Abstract EANA2024-91

Beyond Earth, the largest accessible inventory of organics can be found on Saturn’s moon, Titan, due to its carbon-rich atmosphere of approximately 5% methane. The exposure of complex organics such as nitrogenous hydrocarbons to liquid water is critical to the theory of abiogenesis, and not dissimilar to processes that may have occurred on a haze-laden early Earth. At present, surface conditions on Titan are prohibitive for life. Most of Titan’s water is locked in water-ice with transient melting occurring through impact-melt and cryovolcanism. As the Sun ascends the red giant branch, increasing luminosity will cause an increase in Titan’s surface temperature, potentially unlocking liquid water across the planetary surface. Thus, for a geologically short period of time, Titan could meet the three conditions necessary for life. The solubility of nitriles in liquid water (and ammonia-water mixtures) is high, under which hydrolysis can occur to form amides and carboxylic acids, molecules which may be bioavailable for metabolic processes to potential microbial life forms. This raises questions in regards to Titan’s future habitability. Alcanivorax borkumensis has unusual metabolic pathways that allow it to degrade hydrocarbons, in particular alkanes, making it a useful model organism for non-traditional metabolic versatility. To investigate this, we have assayed the tolerance and utilisation of aliphatic nitriles as mimetic tholins across three microbial species, Bacillus subtilis, Alcanivorax borkumensis, and a currently unidentified fungal species. Results have found that A. borkumensis can tolerate and utilise up to 20% v/v acetonitrile, with the fungal contaminant appearing to grow in 50% v/v acetonitrile. Future work will further explore the habitability of nitrile-rich medias, particularly investigating how the aliphatic chain length affects microbial tolerance.