Life Underground: Investigating Microbial Communities and Their Biomarkers in Mars-Analog Lava Tubes at Craters of the Moon National Monument and Preserve

Craters of the Moon National Monument and Preserve (CotM) is a strong terrestrial analog for lava tube formations on Mars. The commonality of its basalt composition to Martian lava tubes makes it especially useful for probing how interactions between water, rock, and life have developed over time, and what traces of these microbial communities may be detectable by current flight-capable instrumentation. Our investigations found that secondary mineral deposits within these caves contain a range of underlying compositions that support diverse and active microbial communities. Examining the taxonomy, activity, and metabolic potential of these communities revealed largely heterotrophic life strategies supported by contributions from chemolithoautotrophs that facilitate key elemental cycles. Finally, traces of these microbial communities were detectable by flight-capable pyrolysis and wet chemistry gas chromatography-mass spectrometry methods comparable to those employed by the Sample Analysis at Mars (SAM) instrument aboard the Curiosity rover and the Mars Organic Molecule Analyzer (MOMA) on the upcoming Rosalind Franklin rover. Using a suite of methods for chemical derivatization of organic compounds is beneficial for resolving the greatest variety of biosignatures. Tetramethylammonium hydroxide (TMAH), for example, allowed for optimal resolution of long chain fatty acids. Taken together, these results have implications for the direction of mass spectrometry as a tool for biosignature detection on Mars, as well as informing the selection of sampling sites that could potentially host biosignatures. © 2022. American Geophysical Union. All Rights Reserved.6 month embargo; first published: 03 November 2022This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Quorum-Quenching Acylases in Pseudomonas aeruginosa

The β-lactam acylases, mostly found by screening samples from natural sources, represent a unique family of heterodimeric N-terminal nucleophile hydrolases. Interestingly, most of the strains found producing β-lactam acylases are Pseudomonas species. We have shown that these enzymes show high selectivity towards the acid side chain, but are far more promiscuous with regard to the amine moiety of the substrate. It is therefore highly unlikely that the industrially relevant deacylation of β-lactam compounds has evolved specifically in nature. Interestingly, no less than four putative acylases of the N-terminal nucleophile family have been identified in the Pseudomonas aeruginosa PAO1 genome. We have investigated these four putative acylases of which one could be expressed in Escherichia coli. Interestingly, the enzyme was found to catalyse the hydrolysis of acylhomoserine- lactones as reported for Ralstonia acylase suggesting a role in quorum quenching..