Thermus thermamylovorans sp. nov., isolated from a hot spring.

Abstract

A novel thermophilic bacterium, designated CFH 72773T was isolated from the enrichment of a Jinze hot spring sample which was collected from Dientan town, Tengchong county, Yunnan province, south-western PR China. Cells were Gram-stain-negative, aerobic, non-motile, rod-shaped and non-sporulating. The taxonomic position of the strain was investigated by using a polyphasic approach. Growth occurred at 37-75 °C, pH 6.0-8.0 and with 0-2.0 % (w/v) NaCl. Comparison of the 16S rRNA gene sequences indicated the strain represented a member of the genus Thermus and showed close relationships to the type strains Thermus caliditerrae YIM 77925T (96.3 % similarity) and Thermus igniterrae RF-4T (96.2 % similarity). The whole genome of CFH 72773T consisted of 2.25 Mbp and the DNA G+C content was 69.5 mol%. A total of 2262 genes, including a variety of enzymes for chemolithotrophy and anerobic respiration, were predicted. The strain had a unique negative oxidase activity and could hydrolyze starch at high temperature. Furthermore, various genes related to methane, sulfur, fumarate and nitrate metabolism were found, all these indicated that it is worth studying the novel strain. The predominant menaquinone is MK-8. The predominant cellular fatty acids included iso-C15 : 0, iso-C16 : 0 and iso-C17 : 0. The major polar lipids were comprised of aminophospholipid, glycolipid and two phospholipids. On the basis of low ANI values, different phenotypic and chemotaxonomic characters and phylogenetic analysis, we made a proposal that strain CFH 72773T represents a novel member of the genus Thermus, for which the name Thermus thermamylovorans sp. nov. is proposed. The type strain is CFH 72773T (=CCTCC AB2018244T=KCTC 43129T).