Purpose: The purpose of this experiment was to evaluate a novel (L28) Lactic Acid Bacteria and commercially available (FS56) Lactic Acid Bacteria in inhibition of Listeria monocytogenes (N1-002) on stainless steel coupons at room temperature.
Methods: Sterile stainless steel coupons (2 cm x 2 cm) were placed into 6-well plates with 2 ml of Listeria monocytogenes (log 5.00 CFU/ml) and incubated 24 hours for attachment. After the 24 hours the Listeria monocytogenes was removed and each treatment and control were added. The treatments were with strains L28, FS56 at a concentration of log 8.00 CFU/ml and the control was with a blank of de Man, Rogosa and Sharpe (MRS) Broth. The Listeria monocytogenes counts were evaluated on modified oxford agar.
Results: Our results indicate statistical differences (P<0.05) among all of our treatments and our control for counts of Listeria monocytogenes. By the end of the 24 hours the MRS control had increased to log 5.76 CFU/cm2 of Listeria monocytogenes. For the treatments, FS56 and L28 had log reduction of 3.1 CFU/cm2 and 5.76 CFU/cm2, respectively. The L28 Lactic Acid Bacteria was so effective that the Listeria monocytogenes was not detectable by means of direct agar plating method indicating it is more effective than the FS56 which is currently commercially available.
Significance: It is important to optimize these cultures for maximum impact and the new culture is more effective than the current commercial strains. LAB can be provided to processors in various forms (frozen, liquid or freeze-dried) and application can be easily implemented into current operations.