Effects of NaCl, lactose and availability of oxygen on tyramine production by the Enterococcus durans CCDM 53

Combined effects of concentration of lactose (5 g/L), NaCl (20 g/L) and aero/anaerobiosis on production of tyramine by Enterococcus durans CCDM 53 were subjected to a study. The influence of the above factors and temperature of cultivation (10 ± 1 °C) was monitored under conditions applied in real technological processes of cheese production; the enterococci act as non-starter lactic acid bacteria. Production of tyramine by E. durans CCDM 53 was mainly influenced by both concentration of NaCl in cultivation medium and presence/absence of oxygen in the environment. The highest production of tyramine occurred during cultivation under anaerobic conditions in the presence of the highest (20 g/L) applied concentration of NaCl and lactose (5 g/L). In the media with equal concentrations of NaCl and lactose, the concentrations of tyramine grew higher under anaerobic conditions than in aerobic environment. Regarding cultivation media with various levels of NaCl and lactose, higher production of tyramine was always found in the anaerobic environment.