Biosensing systems for the detection and quantification of methane gas

Climate change due to the continuous increase in the release of green-house gasses associated with anthropogenic activity has made a significant impact on the sustainability of life on our planet. Methane (CH₄) is a green-house gas whose concentrations in the atmosphere are on the rise. CH₄ measurement is important for both the environment and the safety at the industrial and household level. Methanotrophs are distinguished for their unique characteristic of using CH₄ as the sole source of carbon and energy, due to the presence of the methane monooxygenases that oxidize CH₄ under ambient temperature conditions. This has attracted interest in the use of methanotrophs in biotechnological applications as well as in the development of biosensing systems for CH₄ quantification and monitoring. Biosensing systems using methanotrophs rely on the use of whole microbial cells that oxidize CH₄ in presence of O₂, so that the CH₄ concentration is determined in an indirect manner by measuring the decrease of O₂ level in the system. Although several biological properties of methanotrophic microorganisms still need to be characterized, different studies have demonstrated the feasibility of the use of methanotrophs in CH₄ measurement. This review summarizes the contributions in methane biosensing systems and presents a prospective of the valid use of methanotrophs in this field. KEY POINTS: • Methanotroph environmental relevance in methane oxidation • Methanotroph biotechnological application in the field of biosensing • Methane monooxygenase as a feasible biorecognition element in biosensors.