An improved screening plate method for the detection of amino acid decarboxylase-positive
microorganisms (especially lactic acid bacteria) was developed. The suitability and
detection level of the designed medium were quantitatively evaluated by confirmation
of amine-forming capacity using an HPLC procedure. The potential to produce the biogenic
amines (BA) tyramine, histamine, putrescine, and cadaverine, was investigated in a
wide number of lactic acid bacteria (LAB) of different origin, including starter cultures,
protective cultures, type strains and strains isolated from different food products.
Also, several strains of Enterobacteriaceae were examined. Modifications to previously
described methods included lowering glucose and sodium chloride concentrations, and
increasing the buffer effect with calcium carbonate and potassium phosphate. In addition,
pyridoxal-5-phosphate was included as a codecarboxylase factor for its enhancing effect
on the amino acid decarboxylase activity. The screening plate method showed a good
correlation with the chemical analysis and due to its simplicity it is presented as
a suitable and sensitive method to investigate the capacity of biogenic amine production
by LAB. Tyramine was the main amine formed by the LAB strains investigated. Enterococci,
carnobacteria and some strains of lactobacilli, particularly of Lb. curvatus. Lb.
brevis and Lb. buchneri, were the most intensive tyramine formers. Several strains
of lactobacilli, Leuconostoc spp., Weissella spp. and pediococci did not show any
potential to produce amines. Enterobacteriaceae were associated with cadaverine and
putrescine formation. No significant histamine production could be detected for any
of the strains tested.