Inhibitory properties of Enterococcus spp. isolated from faeces of healthy dogs.

FERNÁNDEZ JURI M.G. ,; MUZZOLÓN J.A.; DALCERO A.M; MAGNOLI C.E,

JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART B - PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2013 vol. 48 p. 983 - 992

0360-1234

The aim of the present study was to evaluate the inhibitory effect of Enterococcus faecium strains isolated from faeces of healthy dogs and their cell-free supernatant (CFS) on the growth of potentially pathogenic bacteria isolated from clinical cases and aflatoxigenic Aspergillus section Flavi and the consequent aflatoxin B1 (AFB1) production on in vitro assays. Nine strains of E. faecium previously isolated from fresh faeces from healthy dogs were tested for inhibitory properties against potentially pathogenic Gram negative and positive bacteria by the cross-strake method. A first approach of the nature of the inhibition was determined by the well-diffusion test using non treated and treated CFS of E. Faecium strains. The growth and aflatoxin B1 production inhibition was also assayed for Aspergillus spp. by the well-diffusion test using only non treated CFS. Results obtained from the cross-strake assay showed that E. faecium MF1, GJ18 and GJ40 presented the major inhibitory activity against all pathogenic strains assayed; E. faecium GJ40 produced the larger inhibitory zones (26-27 mm). Well-diffusion test results showed that the majority of the enterococci strains CFS had antimicrobial activity against the pathogenic microorganisms, observed as a formation of an inhibition zone around the wells. In general, Gram positive indicators were lesser inhibited by enterococci CFS than Gram negative indicators. None of the enterococci cell-free supernatant assayed inhibited S. aureus growth. Cell-free supernatant of E. faecium GJ40 was the one that produced the largest inhibition zones (14 to 21 mm) in the majority of the indicator microorganisms assayed. All supernatants treated with 10 N NaOH (pH6) showed no inhibitory effect on the indicator strain assayed. Respect to fungal inhibition, any of the non treated CFS assayed significantly inhibited the Aspergillus strains growth. But, in general, in the CFS exposure with A. flavus and A. parasiticus, all CFS reduced AFB1 production from 8 to 87%. The results demonstrate that enterococci isolated from healthy dog feaces produce substances with the capacity to inhibit some potential pathogenic bacteria growth that are animal feed contaminants and potentially food intoxication agents ,in the same way, the capacity of inhibiting or reducing the AFB1 production in vitro.