Abstract
Low molecular weight polycyclic aromatic hydrocarbons (PAHs) like naphthalene and substituted naphthalenes (methylnaphthalene, naphthoic acids, 1-naphthyl N-methylcarbamate, etc.) are used in various industries and exhibit genotoxic, mutagenic, and/or carcinogenic effects on living organisms. These synthetic organic compounds (SOCs) or xenobiotics are considered as priority pollutants that pose a critical environmental and public health concern worldwide. The extent of anthropogenic activities like emissions from coal gasification, petroleum refining, motor vehicle exhaust, and agricultural applications determine the concentration, fate, and transport of these ubiquitous and recalcitrant compounds. Besides physicochemical methods for cleanup/removal, a green and eco-friendly technology like bioremediation, using microbes with the ability to degrade SOCs completely or convert to non-toxic by-products, has been a safe, cost-effective, and promising alternative. Various bacterial species from soil flora belonging to Proteobacteria (Pseudomonas, Pseudoxanthomonas, Comamonas, Burkholderia, and Novosphingobium), Firmicutes (Bacillus and Paenibacillus), and Actinobacteria (Rhodococcus and Arthrobacter) displayed the ability to degrade various SOCs. Metabolic studies, genomic and metagenomics analyses have aided our understanding of the catabolic complexity and diversity present in these simple life forms which can be further applied for efficient biodegradation. The prolonged persistence of PAHs has led to the evolution of new degradative phenotypes through horizontal gene transfer using genetic elements like plasmids, transposons, phages, genomic islands, and integrative conjugative elements. Systems biology and genetic engineering of either specific isolates or mock community (consortia) might achieve complete, rapid, and efficient bioremediation of these PAHs through synergistic actions. In this review, we highlight various metabolic routes and diversity, genetic makeup and diversity, and cellular responses/adaptations by naphthalene and substituted naphthalene-degrading bacteria. This will provide insights into the ecological aspects of field application and strain optimization for efficient bioremediation.
Highlights
The rapid expansion of industries has led to global economic prosperity and better living standards
The contaminated ecosystems harbor vast microbial diversity with dynamic metabolic flexibility. It often lacks suitable conditions, i.e., robust microbial members with metabolic pathways and its regulation for complete mineralization, nutrients required for metabolism, and other biotic/abiotic factors
Other properties like chemotaxis, cell surface/membrane fluidity, compartmentalization of pathway, and biosurfactant production are advantageous for the enhanced metabolism of polycyclic aromatic hydrocarbons (PAHs)
Summary
The rapid expansion of industries (petrochemical, agricultural, pharmaceutical, textile and dyes, cosmetic, etc.) has led to global economic prosperity and better living standards. Naphthalene and its derivatives [methyl naphthalenes, naphthoic acids, naphthalene sulfonates and 1-naphthyl N-methylcarbamate (carbaryl)], have been considered as priority organic pollutants by the USEPA with genotoxic, mutagenic, and/or carcinogenic effects (Cerniglia, 1984) The release of such LMW-PAHs in the environment results in the bioaccumulation of these compounds in the food chain at various levels, affecting the health of the ecosystem (Binkova et al, 2000; Srogi, 2007; Quinn et al, 2009). We intended to focus on low molecular weight PAHs like naphthalene and substituted naphthalenes These compounds are found to be the main components of petroleum-derived fuels, textile dyes, consumer products, pesticides (mothballs and insect repellents), plasticizers, and tanning agents, ubiquitously present in many ecosystems (Preuss et al, 2003).
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
