Atlantic mackerel was purchased from a local retailer (Wageningen, The Netherlands) and ground
in a meat grinder with a 4-mm die. Each batch of silage consisted of 100 g of ground mackerel to which 100 ml of an aqueous solution containing 2.4g l sucrose, 0.4 g l NaCl and 0.2 g l histamine dihydrochloride were added. The resulting mixture was thoroughly homogenised using a spatula and 2%(v/w) of an 18-h MRS broth (Oxoid, CM 359,Basingstoke, UK) culture of the designated LAB isolate was added. For the DAO experiment, 10 780 21 units kg DAO were added as well. Cultures 15.18 and 15.36 (both Lb. sakei) were used as an inoculum in the fish experiment, since they had been found to degrade histamine in the model system. Fish slurries
with added DAO were inoculated with a non-his-tamine degrading bacterium (Lb. curvatus 22.24). A control slurry was inoculated with isolate 22.24 only,to determine histamine autodegradation during ensil-