Abstract
In the present study, Chryseobacterium geocarposphaerae DD3 isolated from textile industry dye effluent in West Bengal, India, displayed significant tolerance to sulfonated di-azo dye Congo red (CR), up to 500 ppm. The optimum decolourisation revealed that C. geocarposphaerae DD3 was capable of 96.52% decolourisation of 0.2 g L−1 CR within 12 h of treatment in the presence of 5 g L−1 glucose as supplementary carbon source. Biodegradation analysis of decolourised CR containing water was investigated by FTIR, MS and 1H NMR, which confirmed the absence of azo bond as well as the toxic aromatic amines. Further, phytotoxicity analysis was performed to assess the toxicity of CR before and after bacterial treatment. Growth indexes of Vigna radiata L. seed confirmed that the biodegraded water was non-phytotoxic in comparison to the control CR solution. Multivariate analyses confirmed the same, showing significant differences between measured plant health indicators for CR solutions, whereas no significant differences were found between distilled and treated water. This study is novel as it is the first report of dye degradation by C. geocarposphaerae and may lead to a sustainable way of treating dye-contaminated water in the near future.
Highlights
Our results show that plants grown in Congo red (CR) aqueous solution probably faced a direct impact from azo dye molecules in terms of germination inhibition, seedling health, and affected shoot-root elongation, whereas toxicity of the dye was substantially reduced after bacterial biodegradation (Table 1)
Textile dye effluent origin thermotolerant bacterium C. geocarposphaerae DD3 was studied for its ability to decolourise CR, followed by degradation and detoxification of CR by the bacterium
Based upon biodegradation analysis of CR, the process seemed to involve a complete biodegradation without forming aromatic amines as secondary pollutants
Summary
Among the plentiful causes of pollution, a major threat is the textile industry, as it often releases dye-containing effluents into natural water bodies [1]. The textile industry plays an important role in any country, it is still an environmental polluter, causing more than 20% of global water pollution alone [2]. As stated by the World Health Organization (WHO), coloured effluents released after dying treatment by textile industries cause 17–20% of total water pollution worldwide. It has been found in a case study that 1.65 mg L−1 azo dye released into the Cristais River, São Paulo, Brazil caused a mutagenic effect in humans [3].
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