Primary and Secondary Screening of Pseudomonas aeruginosa for Protease Production

  • Asawer A. Kareem Muayad S. Shawkat


The current study was aimed for inhibition of purified protease produced by Pseudomonas aeruginosa using alcoholic extract of Conocarpus lancifolius leaves. A total of one hundred forty-six of isolates of P. aeruginosa that were isolated and identified by microscopic and biochemical tests were fifty-one isolates submitted to primary and secondary screening techniques in order to choose the qualified P. aeruginosa isolate for protease synthesis. Among these isolates, forty-seven isolates with the show hydrolysis zone on skim milk media (primary screening) were chosen six isolates for secondary screening. The result revealed that P. aeruginosa P51 had the highest ability to produce the enzyme (specific activity 15.9 U/mg protein). The optimum conditions of protease production by the selected isolate in submerged fermentation by using tryptic soya broth medium as best substrate, temperature 37°C and pH 8, after 48 h of incubation. In addition, the study was included extraction of C. lancifolius crude by using 80% ethanol. It was concluded revealed a significantly decreasing in specific activity of protease (from 15.9 to 4.2 U/mg) after treated it with 0.4 µg/ml of alcoholic extract of C. lancifolius crude extracts.