Abstract #M140

# M140
Effect of bio-protective lactic acid bacteria cultures on Lactobacillus wasatchensis.
A. Lavigne1, S. Smith1, C. Oberg*1, I. Bowen2, D. McMahon2, 1Weber State University, Ogden, UT, 2Utah State University, Logan, UT.

The nonstarter lactic acid bacteria (NSLAB) Lactobacillus wasatchensis can cause late gassy defect when it grows to high numbers during Cheddar cheese storage. A potential strategy for preventing such growth is incorporation of specific lactic acid bacteria strains (termed bio-protective LAB) into the cheese during manufacture, which may specifically inhibit growth of Lb. wasatchensis. Determination of inhibition by common NSLAB lactobacilli and potential bio-protective LAB (BPLAB) strains against Lb. wasatchensis was done using the spot test along with the agar flip method. MRS agar supplemented with 1.5% ribose (MRS-R) was inoculated with each NSLAB or bio-protective LAB using the spread plate method and incubated anaerobically at 25°C for 48 or 72 h. Inoculated agar was then flipped over and either Lb. wasatchensis WDC04 or CGL04 swabbed on the newly exposed surface with anaerobic incubation at 25°C for up to 72 h. None of the BPLAB strains produced any more inhibition after 48 h than the general competitive inhibition caused by the NSLAB cultures Lactobacillus brevis or Lactobacillus fermentum LF7469. When incubation time was extended to 72 h before challenge, BPLAB P200 showed the largest inhibition zones for both Lb. wasatchensis WDC04 and CGL04. The next inhibitory BPLAB was LB-3 with the NSLAB, Lb. fermentum LF7469, also producing a large inhibition zone. To test for bacteriocin production by the BPLAB, a paper disc assay test was performed using cell free extracts. Results confirmed several BPLAB strains produced a bacteriocin, showing a very small zone of inhibition for Lb. wasatchensis around the paper disc. Examining the antagonism between bio-protective cultures and NSLABs for Lb. wasatchensis strains allows for selection of lactic acid bacteria strains that could inhibit this problematic bacterium during cheese ripening.

Key Words: lactic acid bacteria, Lactobacillus, gassy defect