SELECTIVE ACTION OF INHIBITORS USED IN DIFFERENT CULTURE MEDIA ON THECOMPETITIVE MICROFLORA OF SALMONELLA

The action of 12 inhibitors employed in the culture media used to dete ct the presence of Salmonella in food on 24 bacterial strains includin g contaminating Gram-positive bacteria common in water and food, Gram- negative bacteria, especially Enterobacteriaceae and Pseudomonadaceae, which are components of the competitive microflora, and six Salmonell a serotypes was tested. Two liquid culture media (AR 5 and AE 1) were used. Series of tubes containing increasing concentrations of each inh ibitor were inoculated with the test strains and incubated at 37 degre es C until growth was verified spectrophotometrically (24-48 h). The r esults showed that the inhibitors were effective against the Gram-posi tive contaminating microflora. They did not preferentially inhibit the competitive microflora of Salmonella, chiefly Enterobacteriaceae, and were ineffective against the Pseudomonas strains, which can tolerate concentrations higher than those customarily employed in culture media .