Niloofar Nasirpour

Uricase (EC 1.7.3.3) is an oxidoreductase enzyme that is widely exploited for diagnostic and treatment purposes in medicine. This study focuses on producing recombinant uricase from E. coli BL21 in a bubble column bioreactor (BCB) and finding the optimal conditions for maximum uricase activity. The three most effective variables on uricase activity were selected through the Plackett–Burman design from eight different variables and were further optimized by the central composite design of the response surface methodology (RSM). The selected variables included the inoculum size (%v/v), isopropyl β-d-1-thiogalactopyranoside (IPTG) concentration (mM) and the initial pH of the culture medium. The activity of uricase, the final optical density at 600 nm wavelength (OD₆₀₀) and the final pH were considered as the responses of this optimization and were modeled. As a result, activity of 5.84 U·ml⁻¹ and a final OD₆₀₀ of 3.42 were obtained at optimum conditions of 3% v/v inoculum size, an IPTG concentration of 0.54 mM and a pH of 6.0. By purifying the obtained enzyme using a Ni-NTA agarose affinity chromatography column, 165 ± 1.5 mg uricase was obtained from a 600 ml cell culture. The results of this study show that BCBs can be a highly effective option for large-scale uricase production.

In the present work, bioleaching of two valuable metals of cobalt (Co) and nickel (Ni) from spent lithium-ion batteries (LIBs) of laptop by Acidithiobacill