[Proteolytic and elastase activities of Pseudomonas aeruginosa]

We studied 20 strains of Pseudomonas aeruginosa in its ability to produce proteolytic enzymes. Three different culture media were used: one containing salts and yeast; another one, the dialysed brain-heart-broth fluid and the third, brain-heart-broth. The best was the last one. The purification of the enzymes was performed by precipitation with ammonium sulphate and Sephadex G--100 gel filtration. The number of enzymes acting on casein were demonstrated by means of zymogram previously separated by polyacrylamide gel electrophoresis (Fig. 2). All the strains acted on gelatin and 80% of them on elastin. 80% of the 20 strains studied showed a correlation between the activity on elastin and the activity on casein (Fig. 1). 25% of the strains showed the presence of two enzymes using zymogram and 75% only one enzyme. The results were independent of the culture medium used. Strains recently isolated showed to produce a high level of proteolytic enzymes. When the strains were kept in the laboratory the activity decreased to low levels until almost disappeared (Fig. 1). When the recently isolated strains showed two proteolytic enzymes by zymogram, the less active one disappeared throughout the time when kept in the laboratory. The composition of the purified enzymes were proteic in nature; neither lipoprotein nor glycoprotein were evidenced.