E. Tsakalidou

Heterogeneity of Lactobacillus plantarum isolates from feta cheese throughout ripening.

Thirty‐two Lactobacillus plantarum strains isolated from Feta cheese throughout ripening were studied for their phenotypic characteristics, protein profile of cell‐free extracts, enzyme profiles, plasmid profiles, proteolytic and acidifying abilities and ability to grow at low pH and in the presence of bile. Results showed that some biotechnologically important characteristics, such as acidifying and proteolytic activities, can differ between strains. In addition, different plasmid profiles suggest the presence of different Lact. plantarum strains in Feta cheese throughout ripening. The results suggest the possibility of choosing strains with specific biotechnologically interesting properties.

Biochemical properties of Streptococcus macedonicus strains isolated from Greek Kasseri cheese

A total of 32 Streptococcus macedonicus strains, isolated from Greek Kasseri cheese, were screened for biochemical properties of technological importance in milk fermentation processing, such as acid production, proteolytic and lipolytic activity, citrate metabolism, exopolysaccharide production, antimicrobial activity and biogenic amines production. All strains were found to be moderate acidifiers in milk. Only four strains could hydrolyse milk casein, while 11 strains showed lipolytic activity against tributyrin. Using amino acid derivatives of 4‐nitroaniline as substrates, the highest peptidase activities were determined against phenylalanine‐ and glycine‐proline‐4‐nitroanilide. Using fatty acid derivatives of 4‐nitrophenol, it was shown that all strains exhibited esterase activities up to caprylate, with highest values against butyrate and caproate. Only one showed activity up to palmitate; this was also the most active strain against tributyrin. Five of the 32 strains could metabolize citrate but none of them produced exopolysaccharides. Nine strains displayed antimicrobial activity towards Clostridium tyrobutyricum, while no antimicrobial activity was detected against Listeria innocua and Propionibacterium freudenreichii subsp. shermanii. Finally, none was able to decarboxylize ornithine, histidine or lysine, and only four strains produced tyramine from tyrosine.

Diversity of Shewanella population in fish Sparus aurata harvested in the Aegean Sea

Aims:  To study the diversity of Shewanella population in Sparus aurata fish harvested in the Aegean Sea, as well as to elucidate the influence of fish storage conditions on the selection in Shewanella strains.

Cloning and sequencing of the gene encoding X-prolyl-dipeptidyl aminopeptidase (PepX) from Streptococcus thermophilus strain ACA-DC 4

Aims:  To clone and sequence the pepX gene from Streptococcus thermophilus.