Potential of the Liquid Fermentation of Fishery Waste by for Metalloprotease Production.

This study attempted to use fishery processing wastes to produce protease by TKU051. Of the tested wastes, tuna head powder (THP) was found to be the most effective carbon and nitrogen (C/N) source, and the optimal conditions were as follows: 0.811% THP, 0.052% KHPO, 0.073% MgSO, initial pH of 8.96, incubation temperature of 31.4 °C, and incubation time of 3.092 days to achieve the maximum protease activity of 2.635 ± 0.124 U/mL. A protease with a molecular weight of 29 kDa was purified and biochemically characterized. Liquid chromatography with tandem mass spectrometry analysis revealed an amino acid sequence of STVHYSTR of TKU051 protease, suggesting that the enzyme may belong to the M4 family of metalloproteases. The optimal activity of the enzyme was achieved at 60 °C and pH 8. TKU051 protease was strongly inhibited by ethylenediaminetetraacetic acid and 1,10-phenanthroline, indicating its precise metalloprotease property. TKU051 protease displayed the activity toward casein and raw fishery wastes such as tuna heads, tuna viscera, shrimp heads, and squid pens. Finally, the purified TKU051 protease could improve the free-radical scavenging activity of fishery wastes. In short, TKU051 has potential application in eco-friendly approaches to efficiently convert fishery wastes to metalloprotease.