Tindallia californiensis sp. nov., a new anaerobic, haloalkaliphilic, spore-forming acetogen isolated from Mono Lake in California

A novel extremely haloalkaliphilic, strictly anaerobic, acetogenic bacterium strain APO was isolated from sediments of the athalassic, meromictic, alkaline Mono Lake in California. The Gram-positive, spore-forming, slightly curved rods with sizes 0.55–0.7×1.7–3.0 μm were motile by a single laterally attached flagellum. Strain APO was mesophilic (range 10–48 °C, optimum of 37 °C); halophilic (NaCl range 1–20% (w/v) with optimum of 3–5% (w/v), and alkaliphilic (pH range 8.0–10.5, optimum 9.5). The novel isolate required sodium ions in the medium. Strain APO was an organotroph with a fermentative type of metabolism and used the substrates peptone, bacto-tryptone, casamino acid, yeast extract, l-serine, l-lysine, l-histidine, l-arginine, and pyruvate. The new isolate performed the Stickland reaction with the following amino acid pairs: proline + alanine, glycine + alanine, and tryptophan + valine. The main end product of growth was acetate. High activity of CO dehydrogenase and hydrogenase indicated the presence of a homoacetogenic, non-cycling acetyl-CoA pathway. Strain APO was resistant to kanamycin but sensitive to chloramphenicol, tetracycline, and gentamycin. The G+C content of the genomic DNA was 44.4 mol% (by HPLC method). The sequence of the 16S rRNA gene of strain APO possessed 98.2% similarity with the sequence from Tindallia magadiensis Z-7934, but the DNA-DNA hybridization value between these organisms was only 55%. On the basis of these physiological and molecular properties, strain APO is proposed to be a novel species of the genus Tindallia with the name Tindallia californiensis sp. nov., (type strain APO = ATCC BAA-393 = DSM 14871).