غربال گري بيولوژيك و شناسايي اشريشيا كولي مولد آنزيم پني سيلين C آسيلاز و بهينه سازي شرايط توليد آنزيم

Biological Screening and identification of penicillin G acylase producing E. coli and optimization of production condition

Penicillin G acylase (PGA) of Escherichia coli is one of the most widely used enzymes at industrial scale. It is used to hydrolvse penicillin G to 6-aminopenicillanic acid, an essential intermediate in the production of semisynthetic penicillins. Due to high industrial importance of PGA, numerous efforts have been made towards screening for strains overproducing this enzyme. The objective of this study was to screen clinical samples for isolation and identification of E. coli strains producing PGA enzyme. The E. coli bacteria isolated from clinical samples were screened for PGA activity using the bioassay method. This method is based on the use of Serratia marcescens which is sensitive to 6-APA but comparatively resistant to benzylpenicillin. After primary screening, the PGA production in positive isolates was verified by biochemical assay. Finally, the effects of incubation time, temperature, PAA concentration and media PH on PGA synthesis were studied and the optimum conditions for process were determined. The PDAB colorimetric method was used for quantitative PGA activity assay. Among 121 E. coli isolates were studied, only 3 isolates showed the PGA activity but one of them had higher activity. For the selected strain, the optimal condition for enzyme production was obtained in 0.1% PAA, media PH of 7-8, incubation time of 48h and incubation temperature of 32°C. The results of this study showed that biological screening method is a rapid and efficient method for identification of PGA producing bacteria.