One hundred wild type strains of Bacillus sp. were isolated from industrial and agricultural soil across Serbia
and screened for laccase activity. Three strains showed high laccase activity temperature optimum of
65 and 80 C towards ABTS. A new laccase gene from the strain with highest temperature optimum,
namely Bacillus amyloliquefaciens 12B was cloned and expressed in Escherichia coli. Recombinant laccase
degraded dye Reactive blue 52 at pH 7.0 and pH 4.0 and at elevated temperature, while fungal laccases
was unable to act on this substrate at pH higher than 4.0 and was quickly inactivated at temperatures
higher than 45 C. Degradation of dye was monitored by HPLC-DAD and resulting precipitate was analyzed
by FTIR spectroscopy. Single product peak without chromophore was detected in solution, while
water insoluble aggregate, presumably dye polymer is formed retaining blue color.