title: Thermostable Xanthine Oxidase Activity from Bacillus pumilus RL-2d Isolated from Manikaran Thermal Spring: Production and Characterization.
abstract: Xanthine oxidase is an important enzyme of purine metabolism that catalyzes the hydroxylation of hypoxanthine to xanthine and then xanthine to uric acid. A thermostable xanthine oxidase is being reported from a thermophilic organism RL-2d isolated from the Manikaran (Kullu) hot spring of Himachal Pradesh (India). Based on the morphology, physiological tests, and 16S rDNA gene sequence, RL-2d was identified as Bacillus pumilus. Optimization of physiochemical parameters resulted into 4.1-fold increase in the xanthine oxidase activity from 0.051 U/mg dcw (dry cell weight) to 0.209 U/mg dcw. The xanthine oxidase of B. pumilus RL-2d has exhibited very good thermostability and its t1/2 at 70 and 80 °C were 5 and 1 h, respectively. Activity of this enzyme was strongly inhibited by Hg(2+), Ag(+) and allopurinol. The investigation showed that B. pumilus RL-2d exhibited highest xanthine oxidase activity and remarkable thermostability among the other xanthine oxidases reported so far.
authors: Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India.
authors: Nirmal Kant
authors: NK
authors: Sharma
authors: Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India.
authors: Shikha
authors: S
authors: Thakur
authors: Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India.
authors: Neerja
authors: N
authors: Thakur
authors: Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India.
authors: Savitri
authors: Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 India.
authors: Tek Chand
authors: TC
authors: Bhalla
keywords: Bacillus pumilus; Thermophilic microorganisms; Thermostability; Xanthine oxidase