Isolation and identification of a novel laccase (namely Lac4) with various industrial applications potentials from an endophytical bacterium. Endophyte Sd-1 cultured in rice straw showed intra- and extra-cellular laccase activities. Genomic analysis of Sd-1 identified four putative laccases, Lac1 to Lac4. However, only Lac4 contains the complete signature sequence of laccase and shares at most 64 % sequence identity with other characterized bacterial multi-copper oxidases. Recombinant Lac4 can oxidize non-phenolic and phenolic compounds under acidic conditions and at 30-50 A degrees C; K-m values of Lac4 for ABTS at pH 2.5 and for guaiacol at pH 4.5 were 1 +/- A 0.15 and 6.1 +/- A 1.7 mM, respectively. The activity of Lac4 was stimulated by 0.8 mM Cu2+ and 5 mM Fe2+. In addition, Lac4 could decolorize various synthetic dyes and exhibit the degradation rate of 38 % for lignin. The data suggest that Lac4 possesses promising biotechnological potentials.