PT Unknown AU Tank, M TI Ecological and phylogenetic studies on purple sulfur bacteria based on their pufLM genes of the photosynthetic reaction center PY 2010 PU Christian-Albrechts-Universität zu Kiel WP https://macau.uni-kiel.de/receive/diss_mods_00005589 LA en DE pufL; pufM; pufLM; photosynthetic reaction center; purple sulfur bacteria; functional genes; evolution; Phylogeny; photosynthetisches Reaktionszentrum; Schwefelpurpurbakterien; funktionelle Gene; Phylogenie AB In this thesis pufLM genes were tested for their suitability as phylogenetic markers for purple sulfur bacteria (PSB) and applied in environmental community studies as well as in polyphasic taxonomy. pufLM genes encode for the light and medium subunit of the photosynthetic reaction center type II proteins exclusively present in the polyphyletic group of anoxygenic phototrophic purple bacteria and Chloroflexaceae. Congruency between 16S rRNA gene and pufLM phylogeny was obtained in this study for PSB which allows the identification of phototrophic purple bacteria based on their pufLM gene sequence exclusively. It is concluded that horizontal gene transfer of pufLM genes within the PSB is highly unlikely. Additional phylogenetic calculations including representatives of purple nonsulfur bacteria (PNSB) and aerobic anoxygenic phototrophic Proteobacteria (AAPB) showed a clear separation of the phototrophic purple Alpha-, Beta-, and Gammaproteobacteria, which is antithetic to all pufLM based phylogenetic studies published before and indicates a suitability of pufLM as a phylogenetic marker for PNSB, AAPB and Chloroflexaceae as well. In addition, signature amino acids and nucleotides were revealed for different PSB groups and proved to be a helpful tool in polyphasic taxonomy. The modified primer pair was successfully applied to environmental communities of phototrophic purple bacteria from a Baltic Sea coastal lagoon and a Chilean salt lake. pufLM was further used to monitor changes in community composition at different salinity and temperature conditions via RFLP and cloning experiments. The Baltic Sea coastal lagoon inhabited a highly diverse PSB community of mesophilic salt-tolerant and salt-dependent Chromatiaceae species, co-existing with PNSB and alpha- and gammaproteobacterial AAPB. They were demonstrated to be specifically well adapted to the naturally occurring salinity and temperature variations. However, at elevated temperatures (>40°C) PSB diversity was distinctively lower and the community compostion completely changed. The Chilean Salar de Atacama typifies a slightly alkaline hypersaline environment and was inhabited by a diverse set of so far unidentified phototrophic bacteria, some typical moderately to extremely halophilic PSB of the Chromatiaceae and Ectothiorhodospiraceae and gammaproteobacterial AAPB. The molecular functional gene approach quarried a high diversity of so far unidentified bacteria. Equally, the presence of cultured and uncultured possible new genera and species of PSB was demonstrated indicating that neither the uncultured nor the cultivable diversity of PSB is fully covered, yet. PI Kiel ER