Toxicity analysis of azo Red BS and Methyl Red dye solutions on earthworm (Pheretima phosthuma), micro-organisms, and plants

Abstract

Azo dyes containing effluent from various textile industries adversely affects water resources, soil fertility, aquatic organisms as well as animals. Pure cultures of bacteria or bacterial consortia have been successfully applied for the biodegradation of toxic dye effluents. In this view, toxicity analysis of Red BS and Methyl Red dyes and their biologically decolorized solutions were studied on earthworm (Pheretima phosthuma), plants, and micro-organisms. Different types of morphological symptoms were observed upon exposure of dye solutions on earthworm. Mortality rate in terms of LD₅₀ value was determined for both the dye solutions. The LD₅₀ of untreated Red BS and Methyl Red dye solution was 120.22 and 218.77 mg l^−l, respectively. Alteration in the protein content was observed in various organs, head, clitella, and abdomen of earthworms on exposure of dye solutions and the presence of proteins under stress condition was studied using Sodium dodecyl sulphate-Polyacrylamide Gel Electrophoresis. Microbial toxicity study revealed the impact of toxicity to be dependent on dye concentration and biologically decolorized dye samples are less toxic. Phytotoxicity study suggests that, percent germination, length of shoot, and leaf of Phaseolus mungo and Triticum aestivum are adversely affected by the exposure of dye solutions in comparison to the decolorized dye solutions.

Keywords:

• Azo dye
• Earthworm (Pheretima phosthuma)
• Phaseolus mungo
• Triticum aestivum
• Red BS
• Methyl Red