title: Heliophilum fasciatum gen. nov. sp. nov. and Heliobacterium gestii sp. nov.: endospore-forming heliobacteria from rice field soils.
abstract: Two new taxa of phototrophic heliobacteria are described: Heliobacterium gestii sp. nov. and Heliophilum fasciatum gen. nov. sp. nov. Both organisms were isolated from dry paddy soils. Cells of H. gestii were motile spirilla; cells of H. fasciatum formed cell bundles that were motile as units. Both organisms produced endospores; H. gestii endospores contained dipicolinic acid and elevated levels of calcium. As with other heliobacteria, bacteriochlorophyll g was produced in both organisms and no intracytoplasmic photosynthetic membranes were observed. Growth of H. gestii and H. fasciatum occurred under both photoheterotrophic and chemotrophic conditions; nitrogen fixation also occurred in both organisms. H. gestii and H. fasciatium showed a phylogenetic relationship to the "low GC" line of gram-positive Bacteria, but H. fasciatum was distinct from H. gestii and all other heliobacteria. The ability of H. gestii and H. fasciatum to form endospores might be a significant ecological advantage for survival in their rice soil habitat.
authors.affiliation: Department of Biology, University of Oslo, Norway.
authors.forename: J G
authors.initials: JG
authors.lastname: Ormerod
authors.forename: L K
authors.initials: LK
authors.lastname: Kimble
authors.forename: T
authors.initials: T
authors.lastname: Nesbakken
authors.forename: Y A
authors.initials: YA
authors.lastname: Torgersen
authors.forename: C R
authors.initials: CR
authors.lastname: Woese
authors.forename: M T
authors.initials: MT
authors.lastname: Madigan
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification / Q000648:ultrastructure*; D018407:Bacterial Physiological Phenomena; D001429:Bacteriochlorophylls / Q000737:chemistry / Q000378:metabolism; D005075:Biological Evolution; D004725:Endospore-Forming Bacteria / Q000145:classification* / Q000302:isolation & purification / Q000502:physiology / Q000648:ultrastructure*; D008854:Microscopy, Electron; D012275:Oryza; D010788:Photosynthesis; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012988:Soil Microbiology; D013171:Spores, Bacterial / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D001429:Bacteriochlorophylls; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S