Long-Term Exposure to Azo Dyes from Textile Wastewater Causes the Abundance of Saccharibacteria Population

Ramasamy Krishnamoorthy,James Prabhakaran,Rangasamy Anandham,Jeongyun Choi,Tongmin Sa,Aritra Roy Choudhury,Murugaiyan Senthilkumar,Kiyoon Kim,Polpass Arul Jose,Kathirvel Suganya,Nellaiappan Olaganathan Gopal

doi:10.3390/app11010379

Ramasamy Krishnamoorthy, James Prabhakaran + Show 9 more

Open Access

https://doi.org/10.3390/app11010379

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Abstract

Discharge of untreated wastewater is one of the major problems in various countries. The use of azo dyes in textile industries are one of the key xenobiotic compounds which effect both soil and water ecosystems and result in drastic effect on the microbial communities. Orathupalayam dam, which is constructed over Noyyal river in Tamil Nadu, India has become a sink of wastewater from the nearby textile industries. The present study had aimed to characterize the bacterial diversity and community profiles of soil collected from the vicinity of the dam (DS) and allied agricultural field (ALS) nearby the catchment area. The soil dehydrogenase and cellulase activities were significantly lower in DS compared to ALS. Additionally, the long-term exposure to azo dye compounds resulted in higher relative abundance of Saccharibacteria (36.4%) which are important for degradation of azo dyes. On the other hand, the relative abundance of Proteobacteria (25.4%) were higher in ALS. Interestingly, the abundance of Saccharibacteria (15.2%) were also prominent in ALS suggesting that the azo compounds might have deposited in the agricultural field through irrigation. Hence, this study revealed the potential bacterial phyla which can be key drivers for designing viable technologies for degradation of xenobiotic dyes.

Highlights

The cellulase activity is higher in soils which are rich in plant biomass [30], and it corroborates to our study where the cellulase activity has been observed to be highly significant in Agricultural Soil (ALS)
The long-term exposure of wastewater from textile industries has resulted in changes in soil enzyme activities and bacterial diversity
The azo-dye contamination caused the Saccharibacteria population to proliferate in higher abundance compared to other bacterial phyla in Dam Soil (DS)

Summary

Introduction

Soil is a biologically balanced system and any variations in the soil micro-environment results in the changes in native microbial community profiles. Heavy metals [3] have drastic effect on the bacterial diversity. The driving factors which determine the abundance of the microbial community in a particular contaminated soil are the genetic variation which results in altered metabolic pathways or the selective enrichment of microbes which are able to transform the particular pollutant [4]. Rapid advent of industrialization has led to deleterious effect on the environment, mostly due to the improper discharge of industrial waste. The textile industries use a large amount of synthetic dyes which results in discharge of colored wastewater [5,6]

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