Growth of some lactic acid bacteria in milk containing sulfadiazine.

A method for testing the effect of sulfonamides on lactic acid bacteria was developed. Sulfadiazine was used as the inhibitory substance. In the study 3 lactic acid bacteria, Lactobacillus lactis, Lactobacillus helveticus and Streptococcus thermophilus, were used. Lactic acid production, pH and plate count were used as parameters when monitoring the effect of Sulfadiazine on the test organisms under anaerobic conditions in milk medium. A depressing effects due to Sulfadiazine on each of the test microbes could be demonstrated by all of the parameters used. Measurement of the inhibition in lactic acid production using Streptococcus thermophilus as test organism should be used when rapid determination of Sulfadiazine residues in milk is preferred.