Characterization of urease enzyme from marine bacterium Klebsiella species

The rapidly increasing importance of enzyme urease applications has drawn attention to the need of enzyme study. It prompted the present study to hunt a promising bacterial strain with the desired nature from the Porto Novo coast. Urease enzyme is used in diagnostic kits for measuring blood urea, removal of urea from alcoholic beverages, urease conductometric biosensors for detection of heavy metal ions, etc. In our study, urease enzyme produced by marine bacteria, was isolated, identified and characterized. Samples of water and sediment from Porto Novo coast were taken for analysis. After that, sediment sample showed more number of urease producing bacteria when compared to water sample. Urease producing bacteria were identified as Klebseilla spp, Proteus spp, Lactobacillus spp and Streptococcus spp, from that urease producer Klebseilla spp showed maximum urease production through phenol hypochlorite assay. The potential strain was optimized with their physiochemical parameters showing maximum urease production at 48 h incubation, pH 7, temperature 35 degrees C, salinity 20 ppt producing 1.7, 1.72, 1.67 and 1.72 U/ml, respectively. An optimization with different carbon and nitrogen source showed maximum at 0.7% glucose with 2.05 U/ml and 0.7% peptone with 2.15 U/ml. Mineral supplements 0.03% sodium acetate, 0.04% potassium dihydrogen phosphate, 0.04% nickel sulphate and 0.04% magnesium sulphate showed maximum production of 2.18, 2.27, 2.37 and 2.4 U/ml, respectively. Urea, the enzyme substrate showed maximum production at 0.3% with 2.25 U/ml urease production. Final optimization with inoculum size showed maximum production with increased volume of inoculum with 50 ml of 6 - 8 x 10(7) cell/ml to 500 ml of fermentation medium, showed 2.65 U/ml of urease on 36 h of incubation. Urease enzyme was produced in fermentation medium with the above optimized condition and showed a production of 2.8 U/ml. Then the enzyme was partially purified using dialysis membrane after being fractionated with 60% ammonium sulphate at 5 degrees C. The characterization of urease enzyme from marine bacterium Klebsiella species and the optimization of various physicochemical factors for maximum urease production and its activity stand as a ready reference for more elaborate work of this line in future. The results of the present study will be a base line data for the application of this urease.