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DEGRADATION OF DISSOLVED ORGANIC PHOSPHORUS BY HETEROTROPHIC BACTRERIA IN THE OLIGOTROPHIC OCEAN

In this study we describe pathways and biochemical transformations by which marine heterotrophic bacteria mediate the turnover of dissolved organic phosphorus (DOP). Bacterial growth was stimulated with glucose and nitrogen in microcosm incubations prepared with surface waters of the North Pacific Subtropical Gyre. Bacteria quickly exhausted 83-90% of the soluble reactive phosphorus pool (initially 68.1±0.8 nM at 25 m-depth and 85±2 nM at 125 m-depth) and subsequently proceeded to degrade a considerable fraction (22-44%) of the DOP pool (initially 177.4±2 nM at 25 m-depth and 237.1±21 nM at 125 m-depth) including phosphonates associated with semi-labile dissolved organic matter (DOM). We estimated phosphonate degradation accounted for 3.4-6.4% of DOP degradation by measuring the net production of methane and ethylene, the degradation byproducts of the major phosphonate species in DOM: methylphosphonate and 2-hydroxyethylphosphonate, respectively (Repeta et al., 2016. Nature Geosciences, in press). We also tested the ability of several marine bacterial isolates including a Pseudomonas strain and members of the Roseobacter and Oceanospirillales clades to degrade DOP and DOM phosphonates naturally present in marine surface waters and applied a mutagenesis strategy to identify pathways required to degrade DOM phosphonates. We are now pursuing laboratory studies with model bacterial systems to further elucidate the biological and biochemical mechanisms of DOP turnover.

Authors

Sosa, O. A., Center for Microbial Oceanography: Research and Education, USA, ososa@hawaii.edu

Ferrón, S., Center for Microbial Oceanography: Research and Education, USA, sferron@hawaii.edu

DeLong, E. F., Center for Microbial Oceanography: Research and Education, USA, edelong@hawaii.edu

Repeta, D. J., Woods Hole Oceanographic Institution, USA, drepeta@whoi.edu

Karl, D. M., Center for Microbial Oceanography: Research and Education, USA, dkarl@hawaii.edu

Details

Oral presentation

Session #:003
Date: 02/28/2017
Time: 15:15
Location: 306 A

Presentation is given by student: No