title: Moderately thermophilic nitrifying bacteria from a hot spring of the Baikal rift zone.
abstract: Samples from three hot springs (Alla, Seya and Garga) located in the northeastern part of Baikal rift zone (Buryat Republic, Russia) were screened for the presence of thermophilic nitrifying bacteria. Enrichment cultures were obtained solely from the Garga spring characterized by slightly alkaline water (pH 7.9) and an outlet temperature of 75 degrees C. The enrichment cultures of the ammonia- and nitrite oxidizers grew at temperature ranges of 27-55 and 40-60 degrees C, respectively. The temperature optimum was approximately 50 degrees C for both groups and thus they can be designated as moderate thermophiles. Ammonia oxidizers were identified with classical and immunological techniques. Representatives of the genus Nitrosomonas and Nitrosospira-like bacteria with characteristic vibroid morphology were detected. The latter were characterized by an enlarged periplasmic space, which has not been previously observed in ammonia oxidizers. Electron microscopy, denaturing gradient gel electrophoresis analyses and partial 16S rRNA gene sequencing provided evidence that the nitrite oxidizers were members of the genus Nitrospira.
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Oktyabrya 7/2, Moscow 117312, Russia.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Lebedeva
authors.forename: Mashal
authors.initials: M
authors.lastname: Alawi
authors.forename: Claudia
authors.initials: C
authors.lastname: Fiencke
authors.forename: Bair
authors.initials: B
authors.lastname: Namsaraev
authors.forename: Eberhard
authors.initials: E
authors.lastname: Bock
authors.forename: Eva
authors.initials: E
authors.lastname: Spieck
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D045482:Hot Springs / Q000382:microbiology*; D008854:Microscopy, Electron; D009573:Nitrites / Q000378:metabolism*; D009606:Nitrosomonas / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013696:Temperature
chemical_list: D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D000641:Ammonia