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Methane monooxygenase and their potential role in methane mitigation

corresponding

JOSÉ A. SILVA-GÓNZALEZ, DAVID A. FRAIRE-GARCÍA, CYNTHIA V. OCHOA-BAÑUELOS, LILIA E. MONTAÑEZ-HERNÁNDEZ, MIRIAM P. LUEVANOS ESCAREÑO, NAGAMANI BALAGURUSAMY*
*Corresponding author
Laboratorio de Biorremediación, Facultad de Ciencias Biológicas, Universidad Autónoma de Coahuila, Torreón Coahuila, México

Abstract

Methane monooxygenase is the key role enzyme used by the ubiquitous group of methanotrophs to assimilate methane as a source of energy and carbon. This enzyme in both of its forms, soluble and particulate, lacks of substrate specificity, allowing methanotrophs to use other hydrocarbons as co-substrates. This ability is of special interest in bioremediation applications such as biodegradation of chlorinated compounds and in methane mitigation.  The use of methanotrophic bacteria based technologies has contributed in the development of strategies to reduce methane emissions from “hot spots” such as landfills. The new generation of metagenomics techniques can help to find methanotrophic bacteria with special characteristics to fulfill specific necessities such as high methane affinity for biocovers and biofilter technologies.


INTRODUCTION

Methanotrophs are a group of organisms of great interest for environmental applications due to their unique microbiological and metabolic features. It is estimated that a significant amount of methane from the biosphere is removed through microbiological oxidation by methanotrophic bacteria (1). Applications in bioremediation field for this group of bacteria are based on their ability to use hydrocarbons (mainly methane) as source of energy and carbon. Methanotrophic bacteria owe this metabolic ability to an enzyme called methane monooxygenase (MMO), especially to its soluble form (2). Its lack of specificity allows methanotrophs to take several substrates, including organochloride and aromatic compounds as co-substrates in the process of obtaining energy and transforming them into less polluting compounds, and to a lesser extent also to other enzymes, which take part in the further oxidation of methanol to carbon dioxide (3).

Methanotrophic bacteria

Methanotrophs form a ubiquitous subset of methylotrophic bacteria which belong to the proteobacteria phylum. Due to their ability ...