Thermus composti sp. nov., isolated from oyster mushroom compost

<jats:p>A Gram-stain-negative, rod-shaped bacterium (strain K-39<jats:sup>T</jats:sup>) was isolated from the thermophilic phase of the composting process for oyster mushroom substrate preparation. The strain grew at 40–80 °C (optimum, 65–75 °C), at pH 5–9 (optimum, pH 7), in media containing up to 1.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain K-39<jats:sup>T</jats:sup> formed a distinct lineage within the genus <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus" xlink:type="simple"> <jats:ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1601/nm.519" xlink:type="simple"> <jats:italic>Thermus</jats:italic> </jats:ext-link> </jats:named-content>. Its closest cultivated relative was <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="species" xlink:type="simple"> <jats:ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1601/nm.14940" xlink:type="simple"> <jats:italic>Thermus islandicus</jats:italic> </jats:ext-link> </jats:named-content> PRI 3838<jats:sup>T</jats:sup> (96.8 % similarity). The DNA G+C content of strain K-39<jats:sup>T</jats:sup> was 71.3 mol%. The new strain could be differentiated from the related taxa by not being able to hydrolyse starch. The predominant fatty acids of strain K-39<jats:sup>T</jats:sup> were iso-C<jats:sub>17 : 0</jats:sub> and anteiso-C<jats:sub>17 : 0</jats:sub>. Strain K-39<jats:sup>T</jats:sup> contained a lower amount of the fatty acid iso-C<jats:sub>15 : 0</jats:sub> as compared to related species of the genus <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus" xlink:type="simple"> <jats:ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1601/nm.519" xlink:type="simple"> <jats:italic>Thermus</jats:italic> </jats:ext-link> </jats:named-content>. The predominant respiratory quinone of the new isolate was menaquinone MK-8. On the basis of a taxonomic study using a polyphasic approach, strain K-39<jats:sup>T</jats:sup> is considered to represent a novel species of the genus <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus" xlink:type="simple"> <jats:ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.1601/nm.519" xlink:type="simple"> <jats:italic>Thermus</jats:italic> </jats:ext-link> </jats:named-content>, for which the name <jats:italic>Thermus composti</jats:italic> sp. nov. is proposed. The type strain is K-39<jats:sup>T</jats:sup> ( = DSM 21686<jats:sup>T</jats:sup> = NCAIM B 02340<jats:sup>T</jats:sup>).</jats:p>