Bactérias ácido láticas com atividade antagonista a Listeria monocytogenese Escherichia coli em leite cru produzido no Estado de Pernambuco

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Lactic Acid Bacteria (LAB) are microorganisms naturally found in several foods that have an important role in controlling pathogenic microorganisms in food since they are able to produce numerous substances with antimicrobial antagonic potential, that affect microorganisms such a Listeria monocytogenes and Escherichia coli. Aiming to verify the presence of L. monocytogenes, enumerate E. coli and LAB, and verify the antagonic activity of isolated LAB against L. monocytogenes and E. coli, samples of raw milk were collected from 45 milk farms from Agreste region of Pernambuco. For L. monocytogenes detection VIDAS Listeria (bioMeriex) system was use and for E. coli enumeration PetrifilmTM EC (3M) was use and incubated at 35oC for 48 hours. For LAB counting samples were diluted in MRS broth and distributed PetrifilmTM AC (3M) plates, incubated for 72 hours on microaerophilic conditions. Pathogens antagonism was determined through spot-on-the-lawn modified methodology using L. monocytogenes ATCC 7644 and E. coli ATCC 25922 strains. In order to do that 671 LAB cultures isolated from the 45 samples were selected. L. monocytogenes was not detected in any milk sample and E. coli counting varied from <1, 0 x 103 to 1,3 x 105 CFU/mL. LAB counting varied from 11,1 x 104 to 9,9 x 106 CFU/mL. Cultures tested for antagonic capacity against L. monocytogenes, were antagonic in 549 (81,8%) samples, from which 410 (61,2%) showed total inhibition and 139 (20,7%) partial inhibition. Concerning E. Coli, 258 (38.5) cultures showed antagonist activity, all with partial inhibition. High countings of E. coli found constitute a risk to health and indicate potential contamination by other enteropathogens. Elevated frequency of LAB antagonic to L. monocytogenes can be responsible for the absence of this pathogen in milk samples studied.

ASSUNTO(S)

bactérias produtoras de ácido láctico leite - bacteriologia listeria lactic acid bacteria escherichia coli milk - bacteriology

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