Congo red degrading laccases from Bacillus amyloliquefaciens strains isolated from salt spring in Serbia

•Two halotolerant Bacillus sp. were isolated from salt spring in Serbia.•Detected laccases have temperature optimum of 65 °C towards ABTS.•Resistance to inhibition by high concentration of chloride ions is observed.•Spore laccase degraded more than 85% of azo dye Congo red at pH 5.7.•Laccases retains ∼55% activity in 25% methanol and ∼45% in 25% DMSO.

Halotolerant strains of Bacillus amyloliquefaciens were isolated from salt spring in Ovca spa located in Republic of Serbia. Strains exhibit robust spore laccase with high temperature optimum of 65 °C while pH optimum is wide and substrate dependant. Ability to oxidize azo dyes was demonstrated. Under optimized conditions more than 85% removal of Congo red dye was achieved at pH 5.7. Substantial resistance to inhibition by high concentration of chloride ions was observed and tolerance of some commonly used cosolvents shows that applicability of these laccases goes beyond decolorization of textile effluents.