Identification of proteolytic pseudomonads isolated from raw milk

Proteolytic pseudomonads isolated from raw milk were classified by numerical taxonomy. Unweighted pair-group average-linkage cluster analysis was used to cluster 49 bacterial strains, of which 26 were Pseudomonas species, as described in the Bergey's Manual of Determinative Bacteriology, based on 52 characters. The milk isolates resided in two clusters; one containing Pseudomonas fluorescens and the other Pseudomonas fragi. The isolates identified with Pseudomonas fluorescens hydrolyzed milk proteins and milk fat and produced phospholipase. The Pseudomonas fragi-like isolates hydrolyzed milk proteins and milk fat but did not produce phospholipase and fluorescent pigment. The hydrolytic characteristics of milk isolates showed that the nature of the substrate and conditions under which the test was conducted were critical.