Different Types of Diatom-Derived Extracellular Polymeric Substances Drive Changes in Heterotrophic Bacterial Communities from Intertidal Sediments.
Different Types of Diatom-Derived Extracellular Polymeric Substances Drive Changes in Heterotrophic Bacterial Communities from Intertidal Sediments.
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DOI：
10.3389/fmicb.2017.00245
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发表时间：
2017
影响因子：
5.2
通讯作者：
Underwood GJ
中科院分区：
文献类型：
--
作者：
Bohórquez J;McGenity TJ;Papaspyrou S;García-Robledo E;Corzo A;Underwood GJ
潮间带区域支持广泛的生物膜。这种微植物底栖（MPB）硅藻渗出大量的胞外聚合物（EPS），其包括多糖、糖蛋白和其他生物聚合物，其代表大量的碳库。然而，不同EPS组分的降解速率，以及它们如何在沉积物中形成异养群落，还没有很好的理解。一个好氧的泥滩沉积物泥浆实验进行了在黑暗中与两个不同的EPS碳源，从一个占主导地位的生物膜：胶体EPS（cEPS）和更复杂的热碳酸氢盐提取的EPS。在9天内测定的三种沉积物组分[溶解有机碳（DOC）、总碳水化合物（TCHO）和（cEPS）]的降解速率常数在胶体EPS浆料中（0.105-0.123 d−1）通常高于热碳酸氢盐提取的EPS浆料（0.060-0.096 d−1）。添加热碳酸氢盐EPS导致溶解氮和磷在实验结束时大幅增加，表明更复杂的EPS是再生无机营养盐的重要来源。微生物生物量在9天内增加了约4-6倍，细菌16 S rRNA基因的焦磷酸测序显示，与不添加EPS的对照相比，添加两种类型的EPS极大地改变了细菌群落组成（从0到9天）。拟杆菌（特别是韧杆菌）和疣微菌在热碳酸氢盐EPS和胶体EPS治疗的相对丰度显着增加。EPS组分对碳损失率、营养物再生和微生物群落组装的这些差异性影响提高了我们对海岸沉积物碳循环的理解，并证明了不同微生物群在处理这一丰富的有机碳库中的重要性。
Intertidal areas support extensive diatom-rich biofilms. Such microphytobenthic (MPB) diatoms exude large quantities of extracellular polymeric substances (EPS) comprising polysaccharides, glycoproteins and other biopolymers, which represent a substantial carbon pool. However, degradation rates of different EPS components, and how they shape heterotrophic communities in sediments, are not well understood. An aerobic mudflat-sediment slurry experiment was performed in the dark with two different EPS carbon sources from a diatom-dominated biofilm: colloidal EPS (cEPS) and the more complex hot-bicarbonate-extracted EPS. Degradation rate constants determined over 9 days for three sediment fractions [dissolved organic carbon (DOC), total carbohydrates (TCHO), and (cEPS)] were generally higher in the colloidal-EPS slurries (0.105–0.123 d−1) compared with the hot-bicarbonate-extracted-EPS slurries (0.060–0.096 d−1). Addition of hot-bicarbonate-EPS resulted in large increases in dissolved nitrogen and phosphorous by the end of the experiment, indicating that the more complex EPS is an important source of regenerated inorganic nutrients. Microbial biomass increased ~4–6-fold over 9 days, and pyrosequencing of bacterial 16S rRNA genes revealed that the addition of both types of EPS greatly altered the bacterial community composition (from 0 to 9 days) compared to a control with no added EPS. Bacteroidetes (especially Tenacibaculum) and Verrucomicrobia increased significantly in relative abundance in both the hot-bicarbonate-EPS and colloidal-EPS treatments. These differential effects of EPS fractions on carbon-loss rates, nutrient regeneration and microbial community assembly improve our understanding of coastal-sediment carbon cycling and demonstrate the importance of diverse microbiota in processing this abundant pool of organic carbon.