Aquiflexum gelatinilyticum sp. nov., isolated from river water

Two Gram-stain-negative, strictly aerobic, rod-shaped, non-motile and non-gliding bacteria, designated as XJ19-10^T and XJ19-11, were isolated from river water in Xinjiang Uygur Autonomous Region, PR China. Cells of these strains were catalase-, oxidase- and gelatinase-positive and contained carotenoids but no flexirubins. Growth occurred at 10-30 °C, pH 7.0-9.0 and with 0-2.5% (w/v) NaCl. On the basis of the results of 16S rRNA gene sequence and genome analyses, the two isolates represented members of the genus Aquiflexum, and the closest relative was Aquiflexum aquatile Z0201^T with 16S rRNA gene sequence pairwise similarities of 97.9-98.1%. Furthermore, the average nucleotide identities and digital DNA-DNA hybridization identities between the two isolates and other relatives were all less than 82.9 and 28.2 %, respectively, all below the species delineation thresholds. The results of pan-genomic analysis indicated that the type strain XJ19-10^T shared 2813 core gene clusters with other three type strains of members of the genus Aquiflexum, as well as having 623 strain-specific clusters. The major polar lipids were phosphatidylethanolamine, phosphatidylcholine, an unidentified aminolipid and unidentified lipids. The predominant fatty acids (>10% of the total contents) were iso-C_{15 : 0}, iso-C_{15 : 1}G, iso-C_{17 : 0} 3-OH and summed feature 9, and MK-7 was the respiratory quinone. On the basis of the results of phenotypic, physiological, chemotaxonomic and genotypic characterization, strains XJ19-10^T and XJ19-11 are considered to represent a novel species, for which the name Aquiflexum gelatinilyticum sp. nov. is proposed. The type strain is XJ19-10^T (=CGMCC 1.19385^T =KCTC 92266^T).