Xanthine oxidase is a highly versatile and ubiquitous complex molybdoflavoprotein, which controls the rate
limiting step of purine catabolism pathway. Microbial xanthine oxidase can be used to address a number of questions
presently not feasible with the eukaryotic enzymes. In the present study, a high-throughput microtitre plate-based colorimetric
assay for xanthine oxidase producing microorganism was developed. Superoxides produced by microbial cultures,
grown on xanthine rich medium interacts with nitroblue tetrazolium (NBT) solution and produces dark blue color,
which facilitates the rapid screening of xanthine oxidase producing microorganisms and could be adapted for quick quantitative
assessment and distribution of xanthine oxidase in many heterogeneous microbial communities. The method developed
may be utilized for the rapid screening of a variety of xanthine oxidase producing microorganisms from the nature.