Aquiflexum lacus sp. nov., isolated from a lake sediment sample

A novel Gram-staining negative, crescent-like or rod-shaped, non-motile bacterium, designated strain CUG 91378( T), was isolated from a sediment sample of Qinghai Lake, Qinghai Province, China. The strain was red-colored, and catalase- and oxidase-positive. Strain CUG 91378( T) was able to grow at 15-37 degrees C (optimum, 28 degrees C), pH 7-9 (pH 7.0) and in the presence of up to 3.0% (w/v) NaCl (0-2%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CUG 91378( T) formed a well-supported monophyletic clade with Aquiflexum balticum DSM 16537( T) (95.4%) and Aquiflexum aquatile Z0201(T) (93.2%). The DNA G + C content of CUG 91378( T) was 39.0%. Low (< 87%) average nucleotide identity (ANI) and (< 26%) digital DNA-DNA hybridization (dDDH) values were observed between strain CUG 91378( T) and its closest species on the phylogenetic trees. The sole respiratory quinone of strain CUG 91378( T) was MK-7. The predominant fatty acids (> 5.0%) were iso-C-15:0 (19.1%), iso-C-16:0 (12.0%), iso-C-16:1 H (10.9%), iso-C-16:0 3OH (9.2%), iso-C-17:0 3OH (7.7%), C-17:1 omega 6c (6.1%) and anteiso-C-15:0 (5.8%). Strain CUG 91378( T) contained as phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and four unidentified lipids (L1, L2, L3 and L4). Based on the data from the current polyphasic study, the isolate represents a novel species of the genus Aquiflexum for which the name Aquiflexum lacus is proposed. The type strain of the proposed new taxon is CUG 91378( T) (= KCTC 62637( T) = CGMCC 1.13988( T)).

Automated summary

A novel Gram-staining negative bacterium, strain CUG 91378(T), isolated from Qinghai Lake in China, was characterized by its red color, catalase- and oxidase-positive properties, and ability to grow under a wide range of temperature, pH, and salt concentration conditions. Phylogenetic analysis indicated that it belongs to the Aquiflexum genus, with the proposed name Aquiflexum lacus.