Enzyme activities in the water column and in shallow permeable sediments from the northeastern Gulf of Mexico
Enzyme activities in the water column and in shallow permeable sediments from the northeastern Gulf of Mexico
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DOI：
10.1016/j.ecss.2009.06.018
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发表时间：
2009-09-10
影响因子：
2.8
通讯作者：
Ghobrial, S.
中科院分区：
文献类型：
--
作者：
Arnosti, C.;Ziervogel, K.;Ghobrial, S.
在墨西哥湾东北部的两个地点的水柱和沙地表层沉积物中，研究了启动高分子有机物微生物再矿化的胞外酶的活性。六种荧光标记的多糖在水柱和渗透性沉积物中被迅速降解。这一结果与之前在细粒泥浆为主的环境中进行的研究形成了鲜明对比，在细粒泥浆环境中，与底层沉积物相比，水柱中活跃的酶的谱相当有限。螺旋藻、等鞭金藻和海链藻的提取物也被用来测量其中一个地点的水的水解率。三种浮游生物提取物的水解率与纯化后的多糖的水解率相当。在墨西哥湾东北部两个地点的水柱中观察到的广谱和快速的水解可能是由于沉积物的渗透性。通过沉积物的流体流量足够高，整个1.5米深的水柱可以在几天到两周的时间尺度上过滤沉积物。水在沉积物中的运动也可以将溶解的酶从沉积物输送到水柱中，从而提高光谱和水柱酶活性的速率。沉积物和水柱之间的这种相互作用将允许水柱微生物群落获得高分子量底物，否则这些底物可能无法用作底物。(C)2009爱思唯尔有限公司。保留所有权利。
The activities of extracellular enzymes that initiate the microbial remineralization of high molecular weight organic matter were investigated in the water column and sandy surface sediments at two sites in the northeastern Gulf of Mexico. Six fluorescently labeled polysaccharides were hydrolyzed rapidly in the water column as well as in permeable sediments. This result contrasts with previous studies carried out in environments dominated by fine-grained muds, in which the spectrum of enzymes active in the water column is quite limited compared to that of the underlying sediments. Extracts of Spirulina, Isochrysis, and Thalassiosira were also used to measure hydrolysis rates in water from one of the sites. Rates of hydrolysis of the three plankton extracts were comparable to those of the purified polysaccharides. The broad spectrum and rapid rates of hydrolysis observed in the water column at both sites in the northeastern Gulf of Mexico may be due to the permeable nature of the sediments. Fluid flux through the sediments is sufficiently high that the entire 1.5 m deep water column could filter though the sediments on timescales of a few days to two weeks. Movement of water through sediments may also transport dissolved enzymes from the sediment into the water column, enhancing the spectrum as well as the rate of water column enzymatic activities. Such interaction between the sediments and water column would permit water column microbial communities to access high molecular weight substrates that might otherwise remain unavailable as substrates. (C) 2009 Elsevier Ltd. All rights reserved.