New uricase producing Stenotrophomonas isolate recovered from a hot well in western south Egypt: Strain identification, Statistical optimization of enzyme production and in vitro application in gout treatment

Uricase, an enzyme catalyzing the breakdown of uric acid into more soluble compounds, holds significant therapeutic potential in managing hyperuricemia and associated conditions like gout. The current study intended to bioprospect new uricase producers in one of rarely studied ecological niches (ground water well that delivers water from 1500m depth with temperature 50⁰C in Al Qasr Oasis, New Valley Governorate, Egypt). Eight isolates were screened for uricase production, and the most potent was identified using phenotypic and genotypic methods as Stenotrophomonas maltophilia with 99% similarity. This is the first record about the ability of a member in the genus Stenotrophomonas to produce uricase, and was thus targeted in subsequent optimization studies. The initial activity of 7.20 U/mL was obtained in medium No. 2 after testing enzyme production in five different media. The uricase production was then enhanced using statistical design and modeling. Plackett-Burman design (PBD) was used to screen and identify the parameters influencing uricase activity. Four of the nine investigated factors were the most significant and were further optimized using Box-Behnken design (BBD). After two optimization cycles using PBD and BBD, the yield was improved to 20.60 and 25.67 U/mL, respectively, indicating a significant 3.5-fold improvement in the enzyme yield. The uricase was partially purified by ammonium sulphate 75% with 2.58-fold increase in activity (final recovered activity of 87.5%). Under polarized light microscopy, the prepared monosodium urate crystals clumps degraded at different levels of the obtained enzyme which encourages its future application in gout treatment.