RIDGE: Postdoctoral Fellowship: Characterization of Endolithic Microbial Communities in Ocean Ridge Basalt Glasses: An Interdisciplinary Approach

Oregon State University, Corvallis OR

Investigators

Abstract

Microbes beneath the Earth's surface are now thought to make up a significant amount of life on Earth, and the vast majority of this life is beneath the ocean floor. At underwater volcanoes in the ocean basins (known as the mid-ocean ridges), these microbes are the base of the food chain and they fuel an ecosystem that uses chemical energy from the Earth and not sunlight. Communities of microbes at mid-ocean ridges appear to promote the break down of rocks and alter the composition of sea water that circulates beneath the volcanoes. These microbes are mostly known from circumstantial evidence, so their variety, abundance, and their effect on the physical and chemical properties of the ocean crust are unknown. The PI will investigate the deep-ocean biosphere with a multi-faceted approach that combines chemical analysis of mineral in basalts with characterization of the resident microbial communities. The research objectives are: 1) To verify the presence of microbial communities within rocks from mid-ocean ridges. 2) To describe the minerals associated with the microbial communities. 3) To characterize the microbial communities in terms of overall biomass, physiological state, and genetic diversity. These objectives are important to a number of related fields of science, such as global chemical budgets of carbon and other elements, the origin and history of life, the search for life elsewhere in the solar system, the use of microbes in mining and groundwater mediation, and the search for antibiotics. This interdisciplinary investigation relies on a combination of microscopy, geochemistry, and molecular genetic techniques. Epifluorescence and scanning electron microscopy will be used to locate microorganisms in rocks, and an electron microprobe will be used to identify the minerals associated with the microbes and locate areas within rocks with high concentrations of elements required for life (C, N, and P). Epifluorescence microscopy and stains that bind to nucleic acid will be used to verify microbial DNA is present. Molecular genetic approaches will be used to identify the microbial DNA extracted from the basalts and generate profiles of community composition. Nucleic acid probes specific for organisms of interest will be hybridized in situ and visualized with epifluorescence. The physical association of microbes and minerals will be used to demonstrate ways in which endolithic microorganisms can alter the geochemistry of ridge crest basalts.