92 Secondary Metabolite-Assisted Protection of an Aerobic Bacterium During Anoxic Stress

Faculty Mentor: Aaron Puri (Chemistry, University of Utah)

All bacteria must overcome nutrient limitation in their environment; a consequence of natural variability and fluctuations within their specific niche. Despite the commonality of this challenge, the strategies bacteria use to survive nutrient limitation are understudied. This applies to methane-oxidizing bacteria (methanotrophs), which use methane as their only source of carbon and energy. Methanotrophs are obligate aerobes, meaning they require oxygen to survive. However, they must also survive periods of low oxygen to obtain methane created by anaerobic communities found deeper in sediments. Rising methane emissions are fueling the rapid warming of our planet, and it is critical that we identify ways to remove methane from our atmosphere. Methanotrophs are useful tools in bioremediation because they serve as methane sinks to sequester this potent greenhouse gas. We recently discovered that a methanotroph, Methylobacter tundripaludum strain 21/22 (21/22), produces a new secondary metabolite called tundrenone. This project investigates the role that tundrenone plays in the survival of 21/22 under anoxic stress. After subjecting cultures of 21/22 to periods of oxygen deprivation, we can assess the viability of the cultures. We found that wild-type 21/22 has increased cell viability when compared with a mutant strain that does not produce tundrenone. We now hypothesize that tundrenone acts as an ionophore or extracellular electron shuttle to support 21/22’s survival in hypoxia. Understanding the mechanism by which 21/22 survives low-oxygen conditions may enable optimization of this organism, and others, as methane-sinks and other useful environmental tools.