Biodegradation of Synthetic Dyes by Bacteria Isolated from Textile Industry Water Effluent

Aims: Biodegradation of synthetic dyes by bacteria isolated from textile industry water effluent.

Study Design: Different bacterial strains were isolated from the water effluent generated by textile industry. These bacteria were identified using morphological and molecular characterization and their ability to degrade synthetic dyes was evaluated. The dyes used in this study were methylene blue, malachite green, congo red, and methyl red.

Place and Duration of Study: Samples were collected from textile industrial area of Mandideep, Raisen (Madhya Pradesh, India). All the experiments were conducted in Department of Microbiology, Barkatullah University, Bhopal (Madhya Pradesh, India) between January 2019 to June 2019.

Methodology: Textile dye effluent was collected from industrial area of Mandideep, Raisen (Madhya Pradesh, India). The collected effluent sample was analyzed for its physical characteristics (pH, temperature, colour, odour, electrical conductivity (EC), total dissolved solids (TDS), chemical oxygen demand (COD), biological oxygen demand (BOD), dissolved oxygen (DO), turbidity, and total hardness). Different bacteria were isolated from this effluent using nutrient agar medium. These bacteria were screened for their ability to degrade synthetic dyes like methylene blue, malachite green, congo red, and methyl red. The potential bacterial isolates were identified using morphological and molecular methods and its ability to degrade synthetic dyes was estimated.

Results: In the current study 24 bacterial isolates were isolated from the textile water and screened for their ability to degrade methylene blue, malachite green, congo red, and methyl red. The secondary screening revealed five bacterial isolates (R-1, R-2, R-6, R-8, and R-14) possess potential of degrading all four dyes. All the isolates were tested for genetic similarity using BOX-PCR which revealed isolates R-1, and R-2 to be similar, therefore four isolates R-1, R-6, R-8, and R-14 were selected for further study. Isolate R-14 effectively degraded 79.84% of methylene blue and 84.23% of methyl red at 200 mg/L respectively after 24 h. 89.3% of 100 mg/L malachite green dye was degraded by isolate R-14 in 72 h. Congo red dye at concentration 100 mg/L was degraded 88.96% by isolate R-8. R-1 and R-6 exhibited 71.1% and 74.6% degradation of methyl red dye respectively at 100 mg/L concentration. All the four potential isolates were identified using 16S r-RNA sequencing which revealed isolate R-1, R-6, R-8, and R-14 to be Pseudomonas geniculata, Bacillus altitudinis, Bacillus subtilis, and Citrobacter freundii respectively. This study reports effective degradation of synthetic dyes using bacterial isolates.

Conclusion: The potential bacteria Pseudomonas geniculata, Bacillus altitudinis, Bacillus subtilis, and Citrobacter freundii can be industrially employed for the biodegradation of synthetic dyes.