Publication Date:
2022-05-25
Description:
© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 8 (2017): 1786, doi:10.3389/fmicb.2017.01786.
Description:
Semi-labile dissolved organic matter (DOM) accumulates in surface waters of the oligotrophic ocean gyres and turns over on seasonal to annual timescales. This reservoir of DOM represents an important source of carbon, energy, and nutrients to marine microbial communities but the identity of the microorganisms and the biochemical pathways underlying the cycling of DOM remain largely uncharacterized. In this study we describe bacteria isolated from the North Pacific Subtropical Gyre (NPSG) near Hawaii that are able to degrade phosphonates associated with high molecular weight dissolved organic matter (HMWDOM), which represents a large fraction of semi-labile DOM. We amended dilution-to-extinction cultures with HMWDOM collected from NPSG surface waters and with purified HMWDOM enriched with polysaccharides bearing alkylphosphonate esters. The HMWDOM-amended cultures were enriched in Roseobacter isolates closely related to Sulfitobacter and close relatives of hydrocarbon-degrading bacteria of the Oceanospirillaceae family, many of which encoded phosphonate degradation pathways. Sulfitobacter cultures encoding C-P lyase were able to catabolize methylphosphonate and 2-hydroxyethylphosphonate, as well as the esters of these phosphonates found in native HMWDOM polysaccharides to acquire phosphorus while producing methane and ethylene, respectively. Conversely, growth of these isolates on HMWDOM polysaccharides as carbon source did not support robust increases in cell yields, suggesting that the constituent carbohydrates in HMWDOM were not readily available to these individual isolates. We postulate that the complete remineralization of HMWDOM polysaccharides requires more complex microbial inter-species interactions. The degradation of phosphonate esters and other common substitutions in marine polysaccharides may be key steps in the turnover of marine DOM.
Description:
Financial support for this work was provided by the National Science Foundation Center for Microbial Oceanography: Research and Education (award #EF0424599 to DK and ED), the National Science Foundation HOT program (OCE-1260164 to M. J. Church and DK), the Gordon and Betty Moore Foundation (grants #492.01 and #3777 to ED, #3298 to DR, and #3794 to DK), and the Simons Foundation (award ID 329108 to DK, DR, and ED). Additional support was provided by the Agouron Institute through a fellowship to OS.
Keywords:
Bacterial degradation
;
Dissolved organic matter (DOM)
;
Phosphonate metabolism
;
C-P lyase
;
Methane
;
Ethylene
;
Oligotrophic conditions
Repository Name:
Woods Hole Open Access Server
Type:
Article
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