Selected microbial consortium of raw and digested pig slurry and its susceptibility to enterocins

Abstract

A consortium of bacterial genera from raw and digested pig slurry (pig farm at Figa, Slovakia; input and output samples) was counted from February to October 2000. The total counts of enterococci and staphylococci were well-balanced in input samples, with visible reduction of cells in May (3.22 and/or 4.21 log c.f.u./ml). Among organisms important from a sanitary perspective only a slight reduction after standard slurry treatment was found between input and output samples (2.0 log cycles), with no effect in April and May. However, their counts were high (8.1–9.01 log c.f.u./ml). Yersinia sp. were detected in rather high counts (6.47; 6.39 log c.f.u./ml). But these species, as well as pseudomonads and Aeromonas sp. were very effectively reduced by standard slurry treatment. Enterocins (CCM4231, V24 and EC24) produced by our own isolates of enterococci were used to determine the susceptibility of selected microbial strains from slurry to those enterocins. For quantifying the inhibitory activity of enterocins, the titre (expressed in activity-arbitrary units [AU/ml]), corresponding to the reciprocal of the highest dilution showing a distinct inhibition zone of the indicator, was determined. Under the conditions used, enterocins used were active against the selected microbial consortium by activity from 100 up to 800 AU/ml. Moreover, enterocin V24 reduced the growth of Enterobacter cloacae ECL751 as well as Pseudomonas sp. minimally with differences of 1. 54 and 2.2 log cycles.