Bacillus amyloliquefaciens laccase – From soil bacteria to recombinant enzyme for wastewater decolorization

•Bacillus sp. isolated from soil across Serbia were screened for laccase activity.•Detected laccases exhibits high temperature optimum and stability.•Promising laccase was cloned and expressed in Escherichia coli using pET-21a vector.•Recombinant laccase completely degraded dye Reactive blue 52 at pH 4.0–7.0.•Dye degradation products were analyzed by HPLC-DAD and FTIR spectroscopy. 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.