Symbiosis involving bacteria and invertebrates plays a critical role in sustaining the high productivity observed in many marine environments. Perhaps most unusual are symbiotic partnerships that have allowed organisms to exploit ephemeral, recalcitrant, and sometimes toxic aquatic environments. Exploitation of energy in these environments often requires metabolic and physiological capabilities that cannot be accomplished by animals alone. One such symbiosis includes a unique partnership between a newly discovered group of polychaete worm Osedax (Latin = bone-devouring) and a microbe related to aerobic, hydrocarbon-degrading members of the group Oceanospirillales. This unusual association is the only known symbiosis capable of using the decaying bones of sunken marine mammals as a sole source of nutrition. The symbiotic microbe provides a nutritional bridge between high-energy compounds and the worm host, yet very little is known about the specific mechanisms that enable this novel ecological strategy. The goal of this project is to understand the specific nutritional integration between Osedax worms and their endosymbionts, including the metabolic capabilities of the novel symbiont and the pathways for converting carbon substrates into energy. This will be investigated using culture techniques to isolate the symbionts, along with molecular and biochemical methods, including functional gene amplification and measures of enzyme activity in both partners. These worms and their microbial symbionts likely play substantial roles in the cycling of organic compounds in marine communities. Remineralization of organic carbon, facilitated almost entirely by Osedax and its symbiont, is approximately 2000 years faster than the typical avenue of carbon delivery to the deep seafloor, a habitat representing approximately 50% of the Earth's surface. This project includes the goal of expanding interest in bacterial/animal interactions to the general public. Symbiosis, or the living together of different organisms, has dramatically affected life on Earth. Outreach programs, such as a proposed exhibit at the Long Beach Aquarium of the Pacific will showcase this research, with emphasis on general marine microbiology and microbial symbioses.
