Potential metabolic viability on asteroid chemistry

While it has been long supposed that asteroids played a role in the delivery of important prebiotic compounds to early Earth, the exact nature of the interactions between asteroidal material and metabolism remains largely unquantified. Pristine material from asteroid sample-return missions provides an unprecedented opportunity to evaluate the potential for the asteroids' chemistry to support the origin and persistence of life. Here we use metabolic network expansion to computationally test the viability of contrasted biochemical networks, including a group of acetogens and methanogens representing primitive metabolisms, on the known chemistry of three asteroids (Itokawa, Ryugu, Bennu) and two meteorites (Murchison, Murray). The chemistry of Murchison and Bennu appears to support the potential viability of the acetogenic and methanogenic metabolisms. In contrast, Murray, Ryugu and Itokawa samples lack critical substrates, particularly adenine and D-ribose needed for ATP production, suggesting that carbonaceous bodies vary in their compositional capacity to support the acetogenic and methanogenic metabolisms. This highlights the astrobiological relevance of asteroids rich in carbon, nitrogen, and phosphate such as Bennu, and hints at the habitability, past or present, of their parent bodies.