Methanotrophs: An emerging bioremediation tool with unique broad spectrum methane monooxygenase (MMO) enzyme

Abstract

This review is proposed to emphasize the contribution of methanotrophs as potential bioagents in mitigating the effect of toxic environmental pollutants like heavy metals, petroleum hydrocarbons, lindane (γ-HCH) and trichloroethylene (TCE). Methane-oxidizing bacteria (methanotrophs) are widespread in natural environments and have emerged as one of the potential bioagents in the environmental remediation. Methanotrophs are fast emerging as potential tools of bioremediation due to the presence of methane monooxygenase (MMOs: pMMOs and sMMO) enzymes with unique characteristics of utilizing the broad spectrum of organic substrates. The MMOs can co-metabolize aliphatic halides, aromatic compounds, heavy metals, etc. The significant role of MMOs in biodegradation activity of methanotrophs, examined in situ condition, supports the argument that pMMO performed better in methane-augmented bioremediation. Stimulated rate of methanotrophic bioremediation could be better accomplished through the addition of methane, oxygen and other nutrients. Defining the temporal and spatial relationships and population dynamics of methanotrophs in natural environmental setting would be the crucial factors for evaluation of bioremediation potential. Besides, adaptability, genetic modifications and manageability of indigenous methanotrophs are the important components required for achieving a viable, more sustainable and eco-friendly bioremediation technology. So, it is considered that application of methanotrophs, particularly extremophilic methanotrophs, would help us to overcome the limitations of conventional methods of pollution mitigation due to their unique physiology, phylogenetic diversity and presence of MMOs.