Luteimonas salinilitoris sp. nov., isolated from the shore soil of saline lake in Tibet of China

Abstract

Five aerobic, Gram-stain-negative bacterial strains, designated as C3-2-a3^T, B3-2-R+30, C3-2-a4, C3-2-M3 and C3-2-M8, were isolated from the coastal soil of LungmuCo Lake in the Tibet Autonomous Region, PR China. Phylogenetic analyses based on 16S rRNA genes and genomes indicated that these isolates belonged to the genus Luteimonas and showed a high similarity to Luteimonas suaedae LNNU 24178^T (99.01%), Luteimonas endophytica RD2P54^T (98.80%) and Luteimonas salinisoli SJ-92^T (97.67%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain C3-2-a3^T and related reference strains Luteimonas suaedae LNNU 24178^T, Luteimonas endophytica RD2P54^T and Luteimonas salinisoli SJ-92^T were 91.89, 83.11 and 83.86% and 46.90, 26.90 and 28.20%, respectively. All values were below the thresholds for delineating species, supporting their classification as novel species of the genus Luteimonas. The genomic DNA G+C content of strains C3-2-a3^T was 68.39%. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and two unidentified phospholipids. The predominant respiratory quinone was ubiquinone-8 (Q-8), aligning with the characteristics of members of the genus Luteimonas. The major fatty acids (>10.0%) of strain C3-2-a3^T were identified as iso-C_{11 : 0}, iso-C_{15 : 0}, iso-C_{16 : 0} and iso-C_{17 : 1} ω9c. Based on the results of phenotypic, physiological, chemotaxonomic and genotypic characterizations, we propose that the isolates represent a novel species of genus Luteimonas, for which the name Luteimonas salinilitoris sp. nov is proposed. The type strain is C3-2-a3^T (=CGMCC 1.14507^T=KCTC 8642^T).

Keywords: Luteimonas salinilitorissp. nov.; Tibet; saline lake; soil.

Fig. 1.. Neighbour-joining phylogenetic tree based on 16S rRNA gene sequences. Bootstrap values >50% are shown at branch points based on 1000 resamplings. The filled circles indicate that the corresponding nodes were recovered in the maximum-likelihood and maximum-parsimony methods. Vulcaniibacterium tengchongense DSM 25623^T was used as an outgroup.

Fig. 2.. Phylogenomic tree based on the genome sequence of strains C3-2-a3^T and B3-2-R+30 on the TYGS. (http://tygs.dsmz.de/). The numbers above branches are GBDP pseudo-bootstrap support values >60% from 100 replications, with an average branch support of 91.1%.

Fig. 3.. Transmission electron micrograph of strain C3-2-a3^T cultivated on the MA plate at 25 ℃ for 48–72 h.

Fig. 4.. Two-dimensional TLC of the polar lipids of strains C3-2-a3^T (a) and B3-2-R+30 (b) stained with molybdophosphoric acid. DPG, diphosphatidylglycerol; PG, phosphatidylglycerol; PE，phosphatidylethanolamine; PL, unidentified phospholipid; L, unidentified lipid.

Fig. 5.. The GC-MS detection of the fatty acid composition summed feature 9 (iso-C_17 : 1 ω9c / C_16 : 0 10-methyl) of the of strains C3-2-a3^T, B3-2-R+30 and reference strain Luteimonas suaedae LNNU 24178^T. The iso-C_17 : 1 ω9c in strain C3-2-a3^T (a), strain B3-2-R+30 (b) and Luteimonas suaedae LNNU 24178^T (c) were shown as a peak with RT 19.990 min. The mass spectrum of iso-C_17 : 1 ω9c in strain C3-2-a3^T is shown in (d).