CueO of K. pneumoniae KW is an active enzyme exhibiting laccase like activity. A, the enzyme activity was determined against some phenolic substrates in respective buffer systems across a range of pH. The optimum activity for SGZ and DMP was found at pH 6.5 and 8, respectively; B, CueO activity with various metal ions as co-factors depicted that Cu is the sole cofactor for CueO amongst the ones used in the experiment.