SELFISH UPTAKE OF POLYSACCHARIDES BY MARINE HETEROTROPHIC BACTERIA AT ELEVATED HYDROSTATIC PRESSURE

Heterotrophic bacteria turnover half of the organic matter that is produced by phytoplankton in the ocean. Much of this organic matter is in the form of polysaccharides, complex high-molecular weight sugars. Previously, it was thought that bacteria had to hydrolyze this organic matter to small sizes outside the cell, releasing hydrolysis products to the environment. Within the last decade, however, an alternative mechanism of uptake— ‘selfish uptake’—has been discovered. Using selfish uptake, bacteria bind, partially hydrolyze, and transport large fragments of polysaccharides into the cell with little to no loss of hydrolysis products. To date, selfish uptake has been investigated in both the surface and deep ocean, but potential impacts of hydrostatic pressure have not been investigated. Therefore, in three field expeditions, we measured the extent of selfish uptake in surface and deep waters, under pressures ranging from atmospheric up to ~50 MPa (equivalent to 5,000 m depth). Preliminary data suggests differences in the extent of selfish uptake in surface waters between samples that were pressurized and those that were kept under atmospheric pressure. We also explored the extent of selfish uptake from the deep ocean using an in-situ incubator. Results from these experiments will help us quantify the extent to which pressure affects the mechanisms by which heterotrophic bacteria process polysaccharides throughout the global ocean.

Presentation Preference: Oral

Primary Presenter: Chad Lloyd, University of North Carolina at Chapel Hill (cchadlloyd@gmail.com)

Authors:

C. Chad Lloyd, Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill  (cclloyd@unc.edu)

Eleanor Hennessey, Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill  (ejhennes@unc.edu)

Laura Pareigis, Microbial-Carbohydrate Interactions Group, Faculty of Chemistry/Biology, University of Bremen  (laura.pareigis@gmx.de)

Devangi Sathe, HADAL & Nordcee, Department of Biology, University of Southern Denmark  (devangi@biology.sdu.dk)

Sherif Ghobrial, Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill  (reef@unc.edu)

John Paul Balmonte, Department of Earth and Environmental Sciences, Lehigh University; Lehigh Oceans Research Center, Lehigh University  (jpb422@lehigh.edu)

Greta Reintjes, Microbial-Carbohydrate Interactions Group, Faculty of Chemistry/Biology, University of Bremen  (greta.reintjes@gmail.com)

Ronnie Glud, HADAL & Nordcee, Department of Biology, University of Southern Denmark; Danish Institute of Advanced Study (DIAS), University of Southern Denmark; Department of Ocean and Environmental Sciences, Tokyo University of Marine Science and Technology  (rnglud@biology.sdu.dk)

Carol Arnosti, Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill  (arnosti@email.unc.edu)