Abstract: Sterile turbot fillets were inoculated with Shewanella putrefaciens SP22 in pure culture or in co-culture with Hafnia alvei Ha-01 and then stored at 4 ℃. The microbial and physicochemical indexes (including total viable count (TVC), total volatile basic nitrogen (TVB-N) value, K value, Ca2+-ATPase and ultrastructural change) were measured after different periods of storage. The aim was to evaluate the spoilage potential of the pure and mixed cultures on turbot fillets. The results indicated that the TVC, TVB-N and K values of inoculated fish fillets increased significantly faster than those of the uninoculated control, and the samples inoculated with the co-culture showed the fastest increase. The Ca2+-ATPase activity of the inoculated samples decreased significantly faster than that of the control group and the co-culture group showed the fastest decrease. The rate of degradation of muscle proteins in the inoculated samples was clearly faster than that of the control group as observed under scanning electron microscope. In conclusion, Shewanella putrefaciens SP22 could cause turbot spoilage, and when co-cultured with Hafnia alvei Ha-01, it could lead to turbot fillet spoilage obviously during refrigerated storage.

Key words: Scophthalmus maximus, Shewanella putrefaciens, Hafnia alvei, spoilage potential