Bacterial decarboxylases and aminotransferases may be involved in the production of flavour or off-flavour compounds from aromatic amino acids during cheese ripening. Transamination is one of the first steps in amino acid catabolism for both lactococci and lactobacilli (Gao et al. 1997; Klein et al. 2001). Biologically active amines, produced by decarboxylation, such as tyramine, phenylethylamine, tryptamine, histamine, cadaverine and putrescine, known as biogenic amines, have been found in cheese and can cause migraine and hypertension in susceptible consumers (McSweeney & Sousa, 2000).