Inhibition effects of carvacrol on biogenic amines formation by common food-borne pathogens in histidine decarboxylase broth

The effect of carvacrol at different doses (0.1, 0.5 and 1 ml/100 ml) on ammonia (AMN) and biogenic amines (BAs) production by 8 food-borne pathogens (FBP), which are Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Listeria monocytogenes, Aeromonas hydrophila and Salmonella enterica serovar Paratyphi A was investigated in histidine decarboxylase broth (HDB) using HPLC method. Significance differences were found in histamine (HIS), AMN and other BAs production (P < 0.05). The highest HIS production was obtained by K. pneumoniae (2.5 mg L−1) and the lowest by E. faecalis (1.6 mg L−1). Almost all other BAs such as PUT, CAD, SPD and PHEN were formed by pathogens. The highest concentration of dopamine (DOP) was given by K. pneumoniae which produced 1004.8 mg L−1 while agmatine (AGM) was 72.5 mg L−1 for L. monocytogenes. The most significant amounts of AMN were noticed for E. coli and E. faecalis with a value of 908.19 mg L−1 and 685.46 mg L−1 respectively. Consequently, the results of this current study shows that all FBPs tested are capable of decarboxylating more than one amino acid and the effect of carvacrol on AMN and BAs formation by FBPs depends on bacterial strains as well as on carvacrol doses.