Kineothrix sedimenti sp. nov., a 3-hydroxybutyrate-producing bacterium isolated from sediment of the meromictic Lake Pavin

An anaerobic, spore-forming, 3-hydroxybutyrate (3-HB)-producing bacterium, strain IPX_CK^T, was isolated from sediment of a meromictic lake located in Massif Central (France). Cells were rods, forming filamentous chains which were observed moving under the microscope. Strain IPX_CK^T utilized a wide variety of carbohydrates, but not raffinose, rhamnose and starch. Hydrogen (H₂), 3-HB, acetate and ethanol were the main fermentative end-products from growth in medium containing glucose. Strain IPX_CK^T grew optimally at 37 °C and pH 7. Its closest phylogenetic relative was <i>Kineothrix alysoides</i> (16S rRNA gene sequence identity 98.7%, <i>is</i>DDH 34.6%, ANIb 87.4%). The genomic DNA G+C content was 43.0 mol%. As for <i>K. alysoides</i>, whole-genome sequencing suggested that strain IPX_CK^T is capable of fixing nitrogen (N₂). However, strain IPX_CK^T carried a five-<i>nif</i>-gene-set (<i>nifHDKEB</i>), not present in <i>K. alysoides</i>. Genome sequence also showed a high number of encoded chemotaxis receptors (42 genes, the second highest in the family <i>Lachnospiraceae</i> after <i>K. alysoides</i>). Based on phenotypic, genomic, phylogenetic and chemotaxonomic analyses, it is proposed that a novel species, <i>Kineothrix sedimenti</i> sp. nov., be created, with strain IPX_CK^T (DSM 118044^T, CIP 112511^T) as the type strain.