Identification, biochemical and technological properties of Enterococcus species isolated from raw milk and traditional dairy products

Abstract

Introduction. The purpose of research was isolation and identification of Enterococcus species from raw milk and traditional dairy products and their biochemical properties were examined. Some biochemical and technological properties of the strains were determined. Materials and methods. Raw milk and some dairy product samples (Izmir Tulum cheese, Koy cheese, White cheese, butter, Ezine cheese, kefir grain, kefir drink, Armola, Tire Camur cheese, Herby cheese, Goat cheese and Cecil cheese) were collected in different regions of Turkey and samples were inoculated in Kanamycin Aesculin Azide Agar, Slanetz Bartley and M-17 Agar media and Enterococcus spp. were isolated. Acidification properties, exopolysaccharide (EPS) production, lipolytic and proteolytic activity, and decarboxylation activity of Enterococcus strains, which were diagnosed phenotypically and biochemically with different techniques were investigated. Results and discussion. 167 lactic acid bacteria were identified after Gram staining and catalase tests. Due to the analysis, 122 of these isolates identified as Enterococcus faecium, 18 as Enterococcus durans, 17 as Enterococcus faecalis, 8 as Enterococcus faecium var. and 2 as Enterococcus hirae. Some biochemical and technological properties of these species were studied. It was determined that E. faecium and E. faecalis strains produced higher acidity compared to E. durans and E. hirae, a total of 19 strains were capable of producing EPS, while 9 strains showed poor EPS production. Also, it was performed 17 E. faecium, 2 E. faecalis, 1 E. durans and 1 E. hirae strains showed lipolytic activity and 95 E. faecium, 12 E. durans, 5 E. faecalis var., 3 E. faecalis and 2 E. hirae decarboxylated to lysine and ornithine amino acids. It was observed that Enterococcus spp. isolated from raw milk and traditional dairy products showed differences especially technological characteristics according to the source, species and strain. Conclusions. Raw milk and dairy products are important source for isolation of enterococci species. The characteristics of Enterococcus species such as acidification, exopolysaccharide production ability, proteolytic and lipolytic activity, decarboxylase activity differed by species and strain.