Difference between revisions of "Team:UMaryland/Description"

Background

When solar energy is absorbed by the Earth’s surface, the energy radiates back and is then absorbed by greenhouse gases. This absorption causes heat to stay at the Earth’s surface, creating a warming effect. Methane is a potent greenhouse gas in the atmosphere that, though not as abundant as other greenhouse gases, has a major affect on the warming of the planet. The three biggest contributors to methane emissions are fossil fuel production, livestock farming, and landfills.

Different ways of managing methane emissions and reducing the amount of methane production are being to put to use. Legislation passed by the EPA requires Oil and Gas companies to monitor their methane emissions and are required to operate under regulations that require emissions to be under a certain quantity. Methane in landfills is managed by flaring or used in power generators that function as an alternative energy source.

Livestock produce methane gas in their metabolism and manure produces methane as it decomposes. In attempt to control the amount of methane produced by the latter, farms can implement anaerobic digesters that use the biogases produced by anaerobic digestion and decomposition of manure to create an alternative energy or heat source.

However, regulations do not stop the problem, flaring is not 100% effective and can produce air pollutants, and machines that are able to use methane as an energy or heat source can be expensive and difficult to maintain.

A biological alternative to reducing methane in the atmosphere is the implementation of methanotrophs, prokaryotes that metabolize and use methane as their main carbon source.

Strategy

As a way to sequester methane emissions, we will engineer E. coli to be able to metabolize methane. To do this, we have designed two metabolic pathways that take methane to biomass or carbon dioxide.

• Both pathways start with the conversion of methane to methanol using the sMMO gene found in Methylococcus capsulatus, a methanotroph. This gene produces an enzyme that can oxidize methane, therefore converting it to methanol.
• Once the methane is converted to methanol, other engineered E. coli will metabolize the methanol. This will be able to happen in two different pathways that we have designed.
• The first pathway, as we call the fructose pathway, uses a series of enzymes to convert the methanol to a fructose derivative.
• The second, or alternative pathway, as we call the formate pathway, will convert the methanol to carbon dioxide, a much less potent gas, and NADH, a molecule commonly used in redox reactions.
• The engineered bacteria will be co-cultured to provide the complete pathway of methane metabolism.
• This co-culture can be applied to the piping of landfills, where methane gas may escape.