The genus Limnohabitans (Comamonadaceae, Betaproteobacteria) is a common and a highly active component of freshwater bacterioplanktonic communities. To date, the genus has been considered to contain only heterotrophic species. In this study, we detected the photosynthesis genes pufLM and bchY in 28 of 46 strains from three Limnohabitans lineages. The pufM sequences obtained are very closely related to environmental pufM sequences detected in various freshwater habitats, indicating the ubiquity and potential importance of photoheterotrophic Limnohabitans in nature. Additionally, we sequenced and analyzed the genomes of 5 potentially photoheterotrophic Limnohabitans strains, to gain further insights into their phototrophic capacity. The structure of the photosynthesis gene cluster turned out to be highly conserved within the genus Limnohabitans and also among all potentially photosynthetic Betaproteobacteria strains. The expression of photosynthetic complexes was detected in a culture of Limnohabitans planktonicus II-D5T using spectroscopic and pigment analyses. This was further verified by a novel combination of infrared microscopy and fluorescent in situ hybridization.IMPORTANCE The data presented document that the capacity to perform anoxygenic photosynthesis is common among the members of the genus Limnohabitans, indicating that they may have a novel role in freshwater habitats.

• Klíčová slova
• FISH, IR microscopy, Limnohabitans, bacteriochlorophyll, bchY, freshwater Betaproteobacteria, photosynthetic bacteria, pufM,
• MeSH
• aerobióza MeSH
• bakteriální geny fyziologie   MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• Comamonadaceae genetika   metabolismus   MeSH
• fotosyntéza genetika   MeSH
• fylogeneze MeSH
• multigenová rodina fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny MeSH

Photosynthetic bacteria emerged on Earth more than 3 Gyr ago. To date, despite a long evolutionary history, species containing (bacterio)chlorophyll-based reaction centers have been reported in only 6 out of more than 30 formally described bacterial phyla: Cyanobacteria, Proteobacteria, Chlorobi, Chloroflexi, Firmicutes, and Acidobacteria. Here we describe a bacteriochlorophyll a-producing isolate AP64 that belongs to the poorly characterized phylum Gemmatimonadetes. This red-pigmented semiaerobic strain was isolated from a freshwater lake in the western Gobi Desert. It contains fully functional type 2 (pheophytin-quinone) photosynthetic reaction centers but does not assimilate inorganic carbon, suggesting that it performs a photoheterotrophic lifestyle. Full genome sequencing revealed the presence of a 42.3-kb-long photosynthesis gene cluster (PGC) in its genome. The organization and phylogeny of its photosynthesis genes suggests an ancient acquisition of PGC via horizontal transfer from purple phototrophic bacteria. The data presented here document that Gemmatimonadetes is the seventh bacterial phylum containing (bacterio)chlorophyll-based phototrophic species. To our knowledge, these data provide the first evidence that (bacterio)chlorophyll-based phototrophy can be transferred between distant bacterial phyla, providing new insights into the evolution of bacterial photosynthesis.

• Klíčová slova
• aerobic photoheterotroph, anoxygenic photosynthesis, bacterial pigments, fluorescence imaging system, horizontal gene transfer,
• MeSH
• Bacteria cytologie   genetika   metabolismus   MeSH
• druhová specificita MeSH
• fluorescenční mikroskopie MeSH
• fluorometrie MeSH
• fotosystém II - proteinový komplex genetika   metabolismus   MeSH
• fylogeneze * MeSH
• jezera mikrobiologie   MeSH
• modely genetické MeSH
• molekulární sekvence - údaje MeSH
• pravděpodobnostní funkce MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• spektrální analýza MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Čína MeSH
• Názvy látek
• fotosystém II - proteinový komplex MeSH
• RNA ribozomální 16S MeSH