Nitrolancea hollandica gen. nov., sp nov., a chemolithoautotrophic nitrite-oxidizing bacterium isolated from a bioreactor belonging to the phylum Chloroflexi

A novel nitrite-oxidizing bacterium (NOB), strain Lb ^T, was isolated from a nitrifying bioreactor with a high loading of ammonium bicarbonate in a mineral medium with nitrite as the energy source. The cells were oval (lancet-shaped) rods with pointed edges, non-motile, Gram-positive (by staining and from the cell wall structure) and non-spore-forming. Strain Lb ^T was an obligately aerobic, chemolitoautotrophic NOB, utilizing nitrite or formate as the energy source and CO ₂ as the carbon source. Ammonium served as the only source of assimilated nitrogen. Growth with nitrite was optimal at pH 6.8-7.5 and at 40 °C (maximum 46 °C). The membrane lipids consisted of C ₂₀ alkyl 1,2-diols with the dominant fatty acids being 10MeC ₁₈ and C _{18: 1ω9}. The peptidoglycan lacked meso-DAP but contained ornithine and lysine. The dominant lipoquinone was MK-8. Phylogenetic analyses of the 16s rRNA gene sequence placed strain Lb ^T into the class Thermomicrobia of the phylum Chloroflexi with Sphaerobacter thermophilus as the closest relative. On the basis of physiological and phylogenetic data, it is proposed that strain Lb ^Trepresents a novel species of a new genus, with the suggested name Nitrolancea hollandica gen. nov., sp. nov. The type strain of the type species is Lb ^T (= DSM 23161 ^T = UNIQEM U798 ^T).