COMPATIBILITY AMONG PATOGENIC INDICATOR MICRORGANISM STRAINS USED IN DECONTAMINATION TESTS OF ASSAI BERRIES

This work was designed to verify the relation of efficacy of sanitizing processes in assai berries and compatibility among the strains from the same microorganism, avoiding erroneous interpretation of the results. In this sense, this study evaluated strains of pathogenic indicator microorganisms that have an antagonistic effect on the ability to inhibit their growth. Five strains of Salmonella spp. (ATCC10708, ATCC13076, ATCC13311, ATCC14028 and Salmonella Brazil from assai), Listeria monocytogenes (1/2a CLIST0305, 4b CLIST0586, 1/2a CLIST2035 ATCC19111, 1/2b CLIST2169 and 4b CLIST3436 SCOTT A) and Escherichia coli (ATCC8739, ATCC10799, ATCC11229, ATCC25922 and ATCC43893) were used. Each of the five strains from each test microorganism was activated from the stock cultures previously elaborated for three consecutive days, in a test tube containing 5 mL of BHI broth (Oxoid) and was incubated at 37 °C ± 0.5 for 24 h, observing the growth of the cells by turbidity of the medium. They were collected in a 50 mL Falcon tube and centrifuged three times at 2,000 x g for 15 min at room temperature (CT-500), then washed and re-suspended in 0.1% peptone water (Difco). Strains were cross-stained in TSA (Difco) and incubated for 24h at 37 °C ± 0.5. The observation of inhibition of the strains was assessed by the colony growth on the junctions of the striae. Cross-inhibition tests did not detect zone of growth inhibition among all strains of the three microorganism’s components of the assays. The mix of strains that composed the respective inoculants of each microorganism did not present any strain interaction, which could interfere in the analysis of reduction population after the application of decontamination treatments in assai fruits.