Investigation of In-Vitro antimicrobial effeccts of organic acides on the biogenic amine production and bacterial growth

In this study, the effects of tree different organic acids (propionic, acetic and formic acid) at doses of 0.5 % on growth and biogenic amine production of eight reference bacterial strains(Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Aeromonas hydrophila, Salmonella Paratyphi A, Campylobacter jejuni and Yersinia enterocolitica) and five lactic acid bacteria (Lactococcus lactic subsp. lactic, Lactobacillus plantarum, Streptococcus thermophilus, Leuconostoc mesenteroides subsp. cremoris and Pediococcus acidolactici) were investigated in two different amino acid (histidine and tyrosine) decarboxylase broth. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of organic acids against test strains were determined by using broth microdilution method. Among organic acids tested, formic acid showed the highest antimicrobial activity, followed by propionic acid. E. coli, E. faecalis, S. Paratyphi A and S. aureus were the most susceptible strains against formic acid, with MIC value of 0.78 mg/mL. MBC of reference strains was generally above 50 mg/mL, whilst lactic acid bacteria had 6.52 mg/mL of MBC. The lowest bacterial load in amino acid decarboxylase broth was observed by Ps. acidolactici (5.38 log cfu/mL) in the presence of formic acid. The main amines produced by bacteria were dopamine, agmatine, putrescine and tyramine. In histidine decarboxylase broth, histamine production was in range from 0.12 mg/L (S. Paratyphi A) to 28.56 mg/L (A. hydrophila), although the highest histamine production by lactic acid bacteria was found as 2.38 mg/L (Lb. plantarum). In tyrosine decarboxylase broth, the highest tyramine production was 578.22 mg/L for E. coli as references strains and 22.05 mg/L for Lac. subsp. lactis as lactic acid bacteria. The effect of organic acids on biogenic amine production varied depending on amino acid decarboxylase broth, type of acid, bacterial strains and specific biogenic amines.