González José M, Fernández-Gómez Beatriz, Fernàndez-Guerra Antoni, Gómez-Consarnau Laura, Sánchez Olga, Coll-Lladó Montserrat, Del Campo Javier, Escudero Lorena, Rodríguez-Martínez Raquel, Alonso-Sáez Laura, Latasa Mikel, Paulsen Ian, Nedashkovskaya Olga, Lekunberri Itziar, Pinhassi Jarone, Pedrós-Alió Carlos
Department of Microbiology and Cell Biology, University of La Laguna, ES-38206 La Laguna, Tenerife, Spain.
Proc Natl Acad Sci U S A. 2008 Jun 24;105(25):8724-9. doi: 10.1073/pnas.0712027105. Epub 2008 Jun 13.
Analysis of marine cyanobacteria and proteobacteria genomes has provided a profound understanding of the life strategies of these organisms and their ecotype differentiation and metabolisms. However, a comparable analysis of the Bacteroidetes, the third major bacterioplankton group, is still lacking. In the present paper, we report on the genome of Polaribacter sp. strain MED152. On the one hand, MED152 contains a substantial number of genes for attachment to surfaces or particles, gliding motility, and polymer degradation. This agrees with the currently assumed life strategy of marine Bacteroidetes. On the other hand, it contains the proteorhodopsin gene, together with a remarkable suite of genes to sense and respond to light, which may provide a survival advantage in the nutrient-poor sun-lit ocean surface when in search of fresh particles to colonize. Furthermore, an increase in CO(2) fixation in the light suggests that the limited central metabolism is complemented by anaplerotic inorganic carbon fixation. This is mediated by a unique combination of membrane transporters and carboxylases. This suggests a dual life strategy that, if confirmed experimentally, would be notably different from what is known of the two other main bacterial groups (the autotrophic cyanobacteria and the heterotrophic proteobacteria) in the surface oceans. The Polaribacter genome provides insights into the physiological capabilities of proteorhodopsin-containing bacteria. The genome will serve as a model to study the cellular and molecular processes in bacteria that express proteorhodopsin, their adaptation to the oceanic environment, and their role in carbon-cycling.
对海洋蓝细菌和变形菌基因组的分析，让人们对这些生物的生存策略、生态型分化及新陈代谢有了深入了解。然而，对于第三大主要浮游细菌类群拟杆菌门的类似分析仍很缺乏。在本文中，我们报告了极地杆菌属菌株MED152的基因组。一方面，MED152含有大量与附着于表面或颗粒、滑行运动及聚合物降解相关的基因。这与目前所假定的海洋拟杆菌门的生存策略相符。另一方面，它含有视紫红质基因，以及一套能感知并响应光的显著基因组合，这在寻找新颗粒进行定殖时，可能为其在贫营养的阳光照射海洋表层提供生存优势。此外，光照下二氧化碳固定的增加表明，有限的中心代谢通过回补性无机碳固定得到补充。这是由膜转运蛋白和羧化酶的独特组合介导的。这表明了一种双重生存策略，如果经实验证实，将与表层海洋中已知的另外两个主要细菌类群（自养蓝细菌和异养变形菌）显著不同。极地杆菌基因组为含视紫红质细菌的生理能力提供了见解。该基因组将作为一个模型，用于研究表达视紫红质的细菌中的细胞和分子过程、它们对海洋环境的适应以及它们在碳循环中的作用。
