Isolation, molecular identification and characterization of the culture conditions for extracellular uricase production by a new strain of Pseudomonas Sp.

The current work details the screening of about
100 isolates from various soil samples, from which 1
isolate was finally selected based on the productivity of
cholesterol oxidase. Further biochemical identification
tests and 16S rRNA gene sequencing identified this
isolate as Streptomyces badius. A preliminary culture
media optimization was carried out using the initial
screening method of Plackett-Burman. Then, a Box-
Behnken design was employed to investigate the optimum
concentrations of medium components and interactive
effects of main variables on cholesterol oxidase
production. The regression analysis showed a significant
coefficient of determination (R2) value (91 %), which
was in close agreement ensuring a satisfactory adjustment
of the proposed model. Maximal enzyme production
(2.38 U/mL, i.e., approximately more than 100 %
activity in the basal medium) was obtained at: temperature
35 °C; Tween 20 0.1 %; pH 6.5 and yeast extract
0.15 %. This two-stage statistical approach provided
rapid identification and integration of key medium
parameters for Streptomyces sp., resulting in high cholesterol
oxidase production