Algoriphagus aurantiacus sp. nov. and Algoriphagus persicinus sp. nov., two novel species isolated from the shore soil of salt lake

Abstract

Six Gram-staining-negative, aerobic, non-motile and rod-shaped bacterial strains, designated as D3-2-R+10^T, C2-6-M1^T, E1-3-M2, D2-2-M3, D2-2-M2 and D2-2-M1, were isolated from the shore soil of LungmuCo Lake in Xizang Autonomous Region, China. The 16S rRNA gene sequence comparisons confirmed that the six isolates belonged to the genus Algoriphagus of the family Cyclobacteriaceae. The 16S rRNA gene sequence of strains D3-2-R+10^T, D2-2-M3, D2-2-M2 and D2-2-M1 exhibited the highest similarities to the type strains of Algoriphagus antarcticus LMG 21980^T(98.1-98.5 %) and Algoriphagus resistens NH1^T (97.9-98.4 %). Meanwhile, the 16S rRNA gene sequence of strains C2-6-M1^T and E1-3-M2 showed the highest similarities to A. antarcticus LMG 21980^T (98.2-98.7%). The average nt identity and digital DNA-DNA hybridization values among strains D3-2-R+10^T and C2-6-M1^T and their most closely related species A. antarcticus LMG 21980^T were all lower than the threshold values for delineating species, indicating that they represent two separate novel species of Algoriphagus. The predominant cellular fatty acids of strains D3-2-R+10^T and C2-6-M1^T included iso-C_{15 : 0}, summed feature 3 (C_{16 : 1} ω7c/C_{16 : 1} ω6c) and summed feature 9 (iso-C_{17 : 1} ω9c/C_{16 : 0} 10-methyl), and the predominant respiratory quinone was MK-7. The major polar lipids of strain D3-2-R+10^T comprised phosphatidylethanolamine, one unidentified phospholipid and five unidentified lipids, while those of strain C2-6-M1^T included phosphatidylethanolamine, two unidentified phospholipids and seven unidentified lipids. The genome size of strains D3-2-R+10^T and C2-6-M1^T was 6.0 and 5.0 Mb, respectively, with the DNA G+C contents of 40.1 and 40.9 mol %. Based on the above descriptions, the six strains were identified as two novel species of the genus Algoriphagus, for which the names Algoriphagus aurantiacus sp. nov. and Algoriphagus persicinus sp. nov. were proposed, with the type strains, respectively.

Keywords: Algoriphagus; Xizang; genome; polyphasic taxonomy; salt lake.

Fig. 1.. The neighbour-joining tree reconstructed based on 16S rRNA gene sequences of strains D3-2-R+10^T, C2-6-M1^T, E1-3-M2, D2-2-M3, D2-2-M2 and D2-2-M1 and type species of the genus Algoriphagus. Bootstrap values higher than 70% are shown (percentages of 1,000 replications) on the branches. Filled circles indicate that the corresponding nodes were also present in the trees reconstructed using the maximum-likelihood and minimum-evolution algorithms. Bar represents 0.02 changes per nt position. Cytophaga hutchinsonii ATCC 33406^T was utilized as an outgroup.

Fig. 2.. The phylogenomic tree based on the genomic sequences of strains D3-2-R+10^T and C2-6-M1^T and type strains of the related species constructed using TYGS. Cytophaga hutchinsonii ATCC 33406^T was utilized as an outgroup.

Fig. 3.. Transmission electron micrograph of strains D3-2-R+10^T (a) and C2-6-M1^T (b) cultivated on MA plate at 25 °C for 72 h.

Fig. 4.. Absorption spectra of acetone/methanol cell extract from strains D3-2-R+10^T (a) and C2-6-M1^T (b) in the range of 300–900 nm. The absorbance peak at ~480 nm indicates the presence of carotenoids. The horizontal coordinate is wavelength, and the vertical coordinate is absorbance.