Abstract
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).
Highlights
In all cells of the human body, uric acid is the end product of purine nucleotide metabolism, and is excreted out of the body via the kidneys in the urine
Our results show that Aspergillus welwitschiae uricase activity was found to be 60.03 U/mL at inoculum size of 4 mL/50 mL of the production medium, but Hatijah and Ruhayu[34] used 10 mL inoculum to produce uricase from Aspergillus flavus in 90 mL of medium
Our results have shown that the optimal concentration of yeast extract for uricase production was 2 g/L
Summary
In all cells of the human body, uric acid is the end product of purine nucleotide metabolism, and is excreted out of the body via the kidneys in the urine. Rasburicase has been effectively used for the prevention and treatment of hyperuricemia caused by tumor lysis and organ transplants[14]. It is used as an additive in commercial formulations of hair coloring agents[15]. Microorganisms have proven to be a very efficient and economical source of uricase because of their economic cultivation, optimization and purification, facilitating the microbial production of uricase. Some microorganisms such as Gliocladium viride[16], Pseudomonas putida[17] and Nocardi farcinica[18] have been used to produce uricase. Optimization of the medium components and culture condition parameters is the main objective of the biological processes where it has a powerful impact on the production of microbial uricase, as it may effect on product concentration, and the cost of downstream product separation[20]
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