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 t 1/2 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.

Control of biofouling by xanthine oxidase on seawater reverse osmosis membranes from a desalination plant: enzyme production and screening of bacterial isolates from the full-scale plant

“…) and thermostable Bacillus pumilus isolated from a hot spring (Sharma et al . ) has been documented. It is of interest to note that the aforementioned organisms as well as our isolates that have tested positive for xanthine oxidase production belong to extreme environments.…”

“…Recently a thermostable xanthine oxidase enzyme was identified from Bacillus species (Sharma et al . ). This enzyme has also been identified in various other bacteria such as Arthrobacter (Woolfolk and Downard ), Enterobacter (Machida and Nakanishi ) and Pseudomonas (Sakai and Jun ).…”