Proteolytic activity of four strains of Pseudomonas on crude extracts of contractile proteins

Hydrolytic activities of exogenous proteases obtained from Pseudomonas upon crude extracts of contractile proteins were studied. Four strains were used: C61 and C20, isolated from beef samples, and P. fragi (ATCC-4973) and P. fluorescens (NRRL-B-1244). Proteolytic activity was tested on crude extracts of actomyosin, myosin+ actin+regulatory proteins, actin and high molecular weight proteins obtained from postrigor beef by differential precipitation according to their solubility in salt solutions of various ion strengths. Electrophoresis analysis showed considerable degradation of actomyosin in samples treated with a C61 enzymatic extract. Myosin degradation was similar for treatments with proteases obtained from C61 and P. fragi. Actin degradation was similar for all enzymatic extracts. The most active protease was a 46.8 kDa enzyme produced by C60. P. fragi produced two proteases of 49.2 kDa and 34.2 kDa, P. fluorescens one of 46.1 kDa, and C20 one of 49.2 kDa.