Phylogenetic tree showing the relatedness of multi-copper oxidase CopA of the bacterial isolates. The phylogenetic tree was constructed using neighbor-joining method. Values of 1000 bootstrap replicates above 50% are given at the branching point. Sequences of CopA proteins of the bacterial isolates Sphingomonas sp. strain O12, Sphingomonas sp. strain A32, Sphingomonas sp. strain A55, Stenotrophomonas sp. strain C21 and Arthrobacter sp. strain O4 are highlighted (black circles).