A novel thermophilic, hydrogen-oxidizing bacterium, designated strain CP.B2T, was isolated from a terrestrial hot spring in Waiotapu, New Zealand. Cells were motile, slightly rod-shaped, non-spore-forming and Gram-negative. Isolate CP.B2T was an obligate chemolithotroph, growing by utilizing H2 as electron donor and O2 as corresponding electron acceptor. Elemental sulfur (S0) or thiosulfate () was essential for growth. Microbial growth occurred under microaerophilic conditions in 1.0–10.0 % (v/v) O2 [optimum 4–8 % (v/v) O2], between 45 and 75 °C (optimum 70 °C) and at pH values of 4.8–5.8 (optimum pH 5.4). The DNA G+C content was 29.3 mol%. 16S rRNA gene sequence analysis demonstrated that strain CP.B2T belonged to the order Aquificales, with a close phylogenetic relationship to Sulfurihydrogenibium azorense (94 % sequence similarity to the type strain). However, genotypic and metabolic characteristics differentiated the novel isolate from previously described genera of the Aquificales. Therefore, CP.B2T represents a novel species in a new genus, for which the name Venenivibrio stagnispumantis gen. nov., sp. nov. is proposed. The type strain of Venenivibrio stagnispumantis is CP.B2T (=JCM 14244T =DSM 18763T).
Samples from plants of Cassia italica exhibiting typical witches'-broom symptoms (Cassia witches'-broom; CWB) were examined for the presence of plant pathogenic phytoplasmas by PCR amplification using universal phytoplasma primers. All affected plants yielded positive results. RFLP analyses of rRNA gene products indicated that the phytoplasmas detected were different from those described previously. Phylogenetic analysis of 16S rRNA gene sequences confirmed that CWB represents a distinct lineage and shares a common ancestor with ‘Candidatus Phytoplasma phoenicium’. Molecular comparison revealed that the 16S rRNA gene sequences of the four CWB strains (IM-1, IM-2, IM-3 and IM-4) identified in symptomatic C. italica samples were nearly identical (99.6–100 % similarity). The closest relatives were members of the pigeon pea witches'-broom phytoplasma ribosomal group (16SrIX; 95–97 % sequence similarity). On the basis of unique 16S rRNA gene sequences and biological properties, the phytoplasma associated with witches'-broom of C. italica in Oman represents a coherent but discrete novel phytoplasma, ‘Candidatus Phytoplasma omanense’, with GenBank/DDBJ/EMBL accession number EF666051 representing the reference strain.