Interaction between lactic acid bacteria and food-borne pathogens on putrescine production in ornithine-enriched broth

Interactions of mixed cultures [lactic acid bacteria (LAB) and food-borne pathogens (FBP)] on putrescine (PUT) as well as other biogenic amines (BAs) production were investigated in ornithine-enriched broth. Significant differences in BAs production were found among the bacterial strains (P < 0.05). Conversion of ornithine into PUT by Salmonella Paratyphi A and Aeromonas hydrophila as well as Listeria monocytogenes and Staphylococcus aureus was high (>75 mg L-1), whereas other bacterial strains yielded below 50 mg L-1 of PUT. LAB strains resulted in significant reduction in PUT by Pseudomonas aeruginosa and Enterobacteriaceae, except for Escherichia coli, which was stimulated more than two-fold PUT in the presence of Lactococcus lactis subsp. lactis. Lactobacillus plantarum had generally inhibition effect on histamine (HIS) and tyramine production by FBP, whereas Lc. lactic subsp. lactic slightly stimulated HIS by E. coli and A. hydrophila. Streptococcus thermophilus resulted in 1.5-fold higher HIS formation by bacteria (10 mg L-1). Consequently, the interaction between LAB and specific FBP might result in significant inhibition of amine accumulation, if the correct LAB strains are used.