Efficient degradation of Malachite Green dye by Bjerkandera adusta XX-2 strain in an air-opening system

Abstract:

[objective] Our aim was to evaluate the ability of Bjerkandera adusta XX-2 strain in degrading Malachite Green (MG) dye in order to provide reference for its application in treating dye wastewater. [Methods] Batch experiment was carried out to decolorize MG dye in an air-opening system in this study. Experimental parameters, such as oxygen demand, initial pH value, temperature, initial dye concentration, incubation time, carbon source, nitrogen source, metal ion and salinity, was investigated to analyze their effect on the decolorization of MG. The toxicity test of decolorized products on plant, aquatic animal and microorganism was also carried out in this study. [Results] B. adusta XX-2 strain showed efficient decolorization of MG dye without supplying basic salt medium in non-sterile culture, for example, decolorization rate still reached above 60% at the initial dye concentration of 120 mg/L, using MG as sole nutrient source. Static culture presented the similar MG decolorization rate as shaken culture, indicative of low-cost application potential for B. adusta XX-2 strain. The optimal pH and temperature for decolorization were 7.0 and 25 °C, respectively. Based on the system with optimal parameters, carbon source, nitrogen source and metal ion were separately added for choosing appropriate dosage. The results indicated that carbon source (e.g. sodium citrate), nitrogen source (e.g. ammonium chloride) and metal ion (e.g. Zn2+), even at a low concentration, all could greatly improve the efficiency of decolorization. Moreover, B. adusta XX-2 could decolorize MG in dye solution with high salinity. Toxicity test showed toxicity of decolorized products on plant, aquatic animal and microorganism greatly declined, in comparison with non-decolorized MG dye. [Conclusion] B. adusta XX-2 strain had a good application potential for treating dye wastewater.