Methanotrophic bioreactors offer a promising solution for atmospheric methane removal [1]. However, bottlenecks remain including mass transfer limitations of methane into liquid media, catalytic efficiency of atmospheric (a.k.a. high affinity) methanotrophs, and slow growth rates of methanotrophs on dilute methane streams that limit their deployment and utility.

Aside from biological limitations, proper placement and scaling of methanotrophic bioreactors must take into account geographical and materials constraints to achieve a measurable impact on atmospheric methane concentrations, and thus the rate of temperature increase, within the next 20-30 years.

The limitations of methanotrophic bioreactors can be mitigated through the use of gas permeable materials inoculated with high affinity methanotrophic bacteria [2]. These bacteria are physiologically flexible as some strains can co-oxidize hydrogen and carbon monoxide along with methane, fix nitrogen, and grow from atmospheric to high methane concentrations. Key goals in developing solid-state atmospheric methane bioreactors include improvement and optimization of strain performance with variable substrate and oxygen concentrations, removing growth limitations, and preventing nutrient/carbon flow bottlenecks through genetic improvement.

Successful development of solid-state bioreactors for atmospheric methane removal include: improved understanding of physiological limitations of high affinity methanotrophs and how to overcome them; optimizing feeding strategies to improve catalytic efficiency, growth rates, and ability to metabolize methane at 2 ppm; genetic models and systems for strain improvement, methods for fabricating solid-state bioreactor materials at meaningful dimensions for atmospheric methane removal; procedures for inoculating solid-state bioreactors at high density to promote continued growth and atmospheric methane oxidation activity of biomass.