Anaerobic biodegradation of anthraquinone dye reactive black 19 by a resuscitated strain Bacillus sp. JF4: Performance and pathway

Abstract

Anthraquinone dyes are known for their resistant nature and challenging biodegradation in harsh environmental conditions. In this study, the potential of a resuscitated strain Bacillus sp. JF4 for degrading the refractory anthraquinone dye Reactive Blue 19 (RB19) was investigated. The results demonstrated that JF4 was capable of effectively degrading RB19 using glucose and peptone as co-substrates at 3 g/L each. Notably, JF4 exhibited excellent RB19 biodegradation over a broad pH range (7−9) and NaCl concentrations (0–40 g/L). Under optimal conditions of pH 7.0 and 30 °C, JF4 efficiently degraded RB19 at concentrations of 25–150 mg/L, achieving almost complete degradation of 125 mg/L RB19 within 184 h. The biodegradation process of high RB19 concentrations (75–150 mg/L) by JF4 followed a first-order kinetic model, with an increasing half-life (t1/2) as RB19 concentration rises. Enzyme activity analysis revealed significant induction of lignin peroxidase, indicating its active role in RB19 biodegradation. The degradation pathways of RB19 by JF4 were proposed based on the analysis of metabolites and enzymes, involving reductive cleavage of RB19 followed by further degradation through oxidoreductive enzymes. These findings highlighted the high-efficient RB19-degrading capability of the resuscitated strain JF4 with remarkable alkalinity and salinity tolerance, providing new insights for cultivating effective bio-inoculants in the treatment of anthraquinone dye-containing wastewater.