title: Distribution and diversity of symbiotic thermophiles, Symbiobacterium thermophilum and related bacteria, in natural environments.
abstract: Symbiobacterium thermophilum is a tryptophanase-positive thermophile which shows normal growth only in coculture with its supporting bacteria. Analysis of the 16S rRNA gene (rDNA) indicated that the bacterium belongs to a novel phylogenetic branch at the outermost position of the gram-positive bacterial group without clustering to any other known genus. Here we describe the distribution and diversity of S. thermophilum and related bacteria in the environment. Thermostable tryptophanase activity and amplification of the specific 16S rDNA fragment were effectively employed to detect the presence of Symbiobacterium. Enrichment with kanamycin raised detection sensitivity. Mixed cultures of thermophiles containing Symbiobacterium species were frequently obtained from compost, soil, animal feces, and contents in the intestinal tracts, as well as feeds. Phylogenetic analysis and denaturing gradient gel electrophoresis of the specific 16S rDNA amplicons revealed a diversity of this group of bacteria in the environment.
authors.affiliation: Department of Applied Biological Sciences, Nihon University, Fujisawa, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ueda
authors.forename: M
authors.initials: M
authors.lastname: Ohno
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Nara
authors.forename: Y
authors.initials: Y
authors.lastname: Mori
authors.forename: M
authors.initials: M
authors.lastname: Shimada
authors.forename: M
authors.initials: M
authors.lastname: Hayashi
authors.forename: H
authors.initials: H
authors.lastname: Oida
authors.forename: Y
authors.initials: Y
authors.lastname: Terashima
authors.forename: M
authors.initials: M
authors.lastname: Nagata
authors.forename: T
authors.initials: T
authors.lastname: Beppu
mesh_terms: D000818:Animals; D002417:Cattle; D003470:Culture Media / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D004783:Environmental Microbiology; D020459:Genes, rRNA / Q000235:genetics; D014644:Genetic Variation; D006094:Gram-Positive Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D007612:Kanamycin; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis; D013696:Temperature; D014368:Tryptophanase / Q000378:metabolism
chemical_list: D003470:Culture Media; D012336:RNA, Ribosomal, 16S; D007612:Kanamycin; D014368:Tryptophanase