Purpose: The objective of this study was to evaluate the performance of the Aerobic Procedure for Lactic Acid Bacteria with 3M™ Petrifilm™ Aerobic Count Plates compared to the Agar method using acidified MRS (deMan, Rogosa and Sharpe) referred in the Compendium of Method for the Microbiological Examination of Foods.
Methods: A total of 53 samples from a mix of turkey and pork ham were artificially inoculated with LAB strains commonly found in these products (Leuconostoc mesenteroides and a mixture of Lactococcus lactis spp lactis and Lactobacillus brevis) at a medium level of 50-100 CFU/plate. Samples were analyzed in duplicate by standard plate count method using acidified MRS agar to pH 5.5 ± 1 and the Aerobic Procedure for LAB that utilizes the Petrifilm Aerobic Count Plate supplemented with MRS medium and a pH indicator to help identify and enumerate lactic acid bacteria.
Results: The counts from both methods were converted to log values and averaged. A paired t-test for two sample means was calculated to analyze statistical differences. Results do not show any significant differences (P = 0.56) between the methods, the Pearson correlation coefficient (r) was also determined showing a positive correlation (0.96).
Significance: Results shown that the Aerobic Procedure for the detection and enumeration of LAB is a reliable and easy method that reduces time for confirmation and cost of sample preparation by eliminating the materials needed to create an anaerobic environment.