de Brouwer J F C, Wolfstein K, Ruddy G K, Jones T E R, Stal L J
Netherlands Institute of Ecology, Centre for Estuarine and Coastal Ecology, P.O. Box 140, 4400 AC, Yerseke, The Netherlands.
Microb Ecol. 2005 May;49(4):501-12. doi: 10.1007/s00248-004-0020-z. Epub 2005 Jul 29.
The sediment-stabilizing effect of benthic diatoms was investigated in a laboratory setting. Axenic cultures of the benthic diatoms Nitzschia cf. brevissima and Cylindrotheca closterium were inoculated in Petri dishes containing sand and incubated under axenic conditions. By ensuring aseptic routines throughout the experiments, interference from other organisms occurring with diatoms in natural photothrophic biofilms was avoided. This allowed the examination of the role of benthic diatoms in sediment stabilization. Increases in the critical erosion shear stress of the sediment were observed in the presence of both diatom taxa relative to sterile sediment. However, N. cf. brevissima was more effective than C. closterium. Values of critical shear stress in the experimental system were in the same range as those observed in natural biofilms, which indicates that diatoms are important agents for biogenic stabilization. Extracellular carbohydrate contents in the microcosms were similar for both diatom species. However, in the presence of N cf. brevissima, extracellular carbohydrate correlated significantly to critical shear stress, explaining up to 80% of the variation, whereas this was not the case for C. closterium. Therefore, it was concluded that the quantity of extracellular polymeric substances (EPS) alone did not explain the biogenic stabilization. Observed adsorption of EPS to sediment particles depended on the relative amount of uronic acids in the exopolymers. Using fluorescently labeled lectins, confocal laser scanning microscopy showed that EPS secretion by N. cf. brevissima resulted in ordered three-dimensional matrix structures. It is suggested that the structuring of EPS plays an prominent role in the process of biostabilization, and that diatoms such as N. cf. brevissima are actively involved in producing the structure of EPS, whereas others such as C. closterium do not do so to the same extent.
在实验室环境中研究了底栖硅藻的沉积物稳定作用。将底栖硅藻近短菱形藻（Nitzschia cf. brevissima）和梭形筒柱藻（Cylindrotheca closterium）的无菌培养物接种到装有沙子的培养皿中，并在无菌条件下培养。通过在整个实验过程中确保无菌操作程序，避免了自然光合生物膜中与硅藻同时出现的其他生物的干扰。这使得能够研究底栖硅藻在沉积物稳定中的作用。相对于无菌沉积物，在两种硅藻类群存在的情况下，均观察到沉积物的临界侵蚀剪应力增加。然而，近短菱形藻比梭形筒柱藻更有效。实验系统中的临界剪应力值与自然生物膜中观察到的值处于相同范围，这表明硅藻是生物成因稳定的重要因素。两种硅藻物种在微观世界中的细胞外碳水化合物含量相似。然而，在近短菱形藻存在的情况下，细胞外碳水化合物与临界剪应力显著相关，解释了高达80%的变化，而梭形筒柱藻则不然。因此，得出的结论是，仅细胞外聚合物（EPS）的数量并不能解释生物成因稳定。观察到的EPS对沉积物颗粒的吸附取决于胞外聚合物中糖醛酸的相对含量。使用荧光标记的凝集素，共聚焦激光扫描显微镜显示近短菱形藻分泌的EPS形成了有序的三维基质结构。有人认为，EPS的结构化在生物稳定过程中起着重要作用，像近短菱形藻这样的硅藻积极参与EPS结构的形成，而其他如梭形筒柱藻则在相同程度上不参与。
Zotero 插件