Bioremediation of synthetic and textile dyes effluent by extremophiles

Most textile industries dump their washed off synthetic dyes along with heavy metals and salts into rivers creating wastewater that is extremely toxic to its flora and fauna. These toxic compounds get bio-accumulated in the food chain and are harmful to humans. The need for remedial approaches to “clean up” these waters has thus been an important research avenue. A key problem posed by these contaminated waters is their extreme characteristics such as high salinity and heavy metal content which hamper the physical, chemical and biological remedial approaches being investigated. Over the years, a significant approach identified by researchers is the use of extremophilic organisms and their enzymes in order to degrade these dyes in situ as well as ex situ. Extremophiles or extreme-condition loving organisms have the natural ability to survive and thrive in stressful conditions such as extreme pH, extreme salinity, extreme temperatures and extreme pressure. More recently there has been a keen interest in mining the potential of these organisms to degrade and detoxify synthetic dyes from wastewater. A variety of halotolerant, alkaliphile, and thermostable bacterial and fungal species as well as their enzymes, isolated from a variety of environments, has been studied in vitro for their dye-detoxifying abilities. We discuss a selected set of extremophiles and their characteristics in this chapter. In addition to some of the conventional microbiological methods, we also discuss some modern approaches that are being used to identify, isolate and optimize the extremophiles as well as extremozymes produced by them. These include 16s rRNA sequencing, the use of a microbial consortium, a recombinant approach to enzyme production and site-directed mutagenesis.