Histidine decarboxylase activity of bacteria isolated from raw and ripened Salchichon, a Spanish cured sausage

Twenty samples of raw sausages (before the ripening process) and 10 of ripened sausages of two different sizes of salchichon, one of the most-consumed ripened meat products in Spain, were microbiologically analyzed. Histidine decarboxylase activity of different isolates obtained from different culture media was evaluated by a decarboxylase agar medium and confirmed afterwards by an enzymatic method. Of the isolates obtained from raw sausages, 15.8% showed histamine-forming activity, most of them (78.1%) belonging to the Enterobacteriaceae family. Klebsiella oxytoca, Enterobacter aerogenes (one isolate), and Enterobacter cloacae (six isolates) showed a powerful histamine-forming activity, producing more than 3,000 mu g/ml. In spite of histamine-forming activity being detected in eight of ten analyzed samples of ripened sausages, only one histamine-forming bacterium, identified as Lactobacillus curvatus, was isolated; it showed an ability to form 1,994 mu g/ml of histamine in experimental conditions.