Extracellular urease from Arthrobacter creatinolyticus MTCC 5604: scale up, purification and its cytotoxic effect thereof.

Urease is a potent metalloenzyme with diverse applications. This paper describes the scale up and purification of an extracellular urease from Arthrobacter creatinolyticus MTCC 5604. The urease production was scaled-up in 3.7 L and 20 L fermentor. A maximum activity of 27 and 27.8 U/mL and a productivity of 0.90 and 0.99 U/mL/h were obtained at 30 h and 28 h in 3.7 and 20 L fermentor, respectively. Urease was purified to homogeneity with 49.85-fold purification by gel filtration and anion exchange chromatography with a yield of 36% and a specific activity of 1044.37 U/mg protein. The enzyme showed three protein bands with molecular mass of 72.6, 11.2 and 6.1 kDa on SDS-PAGE and ~ 270 kDa on native PAGE. The cytotoxic effect of urease was assessed in vitro using cancer cell lines (A549 and MG-63) and normal cell line (HEK 293). Urease showed its inhibitory effects on cancer cell lines through the generation of toxic ammonia, which in turn increased the pH of the surrounding medium. This increase in extracellular pH, enhanced the cytotoxic effect of weak base chemotherapeutic drugs, doxorubicin (50 µM) and vinblastine (100 µM) in the presence of urease (5 U/mL) and urea (0-4 mM) significantly.

Non-enzymatic reduction of Cr (VI) and it's effective biosorption using heat-inactivated biomass: A fermentation waste material.

The effectiveness of heat-inactivated fungal biomass a fermentation waste of newly isolated laccase enzyme producer Leiotrametes flavida was studied for Cr (VI) removal in water and applied for Cr (VI) removal from tannery effluent. Adsorption parameters pH, biomass concentration and contact time were optimized using Box-Behnken design of response surface methodology. The adsorption process fits the Langmuir isotherm. Thermodynamic and kinetic studies showed that the process is spontaneous at ambient temperature and followed the second-order kinetics model, respectively. The values of the kinetic model indicated that the adsorption process is a combination of physisorption and chemisorption. Chromium adsorption onto the biomass was confirmed by SEM-EDAX, FTIR, XPS and XRD analysis. XPS analysis confirmed the reduction of Cr (VI) to Cr (III). The amount of chromium adsorbed was 72.38 % and 68.33 % for water and effluent, respectively. Chromium adsorbed onto biomass was desorbed at pH 9 with 1 M NaOH. Total chromium desorbed was 61.40 and 59.38 percent from water and effluent, respectively. The amount of Cr (III) in the desorbed sample was 71 and 68 percent, respectively. The heat-inactivated biomass of Leiotrametes flavida is a suitable material for efficient Cr (VI) removal and detoxification.