LAUSR

This study aimed to evaluate the behavior of Petrifilm™ Lactic Acid Bacteria Count Plates (PLAB) as an alternative methodology to enumerate lactic acid bacteria (LAB) in bacon. Bacon samples (n = 40) were obtained from retail sale, ten-fold diluted with buffered peptone water (BPW, 0.2% w/v) and Letheen broth, and subjected to LAB enumeration according to 4 protocols: 1) de Man Rogosa Sharpe agar (MRS), pH 5.7, 30 °C; 2) MRS, pH 5.7, 30 °C, anaerobiosis; 3) all purpose tween agar (APT), 25 °C; 4) PLAB, 30 °C. Colonies were enumerated at 24, 48 and 72h, and the results expressed as log 10 CFU/g for comparison by ANOVA and regression (p < 0.05). Further, colonies were randomly selected and characterized as LAB (Gram staining and catalase). Mean LAB counts from MRS and PLAB did not present significant differences independently of incubation time or diluent (p > 0.05), while counts in APT with BPW after 24h were significantly lower (p < 0.05). PLAB counts with BPW (24, 48, 72 h) presented significant correlation with MRS (r ranging from 0.87 to 0.89; in anaerobiosis, r ranging from 0.94 to 0.95) and APT (r ranging from 0.84 to 0.86). With Letheen, PLAB (24, 48, 72h) presented significant correlation with MRS (r ranging from 0.92 to 0.94; in anaerobiosis, r ranging from 0.93 to 0.96) and APT (r ranging from 0.77 to 0.79). A total of 1,032 from 1,063 (97%) colonies was characterized as LAB. Based on the obtained results, PLAB can be considered as an alternative tool for enumerating LAB in bacon, with reliable results even after 24 h of incubation.