Proteolytic enzyme preparation from Pseudomonas fragi: its action on pig muscle

An extracellular preparation from Pseudomonas fragi with proteolytic enzyme activity was isolated, and its action on meat proteins and meat protein ultrastructure was studied. First, a suitable growth medium for proteolytic enzyme production was determined, and a method for partial purification of the proteolytically active fraction was developed. The enzyme preparation displayed optimal proteolytic activity at neutral pH and 35 C. Proteolytic activity was irreversibly lost by mild heat treatment. The enzyme preparation was tested for its ability to hydrolyze isolated pig muscle proteins. Myofibrillar protein was rapidly degraded, G-actin and myosin were broken down at a slower rate, and the sarcoplasmic proteins were least susceptible to hydrolysis. Electron micrographs of pork muscle showed that the proteolytic enzyme preparation caused a complete loss of dense material from the Z line. Similarities are discussed between the action of P. fragi extracellular proteolytic enzyme(s) on meat and normal bacterial spoilage of meat.