Biodegradation and toxicity reduction of pulp paper mill wastewater by isolated laccase producing Bacillus cereus AKRC03

Abstract

Wastewater discharged from pulp and paper mills play a major role in environmental pollution and have significant effects on aquatic and terrestrial components. The main focus of this work is to study the potential laccase producing bacterium Bacillus cereus AKRC03 (accession no. MN720581.1) for the biodegradation and toxicity reduction from pulp paper mill wastewater. The isolated strain of Bacillus cereus AKRC03 exhibited up to 78.67% of decolorization and degradation capability for hazardous residual organic pollutants at different nutritional (glucose: 1.0%, peptone: 0.5%) and environmental conditions (pH: 7.0, temperature: 37 °C, agitation: 180 rpm, incubation period: 120 h). The absorption peak of the UV–Vis spectral scan identified the decolorization and degradation pattern for pollutants present in wastewater during treatment. Furthermore, the transformation of major pollutants was exhibited through GC-MS analysis. These were 1-dotriacontanol, 1-heptadecanol, tricosane, 1-(2-hydroxyethoxy) tridecane, and n-[(methylphenyl) methylene]-2-methyl-2-propanamine n-oxide. While silane, (dodecyloxy)trimethyl, (1á,3á,4à)-3,4-bis[dimethyl(4-methylphenyl)silyl]cyclo pentan-1-yl acetate, (2S,3R)-(3-tetradecyloxiranyl)methanol, hexadecanoic acid, 2,3-bis[(trimethylsilyl)oxy]propyl ester, and 2,4,6-tri[4,5-(methylenedioxy)phenyl]-s-triazine appeared as metabolic product after degradation of wastewater. The reduction of toxicity was measured up to 70% for treated wastewater with Phaseolus mungo L seeds and Tubifex tubifex worms. From these findings, it is concluded that the isolated bacterium may be used in the bioaugmentation process for the further detoxification and degradation of discharged pulp paper mill wastewater for environmental safety.