Structural and functional analysis of a microbial mat ecosystem from a unique permanent hypersaline inland lake: 'La Salada de Chiprana' (NE Spain)
Structural and functional analysis of a microbial mat ecosystem from a unique permanent hypersaline inland lake: 'La Salada de Chiprana' (NE Spain)
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DOI：
10.1016/s0168-6496(02)00464-6
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发表时间：
2003-05-15
影响因子：
4.2
通讯作者：
De Beer, D
中科院分区：
文献类型：
--
作者：
Jonkers, HM;Ludwig, R;De Beer, D
对西欧唯一的永久性高盐度天然内陆湖--西班牙东北部的La Salada de Chiprana湖的底栖微生物群落进行了结构和功能分析。湖水的离子组成具有较高的镁和硫酸盐含量，采样时镁和硫酸盐含量分别为0.35和0.5M，总盐度为78g1(-1)。通过显微镜、高效液相色谱(HPLC)色素分析和研究不同功能基团的可培养细菌，分析了群落组成。因此，变性梯度凝胶电泳法(DGGE)被应用于最可能数(MPN)稀释培养。显微镜观察发现，一层薄薄的类绿藻细菌覆盖在以蓝藻为主的各种层上，每个层具有不同的形态类型。对不同垫层MPN稀释培养物的DGGE分析表明，存在各种类型的产氧光营养细菌、好氧异养细菌、无色硫磺还原细菌和硫酸盐还原细菌。进一步对垫子的功能进行了研究，重点关注了氧气初级生产与碳在微生物群落中的流动之间的关系。应用微传感器技术、孔隙水和底泥光色分析技术，估算了光合作用速率、有机碳(In)孔隙水浓度的日动态和光养生物的迁移行为。奇普拉纳微生物垫在白天和晚上都会产生溶解有机碳(DOC)。据估计，14%的总光合作用产物和49%的净光合作用产物以低分子质量脂肪酸的形式扩散到垫子外，尽管这些化合物只占总DOC池的2%。从微生物垫子到水柱的溶解脂肪酸的高通量可以解释为什么在这个系统中，类绿藻细菌在蓝细菌层的顶部繁殖，因为这些光异养细菌更好地生长在有机光营养渗出物上。此外，这也可以解释为什么在完全氧化的沉积物表层发现了大量活的硫酸盐还原细菌。由于有充足的有机底物，这些生物显然不必与好氧异养群落成员竞争。此外，DOC的高产量强烈表明，垫子群落的生长受到养分的限制。光显色分析进一步表明，叶绿素a(Chla)及其三个异构体具有互补的深度分布，这表明Chla异构体是对光质量和/或光数量差异的功能性适应，可能是物种特有的。(C)2003年欧洲微生物学会联合会。爱思唯尔科学公司出版。版权所有。
The benthic microbial mat community of the only permanent hypersaline natural inland lake of Western Europe, 'La Salada de Chiprana', northeastern Spain, was structurally and functionally analyzed. The ionic composition of the lake water is characterized by high concentrations of magnesium and sulfate, which were respectively 0.35 and 0.5 M at the time of sampling while the total salinity was 78 g 1(-1). Community composition was analyzed by microscopy, high-performance liquid chromatography (HPLC) pigment analyses and by studying culturable bacteria from different functional groups. Therefore, denaturing gradient gel electrophoresis (DGGE) was applied on most probable number (MPN) dilution cultures. Microscopy revealed that a thin layer of Chloroflexus-like bacteria overlaid various cyanobacteria-dominated layers each characterized by different morphotypes. DGGE analysis of MPN dilution cultures from distinct mat layers showed that various phylotypes of anoxygenic phototrophic, aerobic heterotrophic, colorless sulfur-, and sulfate-reducing bacteria were present. The mats were furthermore functionally studied and attention was focussed on the relationship between oxygenic primary production and the flow of carbon through the microbial community. Microsensor techniques, porewater and sediment photopigment analysis were applied in order to estimate oxygenic photosynthetic rates, daily dynamics of (in)organic carbon porewater concentration and migration behavior of phototrophs. Chiprana microbial mats produced dissolved organic carbon (DOC) both during the day and night. It was estimated that 14% of the mats gross photosynthetic production and 49% of the mats net photosynthetic production diffused out of the mat in the form of low molecular mass fatty acids, although these compounds made up only 2% of the total DOC pool. The high flux of dissolved fatty acids from the microbial mat to the water column may explain why in this system Chloroflexus-like bacteria proliferate on top of the cyanobacterial layers since these photoheterotrophic bacteria grow preferably on organic phototrophic exudates. Furthermore it may also explain why high numbers of viable sulfate-reducing bacteria were found in the fully oxygenated sediment surface layers. These organisms apparently do not have to compete with aerobic heterotrophic community members due to the ample availability of organic substrates. Moreover, the high produciion of DOC strongly indicates that the mat community was nutrient limited in its growth. Photopigment analysis revealed furthermore that chlorophyll a (Chla) and three of its allomeres had a complementary depth distribution what suggests that the Chla allomeres are functional adaptations to differences in light quality and/or quantity and may be species specific. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.