Kyle Metcalfe
California Institute of Technology
2019 Schlanger Fellow – Kyle Metcalfe
Abstract
Minerals host the marine subsurface biosphere, but it remains unknown if specific minerals present in marine sediments play a role in facilitating microbial survival in the deep biosphere. Conductive minerals have been shown to stimulate the metabolic activity of microorganisms sampled from the subsurface, suggesting subsurface microorganisms may associate with these phases in situ. I hypothesize that biosynthetically-active microorganisms in the deep biosphere associate with conductive minerals. I propose to test this hypothesis by applying mineral separation techniques to incubations of sediment from IODP Expedition 370 followed by downstream microbial community analysis via iTag sequencing corroborated by fluorescence in situ hybridization (FISH) and evaluation of biosynthetic activity employing bioorthogonal noncanonical amino acid tagging (BONCAT).
Biography
My interest in geobiology and environmental microbiology was first sparked during my undergraduate thesis with Professor Robert Gaines at Pomona College. Through this project, in which I examined dissimilatory reduction of ferric iron bound in clay minerals, I learned to appreciate the dazzling diversity of the microbial world and its profound impact on global biogeochemistry. I sought to further explore the interplay between microbiology and geochemistry through my PhD work with Dr. Victoria Orphan at Caltech, where I’ve applied novel mineral separation techniques to seafloor sediments to parse the microbial ecology of sediments at unprecedented resolution. In my project funded by the Schlanger Fellowship, I will apply these novel techniques to sediments retrieved from the marine deep subsurface on IODP Expedition 370 with the aim of revealing new insight into microbe-mineral and microbe-microbe interactions in the deep biosphere.