Production and characterization of uricase from Streptomyces exfoliatus UR10 isolated from farm wastes

Authors: MAGDA ALY, SANAA TORK, SALEH AL-GARNI, REDA ALLAM

Abstract: Uricase plays an important role in nitrogen metabolism and can be used medically as a diagnostic reagent. From soil, wastewater, and poultry waste samples collected in Jeddah, 49 bacterial isolates were obtained on either nutrient agar or starch nitrate agar. All the obtained isolates were screened on minimal medium containing 0.5% uric acid for uricase production. The most active bacterium (isolate UR10) produced about 0.5 U/mL of intracellular uricase and was identified as a species belonging to the genus Streptomyces using morphological, physiological, and biochemical characters. By 16S rDNA, it was identified as Streptomyces exfoliatus UR10. Maximum uricase production was obtained using medium 2 with 0.2% uric acid as an inducer, an initial pH of 6.5, and an incubation temperature of 37 °C at 100 rpm. At the end of the incubation period, the cells were collected and disturbed, and the uricase enzyme was precipitated by ammonium sulfate. The enzyme was purified using different column chromatography methods, and the molecular weight of the purified uricase was determined by SDS-PAGE electrophoresis. The optimum temperature for maximum uricase activity was 45 °C; the optimum pH was 8. Co^{2+}, Ni^{2+}, Zn^{2+}, Cu^{2+}, and Pb^{2+} decreased the enzyme activity, whereas Ca^{2+}, Mn^{2+}, Mg^{2+}, and Fe^{2+} stimulated it. In conclusion, uricase was produced by Streptomyces in a medium containing uric acid as inducer, and this enzyme can be used to detect and quantify uric acid in urine and/or blood.

Keywords: Uricase, Streptomyces, molecular weight, uric acid, enzyme activity, 16S rDNA

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