Souza-Egipsy Virginia, González-Toril Elena, Zettler Erik, Amaral-Zettler Linda, Aguilera Angeles, Amils Ricardo
Center of Astrobiology, INTA-CSIC, Torrejón de Ardoz, Spain.
Int Microbiol. 2008 Dec;11(4):251-60. doi: 10.2436/20.1501.01.69.
Four algal photosynthetic biofilms were collected from the Río Tinto (SW Spain) at four localities: AG, Euglena and Pinnularia biofilms; ANG, Chlorella and Pinnularia biofilms; RI, Cyanidium and Dunaliella biofilms; and CEM, Cyanidium, Euglena and Pinnularia biofilms. Community composition and structure were studied by a polyphasic approach consisting of 16S rRNA analysis, scanning electron microscopy by back-scattered electron detection mode (SEM-BSE), and fluorescence in-situ hybridization (FISH). Acidophilic prokaryotes associated with algal photosynthetic biofilms included sequences related to the Alpha-, Beta-, and Gammaproteobacteria (phylum Proteobacteria) and to the phyla Nitrospira, Actinobacteria, Acidobacteria and Firmicutes. Sequences from the Archaea domain were also identified. No more than seven distinct lineages were detected in any biofilm, except for those from RI, which contained fewer groups of Bacteria. Prokaryotic communities of the thinnest algal photosynthetic biofilms (-100 microm) were more related to those in the water column, including Leptospirillum populations. In general, thick biofilms (200 microm) generate microniches that could facilitate the development of less-adapted microorganisms (coming from the surrounding environment) to extreme conditions, thus resulting in a more diverse prokaryotic biofilm.
AG，裸藻和羽纹藻生物膜；ANG，小球藻和羽纹藻生物膜；RI，蓝纤维藻和杜氏藻生物膜；以及CEM，蓝纤维藻、裸藻和羽纹藻生物膜。通过多相方法研究群落组成和结构，该方法包括16S rRNA分析、背散射电子检测模式扫描电子显微镜（SEM-BSE）和荧光原位杂交（FISH）。与藻类光合生物膜相关的嗜酸原核生物包括与α-、β-和γ-变形菌门（变形菌门）以及硝化螺旋菌门、放线菌门、酸杆菌门和厚壁菌门相关的序列。还鉴定出了古菌域的序列。除了来自RI的生物膜，其细菌类群较少外，在任何生物膜中检测到的不同谱系不超过七个。最薄的藻类光合生物膜（-100微米）的原核生物群落与水柱中的原核生物群落更相关，包括钩端螺旋菌种群。一般来说，厚生物膜（200微米）会产生微生境，这可能有助于适应性较差的微生物（来自周围环境）在极端条件下生长，从而形成更多样化的原核生物膜。
