Construction of bacterial consortium for efficient degradation of mixed pharmaceutical dyes

Synthetic dyes are established colorants in the pharmaceutical industries for the coating and coloration of tablets, capsules, etc. to mark the specific formulation and dosage, improve the stability, and esthetic value. The pharmaceuticals manufacturing process releases large volumes of dye-containing wastewaters, contributing to eco-toxic concerns related to different health risks. In this study, biodegradation of amaranth, sunset yellow, tartrazine, indigo carmine, and quinoline yellow dyes was investigated in the mixed environment. Initially, 24 tolerant bacterial strains were isolated from pharmaceutical wastewater samples, among which 19 strains were found to be non-virulent. Five different consortia were constructed by considering the 19 strains among which C1 consisting of strains DY7, 10, 11, and 18 was found to be the most potential consortium with an overall efficiency of 96.65% dye degradation in the presence of glucose after 15 days. The strains DY7, 10, 11, and 18 were identified as members of the Klebsiella genus by 16S rRNA partial sequencing. The cell wall structure, carbohydrate utilization profile, and metabolic characterization were conducted on the selected strains of C1. Among the 25 different antibiotics, DY7 and DY11 exhibited the highest zone of growth inhibition in the presence of cefixime, and DY10 was restricted by chloramphenicol whereas DY18 was found sensitive to ceftazidime/tazobactam.