Isolation and Characterization of Bacteria That Degrade Phosphonates in Marine Dissolved Organic Matter.
Isolation and Characterization of Bacteria That Degrade Phosphonates in Marine Dissolved Organic Matter.
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DOI：
10.3389/fmicb.2017.01786
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发表时间：
2017
影响因子：
5.2
通讯作者：
DeLong EF
中科院分区：
文献类型：
--
作者：
Sosa OA;Repeta DJ;Ferrón S;Bryant JA;Mende DR;Karl DM;DeLong EF
半挥发性溶解有机物（DOM）在少营养海洋环流的表层水中积累，并在季节到年的时间尺度上翻转。DOM的储存库是海洋微生物群落碳、能量和营养物质的重要来源，但微生物的身份和DOM循环背后的生化途径在很大程度上仍不清楚。在这项研究中，我们描述了从夏威夷附近的北太平洋亚热带环流（NPSG）分离出来的细菌，它们能够降解与高分子量溶解有机物（HMWDOM）相关的磷酸盐，这代表了半不稳定DOM的很大一部分。我们用从NPSG地表水中收集的HMWDOM和富含含烷基膦酸酯多糖的纯化HMWDOM进行了稀释至消光培养。hmwdom修饰的培养物富集于与亚硫酸盐杆菌和海洋螺科烃类降解细菌密切相关的玫瑰杆菌分离株中，其中许多编码膦酸盐降解途径。编码C-P裂解酶的亚硫酸盐杆菌培养物能够分解甲基膦酸盐和2-羟乙基膦酸盐，以及在天然HMWDOM多糖中发现的这些膦酸盐的酯，分别产生甲烷和乙烯，以获得磷。相反，这些以HMWDOM多糖为碳源的分离株的生长并没有支持细胞产量的强劲增长，这表明HMWDOM中的组成碳水化合物并不容易被这些单个分离株所利用。我们假设HMWDOM多糖的完全再矿化需要更复杂的微生物种间相互作用。海洋多糖中磷酸盐酯和其他常见取代物的降解可能是海洋DOM转化的关键步骤。
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.