NEW AEROBIC AMMONIUM-DEPENDENT OBLIGATELY OXALOTROPHIC BACTERIA - DESCRIPTION OF AMMONIPHILUS-OXALATICUS GEN. NOV., SP. NOV. AND AMMONIPHILUS-OXALIVORANS GEN. NOV., SP. NOV

The genus Ammoniphilus is proposed for aerobic endospore-forming Gram- variable rod-shaped bacteria, which are ammonium-dependent, obligately oxalotrophic and haloalkalitolerant, oxidase-and catalase-positive, m esophilic and motile by peritrichous flagella. Cell wall contained two electron-dense layers. The external layer consists of a chain of elec tron-dense granules morphologically resembling the cellulosomes of Clo stridium thermocellum. Two species are described, Ammoniphilus oxalati cus gen. nov., sp, nov. and Ammoniphilus oxalivorans gen. nov., sp, no v. The type strains of these species are strains RAOx-1 (= DSM 11538) and RAOx-FS (= DSM 11537), respectively. Ammoniphilus strains were iso lated from the rhizosphere of sorrel (Rumex acetosa) and from decaying wood. The strains require a high concentration of ammonium ions and u se oxalate as the sole organic source of carbon and energy for growth; no growth factors were required. Growth occurred at ph 6.8-9.5. The o ptimum temperature and ph for growth were 28-30 degrees C and 8.0-8.5. All strains grew in a saturated solution of ammonium oxalate, and tol erated 3% NaCl. Whole-cell hydrolysates contain meso-diaminopimelic ac id and glucose. The menaquinone of the strains was MK 7, and the major cellular fatty acids were 12-methyl tetradecanoic, cis-hexadec-9-enoi c and hexadecanoic acids. The G+C content of the DNA was 45-46 mol% fo r A. oxalaticus and 42 mol % for A. oxalivorans. The almost complete 1 6S rDNA sequence of three strains of the two species of Ammoniphilus s hows that the genus falls into the radiation of the Clostridium-Bacill us subphylum of Grampositive bacteria. The closest phylogenetic neighb our of Ammoniphilus is Oxalophagus oxalicus. The DNA-DNA hybridization value between strains RAOx-1 and RAOx-FS was 39.7 %.