Isolation of a new toxic protease from a strain of Aeromonas salmonicida subspecies achromogenes

A new toxic protease was isolated from Aeromonas salrnonicida subspecies achromogenes extracellular products (ECP).It was detected in 5 of 9 strains of the organism tested.The protease was purified by anion-exchange fast protein liquid chromatography (FPLC) on Mono Q HR 5/5, and FPLC gel filtration on Superose 12 HR 10/30.The LDso of the purified protease for juvenile Atlantic salmon Salrno salar L. was 0.03 pg protein g-' fish.The molecular weight of the protease was estimated to be 20 kD by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and it possessed 2 isoelectric points (PIS) of 6.2 and 6.4.The protease was completely inhbited by EDTA Indicating it to be a metallo-protease.