Abstract
In the biosphere, the largest biological laboratory, increased anthropogenic activities have led microbes to evolve and adapt to the changes occurring in the environment. Compounds, specifically xenobiotics, released due to such activities persist in nature and undergo bio-magnification in the food web. Some of these compounds act as potent endocrine disrupters, mutagens or carcinogens, and therefore their removal from the environment is essential. Due to their persistence, microbial communities have evolved to metabolize them partially or completely. Diverse biochemical pathways have evolved or been assembled by exchange of genetic material (horizontal gene transfer) through various mobile genetic elements like conjugative and non-conjugative plasmids, transposons, phages and prophages, genomic islands and integrative conjugative elements. These elements provide an unlimited opportunity for genetic material to be exchanged across various genera, thus accelerating the evolution of a new xenobiotic degrading phenotype. In this article, we illustrate examples of the assembly of metabolic pathways involved in the degradation of naphthalene and its derivative, Carbaryl, which are speculated to have evolved or adapted through the above-mentioned processes.
Highlights
Anthropogenic activities like manufacturing, industrialization and combustion of fossil fuels have led to the release of a large number of compounds in the environment, which were previously unknown to the biosphere
We focus on the metabolism and various genetic elements involved in the assembly of the degradative pathways for naphthalene and its derivative, Carbaryl
Microbes evolve genes for novel pathways encoding xenobiotic degradation by the above mechanisms, which are further assembled as transcription unit(s)/operon(s), so as to finetune their regulation
Summary
Anthropogenic activities like manufacturing, industrialization and combustion of fossil fuels have led to the release of a large number of compounds in the environment, which were previously unknown to the biosphere. Due to the highly reduced nature, resonance stabilized structure, greater hydrophobicity, and lower aqueous solubility, they are resistant to biodegradation (recalcitrant) They act as metabolic inhibitors, endocrine disrupters [1] and further reactive epoxide formed due to metabolic activation of these compounds by microsomal enzymes interacts with DNA, causing mutation(s) or chromosomal damage [2,3,4] which may lead to cytotoxicity, genotoxicity and/or carcinogenicity [5]. Naphthalene is ubiquitous in the environment and used extensively in the manufacture of various compounds including pesticides and plastics, as well as for domestic consumption (mothballs, insect repellent) Being hydrophobic, it partitions into the membranes [8] and gets accumulated in tissues of aquatic organisms, leading to toxicity [9,10]. Various bacterial species belonging to genus Pseudomonas, Rhodococcus, Mycobacterium, Nocardia, Bacillus, Vibrio, Marinobacter, Micrococcus and Sphingomonas have been reported to degrade naphthalene and Carbaryl
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
