Uricase Production Research Articles

Isolation of a thermostable uricase-producing bacterium and study on its enzyme production conditions

A uricase-producing bacterium was isolated from soil with a medium containing uric acid as the only carbon source. Based on its morphological and physiological characteristics, as well as 16S rDNA sequence and phylogenetic tree analysis, this new isolate belong to the genus Microbacterium. After heat treatment at 70°C for 30min, the uricase retained about 100% of the initial activity. The enzyme activity remained largely unchanged when it was stored in borate buffer at pH 8.5 at 37°C for 40 days. The effects of different factors on the enzyme production were studied. Maize milk was the best C and N resources, and the uric acid showed to be an inducer for uricase production. When the strain was cultured at 30°C at pH 7.5 for 30–36h, the uricase activity peaked at 1.0U/ml.

Improved production of Pseudomonas aeruginosa uricase by optimization of process parameters through statistical experimental designs

Sequential optimization strategy, based on statistical experimental designs, was employed to enhance the production of uricase by Pseudomonas aeruginosa local isolate. Glucose supplementation to the basal production medium inhibits uricase production, perhaps by catabolic repression. For screening of bioprocess parameters significantly influencing uricase activity, the two-level Plackett–Burman design was used. Among fifteen variables tested; pH, CuSO 4 and FeSO 4 were selected based on their high significant effect on uricase activity. A near optimum medium formulation was obtained using this method with increased uricase yield by 15-folds. Response surface methodology (RSM) was adopted to acquire the best process conditions. In this respect, the three-level Box–Behnken design was employed. A polynomial model was created to correlate the relationship between the three variables and uricase activity. The optimal combination of the major constituents of media for uricase production evaluated from the non-linear optimization algorithm of EXCEL-Solver was as follows: pH, 5.5; CuSO 4, 10 −3 M; and FeSO 4, 10 −2 M. The predicted optimum uricase activity was 7.1 U/ml/min, which is 16.5 times than the basal medium.

Bioconversion of poultry wastes. I--Factors influencing the assay and productivity of crude uricase by three uricolytic filamentous fungi.

The optimum temperature for biomass yield and uricase production by uricolytic fungi, Aspergillus terreus, A. flavus and Trichoderma sp. was at 30 degrees C. The time required for maximum production of uricase and biomass yield was 4 days for two Aspergillus species and 6 days for Trichoderma sp. The optimum pH was at 6.4 for A. terreus and pH 6.6 for A. flavus and Trichoderma sp. The maximum fungal biomass yield was achieved in medium supplemented with 4% poultry waste. The best carbon sources for the production of uricase and mycelia yield were glycerol, sucrose and maltose by A. terreus, A. flavus and Trichoderma sp., respectively. Uric acid was found to be the best nitrogen source for production and activity of uricase by the three tested fungi. The addition of some vitamins to the culture media increased the maximum biomass yield of all the isolates, although no significantly increased uricase production was found.

Neuro-fuzzy prediction of uricase production

Recent biotechnology requires implementation of new modelling methods based on knowledge principles and learning structures, comprised in fuzzy knowledge-based systems (FKBS), neural networks (NN) and different hybrid methods. The intelligent modelling approaches solve sufficiently a very important problem – processing of scarce, uncertainty and incomplete numerical and linguistic information about multivariate non-linear and non-stationary systems as well as biotechnological processes. The paper deals with prediction of an enzyme oxidizing uric acid to alantoin – the uricase, produced by Candida utilis 90-12 employing neuro-fuzzy knowledge-based approach. The implemented predictive technique exploits the fact that the fuzzy model can be seen as a network structure, similar to artificial NN, which on computational level assure a high model accuracy. The predictors implemented are four different by nature variables. The developed predictive model shows that best predictors of uricase production are biomass and limiting substrate concentrations.

State estimation of a Uricase production process with Candida Utilis

The present work discusses the implementation of a Kalman filtering procedure in a state estimation of a batch Uricase production process with Candida Utilis. An unstructured model of the process is used for the estimation procedure. The observability is thoroughly investigated and a Kalman filter is applied afterwards as a powerful and precise state estimation tool. The estimates in all cases of observability are presented, compared and discussed.

State estimation of a Uricase production process with

State estimation of a Uricase production process with

Construction of catalase deficient Escherichia coli strains for the production of uricase.

To produce catalase-free uricase preparations, we constructed catalase-deficient strains from Escherichai coli MC1000 and MM294 and used them as recombinant host strains. The parent strains and catalase-deficient strains showed no differences in the growth characteristics by shaking culture in Erlenmeyer flasks. The catalase deficient strain derived from MC1000 transformed with the uricase expression plasmid pUT118 (strain SN0037) had growth characteristics and the uricase productivity comparable to those of the parent host strain MC1000 in fed-batch culture in a jar fermentor and no catalase activity was detected in cell-free extracts. However, the katG disrupted strains from MM294 carrying pUT118 had poor growth and their uricase productivities were low compared to those of the parent strain MM294. Using the strain SN0037, a catalase-free uricase preparation was obtained with fewer purification procedures and the final recovery of uricase activity was improved. The catalase-deficient E. coli host strain will be a suitable host for the production of the uricase, free of catalase activity, in high yield.

Rapid extraction of uricase from Candida utilis cells by use of reducing agent plus surfactant

We sought to make easier the production of uricase ( urate: oxygen oxidoreductase, EC 1.7.3.3) and found that this enzyme was rapidly extracted from Candida utilis cells by treatment with a reducing agent plus a surfactant when the culture broth was between pH 7.0 and 10.0. Some nonionic and cationic surfactants were effective in the extraction of uricase. Of the various reducing agents tried, thiol compounds such as 2-mercaptoethanol ( 2-ME) also increased extraction in the presence of 0.1% Triton N-101. For the extraction of much uricase, the amount of 2-ME needed was 0.02% or more. The maximum extracellular enzyme activity ( 0.523 U ml −1 broth) was obtained with Triton N-101 at 0.1% or more concentration in a broth of pH 8.0 containing 0.1% 2-ME. Between pH 7.0 and 10.0, where uricase was stable, the enzyme was rapidly extracted into the culture broth. The uricase activity obtained by this method was higher than that obtained by conventional methods such as autolysis and sonication, which gave activities of 0.306 and 0.359 U ml −1 broth, respectively.

Production of uricase by different strains of Streptomyces

Production of uricase by different strains of Streptomyces

Production of uricase by Candida tropicalis using n-alkane as a substrate

Production of uricase (urate oxidase, EC 1.7.3.3) by n-alkane-utilizing Candida tropicalis pK233 was studied. Although the yeast showed very low enzyme productivity under growing conditions on glucose or an n-alkane mixture (C10 to C13) (less than 2 U/g of dry cells), enzyme formation was enhanced markedly in an induction medium consisting of potassium phosphate buffer, MgSO4, uric acid, and an n-alkane mixture (47 U/g of dry cells) or glucose (21 U/g of dry cells). Of the carbon sources tested, the n-alkane mixture was the most suitable for enzyme production. Appropriate aeration also stimulated uricase formation. In addition to uric acid, xanthine, guanine, adenine, and hypoxanthine were also effective for inducing uricase. Under optimum conditions, the maximum yield of the enzyme was 91 U/g of dry cells. Uricase thus induced was localized in the microbodies of the yeast.

鶯糞より分離した一糸状菌のウリカーゼ生産特性(第1報)高塩濃度および亜鉛塩によるウリカーゼ生成促進

A Hyphomycetes, strain F1, isolated from the excrements of Cettia diphone cantans was found to have the following characteristics on uricase production. 1) This strain was resistant to a high concentration of KCl or NaCl, and the addition of about 4.0% of these salts to the medium gave the maximum uricase production, which the was about two times in dry weight of the pellicle and about 15 times in the amount of enzyme compared to the normal fungal medium containing 0.05% of the salts. 2) The zinc-salt was found to be the only accelerator for the uricase production by this strain after detailed examination of various metal salts. Maximum uricase production was obtained by incubating this strain for 5 days in the medium containing 0.001-0.01 % of ZnSO4·7H2O or ZnCl2, when the amount of the enzyme was increased 3-4 fold compared to the absence of zinc salt.

The characteristics of uricase production by a Hyphomycetes isolated form the excrements of Cettia diphone cantans. II. The effectiveness of purines and pyrimidines as substrates (author's transl)

The effectiveness of purines and pyrimidines as substrates for the induced production of uricase was studied in F-1 strain of Hyphomycetes, in a medium containing casamino acids, as a good nitrogen source for the growth of this strain. The purines were incorporated into the cells at a relatively early stage of the growth and then the enzyme was induced from all the substrates. No other substrates were found more effective than uric acid. The relationship between the amount of added uric acid and uricase production was examined in the following two cases : (1) The maximum concentration of uric acid in the medium was increased to 0.08% by dissolving uric acid into alkaline solution before adding it into the direct medium. Under this condition, the uricase production increased in proportion to the concentration of uric acid added. (2) The amount of uric acid added in the basal medium was increased to 0.30%, beyond its solubility, and undissolved uric acid precipitated in the bottom of Fernbach's culture vessel. In this experiment, there was no distinct relationship between the amount of uric acid added and uricase production. The precipitated uric acid started to dissolve slowly into the medium during the culture and its concentration in the medium increased markedly during the cultured process. Increase in the solubilizing capacity of the medium to uric acid was also observed as in the basal medium.

The characteristics of uricase production by a Hyphomycetes isolated from the excrements of Cettia diphone cantans. V. Uricase production by pellicle in various growing stages (author's transl)

The characteristics of uricase production by a Hyphomycetes isolated from the excrements of Cettia diphone cantans. V. Uricase production by pellicle in various growing stages (author's transl)

The characteristics of uricase production by a Hyphomycetes isolated from the excrements of Cettia diphone cantans. IV Effect of amino acids as nutritional substances (author's transl)

The characteristics of uricase production by a Hyphomycetes isolated from the excrements of Cettia diphone cantans. IV Effect of amino acids as nutritional substances (author's transl)

Studies on the Formation of Uricase by Streptomyces

The induced formation of uricase by the cultured cells of Streptomyces sp. and the effect of purine bases on the enzyme formation were studied. The microorganism was grown in media containing urate and/or purine bases (adenine, guanine, hypoxanthine or xanthine) and the development of the uricase activity of the cells were measured at intervals. The disappearance of urate and purine bases from the media was also determined. Without the purine bases, the production of uricase was significantly low even in the presence of urate and the disappearance of urate from the medium was in a slow rate. Upon the addition of hypoxanthine or xanthine in the presence of urate, a significant increase in the uricase activity of the cells and a concomitant rapid decrease of urate in the medium were observed. The purine bases added to the media were incorporated into the cells at a relatively early period of the culture and appeared to be converted into urate within the cells. The repression of uricase formation in the cult...