Production and partial characterization of uric acid degrading enzyme from new source Saccharopolyspora sp. PNR11

Isolation and Characterization of Highly Active Uricase from Alcaligenes spp. Strain UR1

For the first time, this study reports extracellular uricase enzyme isolation and characterization from strain UR1 of Alcaligenes spp. from Western Saudi Arabia. The strain efficiently produced highly active extracellular uricase for therapeutic applications. It offers a simplified enzyme purification approach rather than complicated intracellular enzyme purification from other microbes. Strain UR1 exhibited significantly higher uricase synthesis potential [916 U/mg (specific activities) and 275 U/ml (volume)]. The study optimized the conditions (37°C and pH 7.4) for 10% enhanced uricase production in the BT medium where sucrose served as the carbon source. Uricase enzyme remained stable at various pH levels (5-9) up to 50°C, however, the optimal activity was noted at 40°C and pH 7.5. The strain was sensitive to EDTA-like inhibitors. Ca2+ improved the strain activity, which could yield potent formulations for clinical and industrial applications. This novel aspect presents Alcaligenes spp. strain UR1 as a promising candidate for the treatment of hyperuricemia and gout. It offers an efficient and inexpensive alternative for uricase synthesis at the industrial scale. These findings encourage further investigations regarding genetic aspects of uricase for improved bioprocessing and therapeutic applications.

Streptomyces griseorubens as a microbial cell factory for extracellular uricase production and bioprocess optimization using statistical approach

BACKGROUND

Uricase is a bio-drug used to reduce urate accumulation in gout disease. Thus, there is a continuous demand for screening soil samples derived from a variety of different sources in order to isolate a strain that possesses a high potential for producing uricase.

METHODS

Streptomyces sp. strain NEAE-5 demonstrated a significant capacity for uricase production was identified based on the physiological, morphological and biochemical characteristics, as well as 16S rDNA sequencing analysis. Using a Plackett-Burman statistical design, the impact of eighteen process factors on uricase production by Streptomyces griseorubens strain NEAE-5 was investigated. Using central composite design, the most important variables that had a favourable positive impact on uricase production by Streptomyces griseorubens strain NEAE-5 were further optimized.

RESULTS

It is clear that the morphological and chemotaxonomic features of Streptomyces sp. strain NEAE-5 are typical for the Streptomyces genus. Phylogenetic analysis indicated that Streptomyces sp. strain NEAE-5 belongs to the genus Streptomyces and closely related to Streptomyces griseorubens which it has a 95-96% identity in 16S rDNA gene sequencing. Accordingly, the strain is proposed to be identified as Streptomyces griseorubens strain NEAE-5. The three factors that had the significant positive impacts on uricase production were uric acid, hypoxanthine, and yeast extract. As a result, the best conditions for achieving the highest experimental uricase production by Streptomyces griseorubens strain NEAE-5 after central composite design were (g/L): uric acid 6.96, glycerol 5, hypoxanthine 5.51, MgSO4.7H2O 0.1, KNO3 2, CaCl2 0.5, K2HPO4 0.5, NaCl 0.5, yeast extract 1.08. In addition, the period of incubation is seven days, pH 7.5 and 37 °C with an inoculum size of 2 mL (105 cfu/mL) /100 mL medium.

CONCLUSIONS

After optimization, the obtained uricase activity was 120.35 U/mL, indicating that the Streptomyces griseorubens strain NEAE-5 is a potent uricase producer and that the statistical approach used for optimization was appropriate.

Optimized UV-Spectrophotometric Assay to Screen Bacterial Uricase Activity Using Whole Cell Suspension

Uricase catalyzes the conversion of uric acid into allantoin with concomitant reduction of molecular oxygen to hydrogen peroxide. In humans, uricase is not functional, thereby predisposing individuals to hyperuricemia, a metabolic disturbance associated with gout, chronic kidney disorders, and cardiovascular diseases. The efficacy of current therapies to treat hyperuricemia is limited, and novel approaches are therefore desired, for instance using uricase-expressing probiotic strains. Here, we evaluated UV-spectrophotometric and H₂O₂-based fluorescent assays to enable the rapid identification of uricase activity in a broad panel of lactobacilli, Bacillus, and Bifidobacterium species. We highlighted abiotic (medium composition and mode of sterilization) and biotic (H₂O₂-producing strains) factors impacting the measurements' accuracy, and reported on the stepwise optimization of a simple, fast, and robust high-throughput UV-spectrophotometric method to screen uricase activity using whole bacterial suspension, thereby assessing both cell-associated and extracellular activity. The validity of the optimized assay, based on the monitoring of uric acid degradation at 300 nm, was confirmed via liquid chromatography. Finally, a panel of 319 Qualified Presumption of Safety (QPS) strains of lactobacilli (18 species covering nine genera), Bacillus (three species), and Bifidobacterium (four species) were screened for uricase activity using the optimized method. All 319 strains, but the positive control Bacillus sp. DSM 1306, were uricase-negative, indicating that this activity is rare among these genera, especially in isolates from food or feces. Altogether, the UV-spectrophotometric high-throughput assay based on whole bacterial suspension reported here can be used to rapidly screen large microbial collections, by simultaneously detecting cell-associated and extracellular uricase activity, thereby accelerating the identification of uricolytic strains with therapeutic potential to treat hyperuricemia.

A new uricase from Bacillus cereus SKIII: Characterization, gene identification and genetic improvement

Twenty-five microbial isolates were investigated for uricase production on uric acid medium. All isolates were obtained from Jeddah, Saudi Arabia. The highest uricase producer was identified as Bacillus cereus SKIII. Using glucose peptone broth at pH 7.5, incubation temperature 30 °C for 3 days with shaking of 150 rpm were the best conditions for maximum enzyme production. Glucose and peptone were the best carbon and nitrogen sources. The molecular weight of the purified enzyme was34.5 KDa, and isoelectric point was 7.9. The optimum pH and temperature were pH 8.0 and 35 °C, respectively. It was stable at 35 °C for 60 min, but thermally inactivated at 60 °C after 60 min Its enzymatic activity was enhanced by Mg²⁺, Ca²⁺,Fe²⁺, Mn^2+, Zn²⁺ions and inhibited by Co²⁺, Na⁺, Hg²⁺, Ag⁺ ions and EDTA at 1 mM. Uricase production was enhanced using UV mutation and the obtained mutant produced six times higher than the original isolate. An amplicon 900 bp of uricase gene (Pucl) was sequenced (accession number MF417635). No remarkable difference was noticed in B. cereus SKIII and SKm mutant nucleotide sequences. In conclusion, SKIII and SKm are promising strains in uricase production for biotechnological applications.

Mathematical modeling for bioprocess optimization of a protein drug, uricase, production by Aspergillus welwitschiae strain 1-4

Microbial uricase is effective protein drug used to treat hyperuricemia and its complications, including chronic gout, also in prophylaxis and treatment of tumor lysis and organ transplants hyperuricemia. Uricase is commonly used as diagnostic reagent in clinical analysis for quantification of uric acid in blood and other biological fluids. Also, it can be used as an additive in formulations of hair coloring agents. A newly isolated strain, Aspergillus sp. 1–4, was able to produce extracellular uricase on a medium containing uric acid as inducer. Phylogenetic analysis based on ITS region sequence analysis and phenotypic characteristics showed that Aspergillus sp. strain 1–4 is closely related to Aspergillus welwitschiae and its nucleotide sequence was deposited in the GenBank database and assigned sequence accession number MG323529. Statistical screening using Plackett-Burman design with 20 runs was applied to screen fifteen factors for their significance on uricase production by Aspergillus welwitschiae. Results of statistical analysis indicated that incubation time has the most significant positive effect on uricase production followed by yeast extract and inoculum size with the highest effect values of 13.48, 5.26 and 4.75; respectively. The interaction effects and optimal levels of these factors were evaluated using central composite design. The maximum uricase production was achieved at incubation time (5 days), yeast extract (2 g/L) and inoculum size (4 mL/50 mL medium) are the optimum levels for maximum uricase production (60.03 U/mL). After optimization, uricase production increased by 3.02-folds as compared with that obtained from the unoptimized medium (19.87 U/mL).