Dictyobacter halimunensis sp. nov., a new member of the phylum Chloroflexota, from forest soil in a geothermal area

Three Gram-stain-positive aerobic bacteria, characterized by branched mycelia with putative sporangia, were isolated from forest soil inside a decayed bamboo stem from a geothermal area in West Java, Indonesia. The strain S3.2.2.5^T grew at 15-37 °C (optimum 30 °C), at pH 5.0-7.0 (optimum 7.0) and in the presence of 0-1% NaCl (optimum 0%). Strain S3.2.2.5^T was able to hydrolyse cellulose, xylan, starch and skim milk. The cell-wall sugars were composed of xylose and mannose, and the peptidoglycan hydrolysates contained d-glutamic acid, glycine, d-alanine, l-alanine, <i>β</i>-alanine and l-ornithine. The major fatty acids (>10%) were anteiso-C_17:0, iso-C_17:0, C_16:1 2-OH and iso-C_16:1. The major polar lipids were phosphatidylinositol, phosphatidylglycerol, diphosphatidylglycerol, unidentified glycolipids and unidentified phospholipids. The major menaquinone was MK-9 (H₂). The results of the analysis of the phylogenetic tree based on the 16S rRNA gene indicated that these three isolates belong to the genus <i>Dictyobacter</i> and they were most closely related to the type strain of species <i>Dictyobacter aurantiacus</i> S-27^T (97.41-98.00%). The strain S3.2.2.5^T exhibited a genome size of 9.41 Mbp, which was significantly larger than the known <i>Dictyobacter</i> species. The G+C content was 54.3 mol%. The average nucleotide identity (90.77%) and the digital DNA-DNA hybridization values (42.6%) between strain S3.2.2.5^T and <i>D. aurantiacus</i> S-27^T were below the threshold value for species delineation. Based on the phenotypic, chemotaxonomic and molecular characteristics of strain S3.2.2.5^T, a novel species of the genus <i>Dictyobacter</i>, for which the name <i>Dictyobacter halimunensis</i> sp. nov., is proposed. The type strain is S3.2.2.5^T (= UICC B-128^T = CGMCC 1.61913^T = KCTC 43728^T).