NUMERICAL TAXONOMY OF PSYCHROTROPHIC BACTERIA ISOLATED FROM RAW EWES MILK

A total of 204 psychrotrophic isolates from raw ewes' milk (hand and m achine milked) were identified by conventional methods. In addition, a numerical taxonomic study was conducted on 180 of these isolates and 19 reference strains. Three of the isolates were yeasts. Using identif ication schemes, 54 isolates were assigned to genera of Gram-negative aerobic rods (Pseudomonas, Acinetobacter, Flavobacterium, Moraxella an d Psychrobacter), 48 were Enterobacteriaceae (Enterobacter, Hafnia, Kl ebsiella, Citrobacter and Serratia) and one was identified as Aeromona s hydrophila. The 98 Gram-positive isolates were identified as Enteroc occus, Streptococcus, Leuconostoc, Lactococcus, Bacillus, Staphylococc us, Micrococcus, Aureobacterium, Kurthia and Microbacterium. At the 82 % similarity level (S(SM)), 18 clusters were formed. Cluster I includ ed 34 strains of Lactococcus, Streptococcus and Leuconostoc. Most of t he 35 strains in cluster II were Enterococcus. Clusters III and IV wer e identified as Kurthia and Microbacterium respectively. Cluster V was identified as Aureobacterium and cluster VI consisted of coagulase-ne gative staphylococci. Gram-negative isolates formed 12 clusters: Aerom onas (one cluster), Enterobacteriaceae (two clusters), Flavobacterium (two clusters), Pseudomonas and Psychrobacter immobilis (three cluster s) and Acinetobacter (four clusters). Non-motile variants of Ps. fragi were found. Enterococcus and Enterobacteriaceae did not have signific ant spoilage properties. As expected, Gram-negative aerobic rods were proteolytic and/or lipolytic even at low temperature. Contamination wi th certain types of psychrotrophs (Gram-negative aerobic rods and ente rococci) seemed to be associated with the milking method. The isolate of Aes. hydrophila had properties associated with virulence.