Methane eaters

The ways in which organisms make a living is constantly throwing up surprises. In Nature this week there is a paper by Ettwig et al. that describes something truly unexpected. Many microbial organisms make use of methane, in fact there had been 3 recognized routes for methane metabolism - which involve either producing or 'eating' methane. Methane, as we all know from playing with matches and bunsen burners, is chock full of chemical energy.  Of the eating variety of organisms, then either molecular oxygen is used to oxidize methane, or in the absence of oxygen a less efficient oxidation takes place (also seemingly requiring a symbiotic relationship between different microbes).

The rather amazing discovery by Ettwig and collaborators is of an organism Methylomirabilis oxyfera - a bacterium that actually makes its own oxygen in-situ in order to then oxidize methane the more efficient way. In effect this organism generates its own internal supply of oxygen, like a little submarine, neatly sidestepping the need for an oxygen rich atmosphere.

As these authors recognize, this had implications that go far beyond the terrestrial sludge that such microbes live in. The Earth's atmosphere only became oxygen rich after a couple billion years, so there could have been a real advantage in being able to forage methane independently. Methane is also present, if not abundant, in many environments in our solar system, and it's a great energy source for life - but to make the most of it life needs oxygen kicking around. By circumventing the need for environmental oxygen then M. oxyfera seems to have found the solution - make it yourself. Yet again, what we find on Earth suggests that life is very, very good at eking out a living, and that there is less and less reason to think of non-terrestrial environments as hostile for organisms.