The study of phylogenetic evolution of phototrophic bacteria

Research Project

Project/Area Number	06640896
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	系統・分類
Research Institution	The University of Tokyo
Principal Investigator	KAWASAKI Hiroko Institute of Molecular and Cellular Biosciences, The University of Tokyo, Research Associate, 分子細胞生物学研究所, 助手 (30251482)
Co-Investigator(Kenkyū-buntansha)	SUGIYAMA Junta Institute of Molecular and Cellular Biosciences, The University of Tokyo, Profes, 分子細胞生物学研究所, 教授 (80142256)
Project Period (FY)	1994 – 1995
Project Status	Completed (Fiscal Year 1995)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords	Phototrophic bacteria / 16S rRNA / 16S rDNA / phylogeny / 16S rRNA
Research Abstract	The phylogenetic structure of purple non-sulfur bacteria in the Proteobacteria alpha group was elucidated by the comparative analysis of 16S rRNA sequences including isolated strains and non-phototrophic bacteria.The phylogenetic diversity within the phototrophic bacteria was evident from the very wide range of the homology values and the topology of the phylogenetic tree.There are three major subgroup of phototrophic bacteria in Proteobacteria alpha group. Proteobacteria alpha-1 subgroup was constructed by the vibrioid and/or spiral shaped phototrophic bacteria and non-phototrophic bacteria. The bootstrapped neighbor-joining tree placed the spirillum taxa assigned to Rhodospirillum, Rhodocista, Aquaspirillum, Oceanospirillum, Azospirillum, and Magnetospirillum of the Proteobacteria in seven clusters of alpha Proteobacteria separately from other shapes of bacteria. Our molecular phylogenetic analysis suggested the spirilla are very diverse in the alpha Proteobacteria. Phylogenetic gaps … More exist in marine spirilla, spirilla from freshwater and spirilla living in soil in spite of no gaps in bacteria of other shapes. Photosynthetic and magnetotactic bacteria are not monophyletic. In these taxa, photosynthesis and magnetotaxis do not appear as important taxonomic characters at the generic level. New phototrophic bacteria containing bacteriochlorophyll b were isolated in Thai Land.The isolates were most related to Rhodopseudomonas sulfoviridis. The phototrophic bacteria which are ovoid shaped bacteria containing Bchl b in the purple non-sulfur bacteria were constructed one lineage separately from other phototrophic bacteria. In the Proteobacteria alpha-3, there are two genera of phototrophic bacteria which are Rhodobacter ; living in freshwater or terrestrial environment, and Rhodovulum ; marine phototrophic bacteria. Some of our isolates from marine water were related to Rhodobacter species phylogeneticaly. Our study suggested the the requirement of NaCl don't appear as key character of generic level in this subgroup. We found the new species in three subgroup during this study. It was suggested that there are many kind of phototrophic species which are not found yet in the environments. The classification of the phototrophic bacteria should be rearrange with non-phototrophic bacteria. Many new phototrophic isolates will supported the new classification of Proteobacteria. Less