Biodegradation of textile dye Reactive Blue 160 by Bacillus firmus (Bacillaceae: Bacillales) and non-target toxicity screening of their degraded products

Selvaraj Barathi,Chinnannan Karthik,Nadanasabapathi S,Indra Arulselvi Padikasan

doi:10.1016/j.toxrep.2019.11.017

Abstract

The study was envisioned to evaluate the decolorization of Reactive Blue 160 (RB160) dye by using indigenous microbes. Contaminated soil from textile dye industry was collected from Noyyal river basin, Tamil Nadu, India. Potential dye degrading bacterial strain was recognized as Bacillus firmus by 16SrRNA gene sequencing analysis. RB160 dye (500 μg/ml) was effectively degraded by B. firmus and toxicological analyses were performed with RB160 and their degraded product. Phytotoxicity revealed that degraded product of RB160 into non-toxic nature by B. firms. Toxicity assays were carried out on root cells of Allium cepa and human skin cell line (CRL 1474). Toxicity analysis of A. cepa and cell line signifies that dye exerts toxic cause on the root cells and IC50 values of RB160 showed toxic to human skin cell lines, while degradation products of the dye are moderately less in toxic. Zebrafish embryo toxicity also evaluated by RB160 and degraded product on phenotypic deformation, survival, hatching and heartbeat rate. However, RB160 with concentration of 500 μg/ml decrease in the survival, hatching, heartbeat rate and induced phenotypic alterations. In which, degraded products exhibited significant development in zebrafish embryos as compared to dye. Based on the studies effects of RB160 and capability of B. firmus can effectively degrade RB160, and their degraded products were harmless to the environments and aquatic system.

Highlights

Aquatic environmental pollution caused by discharge of raw effluents from various manufacturing industries, is a major environmental problem in worldwide [1]
This result indicated that the metabolites produced after degradation of Reactive Blue 160 (RB160) are less toxic in nature as compared to intact dye to the plants
The degraded metabolites were nontoxic to the experimented plants; subsequently the bacterial strain could be employed for remediation of textile waste ex situ or in situ

Summary

Introduction

Aquatic environmental pollution caused by discharge of raw effluents from various manufacturing industries, is a major environmental problem in worldwide [1]. Among them textile industries used large amount of potable water, for example 200 l of potable water consumed to create 1 kg of textile products, untreated waste water discharged to aquatic environments [2]. These textile industry effluents contain more toxic compounds, which are deleterious to all living organisms. The presence of reactive dyes in water bodies prevents sunlight penetration and oxygen supply prominent to a natural demand for oxygen and creating an unfavorable impact on the water quality, and exhibit higher level of toxicity to plants and other aquatic animals [5,6]. Humans and animals are facing a higher risk of infections and other serious diseases like cancer and skin allergy, infection when the dosage of this mutagenic dyes increase [7]

Methods

Results

Conclusion