Characterization of potential MnP producing bacteria and its metabolic products during decolourisation of synthetic melanoidins due to biostimulatory effect of d-xylose at stationary phase

Sucrose-aspartic acid Maillard product (SAA-MP) is the major colourant of distillery effluent as environmental pollutant due to its recalcitrant nature. Three potential manganese peroxidase (MnP) producing bacteria were screened for higher SAA-MP tolerance (3200 mg/l) and characterized as Bacillus species (IITRM7, FJ581030), Raoultella planticola (IITRM15, GU329705) and Enterobacter sakazakii (IITRM16, FJ581031). The consortium of these bacteria showed maximum decolourisation (60%) of SAA-MP (2400 mg/l) in modified GPYM medium at optimized nutrient, pH (7.0 ± 0.2), shaking speed (180 rpm) and temperature (35 ± 2 °C) after 144 h incubation. The addition of d-xylose enhanced the decolourisation of SAA-MP from 60 to 75% along with reduction of BOD and COD. The electrospray ionization-mass spectrum (ESI-MS) analysis showed removal of various compounds after bacterial growth and decolourisation of SAA-MP. Formation of new products showed metabolization of SAA-MP. Thus this consortium might be useful for decolourisation of industrial wastewater containing high concentration of melanoidins. d-xylose could be used as biostimulator for this consortium during decolourisation of SAA-MP.