Collaborative Research: MIP: Pressure Influences on Microbial Life in the Puerto Rico Trench

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Pressure is a physical parameter which influences the evolution and distribution of microbial life. Far from Earth?s surface, deep ocean trenches represent the upper boundaries of pressure in the biosphere. This is where scientists can study high pressure adaptations in their most extreme forms. No studies have yet characterized the diversity of microbial life in trenches. In order to do this, Doug Bartlett from UC San Diego and Wilford Schmidt from Univ. Puerto Rico-Mayaguez, will be using an untethered, free-falling, pressured-hardened device to sample bacterial and archaeal life in the deepest trench in the Atlantic Ocean, the Puerto Rico Trench (PRT), at a depth of 8.4 km (5.2 mi). They will profile the ambient environment in which these prokaryotes live (pressure, temperature, salinity, and current velocity). They will also chemically analyze the trench seawater and carry out total microbial cell counts and probe-based counts of particular microbial groups, perform DNA extractions and isolate and culture deep-dwelling microorganisms. It is these last two goals that are at the heart of the project. They will use the DNA to characterize the trench microbial community via indicator genes and community fingerprint techniques. Cultivation of these high pressuring loving microbes (called ?piezophiles?) is difficult since the culture vessels are under very high pressure and the samples are difficult to manipulate. The Bartlett laboratory has the expertise to culture piezophiles and so a major effort will be made to isolate pure cultures of some of the major microbial groups observed in the PRT, including members of the class ?Alphaproteobacteria?, order Flavobacteriales, order Planctomycetales, and subclass marine group I Crenarchaeota. They will also characterize the physiology and taxonomy of particular isolates. In the long term, these investigators are interested in studying the effect of decompression or pressurization on deep-trench or surface-water microbial assemblages because they are interested in understanding the unique abilities of piezophiles to survive and grow under very high pressures. Bartlett and Schmidt will develop outreach programs for pre-college and university students, in Puerto Rico and in southern California, to teach them about this research. Their efforts will include the development of a marine microbiology laboratory class. They will also create highlights from their research for the Birch Aquarium's Deep Ocean Exhibit.