcus ureus and other bacteria on poultry broiler carcasses in cold storage were studied. L. casei and S. aureus were isolated from local broiler carcasses, purified and characterized. Culture dilutions of those bacteria and a combination of equal volumes (1:1 v/v) of the two cultures containing approximately log10 6 CFU/ml were prepared. Samples of two carcasses were dipped in each of the three cultures for 20 min., in addition to the control(dipped in 0.1% peptone solution). Bacterial counts of the broilers were estimated before and after dipping and during 6 days at 4°C to observe the antagonistic effect and shelf life of carcasses. It was found that carcasses dipped in L. casei culture resulted in a significant decrease in the final counts of S.aureus from 290 initially to 10 CFU/g meat after 6 days of refrigeration storage. No significant change was observed in S.aureus count after dipping in the combined culture. The (LAB) counts increased from log 10 3.4-3.5 CFU/g meat before dipping in L.casei or in combined cultures to log 10.3 and log 8.4 after 6 days refrigeration, respectively. Enterobacteriaceae count was controlled after dipping in any of L.casei and the combined cultures. Aerobic plate count and psychrotrophs significantly increased after dipping the broilers in any of the three cultures. The result of this study indicates that the growth of the pathogenic bacteria S. aureus and to a less extent with Enterobacteriaceae were effectively controlled by L.casei on broiler carcasses. After further study, this finding may promote using this procedure to extend the shelflife of carcasses in cold storage