title: Functional type 2 photosynthetic reaction centers found in the rare bacterial phylum Gemmatimonadetes.
abstract: 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.
authors.affiliation: Department of Phototrophic Microorganisms, Institute of Microbiology CAS, 37981 Třeboň, Czech Republic;
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Institute for Applied and Environmental Microbiology, College of Life Sciences, Inner Mongolia Agricultural University, Huhhot 010018, China; and.
authors.forename: Fuying
authors.initials: F
authors.lastname: Feng
authors.affiliation: Department of Phototrophic Microorganisms, Institute of Microbiology CAS, 37981 Třeboň, Czech Republic;
authors.forename: Hana
authors.initials: H
authors.lastname: Medová
authors.affiliation: Department of Phototrophic Microorganisms, Institute of Microbiology CAS, 37981 Třeboň, Czech Republic;
authors.forename: Jason
authors.initials: J
authors.lastname: Dean
authors.affiliation: Department of Phototrophic Microorganisms, Institute of Microbiology CAS, 37981 Třeboň, Czech Republic;Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic koblizek@alga.cz.
authors.forename: Michal
authors.initials: M
authors.lastname: Koblížek
mesh_terms: D001419:Bacteria / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002681:China; D016000:Cluster Analysis; D005470:Fluorometry; D060106:Lakes / Q000382:microbiology*; D016013:Likelihood Functions; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D045332:Photosystem II Protein Complex / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013057:Spectrum Analysis
chemical_list: D045332:Photosystem II Protein Complex; D012336:RNA, Ribosomal, 16S
keywords: aerobic photoheterotroph; anoxygenic photosynthesis; bacterial pigments; fluorescence imaging system; horizontal gene transfer