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The Structure of the Lipid A from the Halophilic Bacterium Spiribacter salinus M19-40T.

ABSTRACT: The study of the adaptation mechanisms that allow microorganisms to live and proliferate in an extreme habitat is a growing research field. Directly exposed to the external environment, lipopolysaccharides (LPS) from Gram-negative bacteria are of great appeal as they can present particular structural features that may aid the understanding of the adaptation processes. Moreover, through being involved in modulating the mammalian immune system response in a structure-dependent fashion, the elucidation of the LPS structure can also be seen as a fundamental step from a biomedical point of view. In this paper, the lipid A structure of the LPS from Spiribacter salinus M19-40T, a halophilic gamma-proteobacteria, was characterized through chemical analyses and matrix-assisted laser desorption ionization (MALDI) mass spectrometry. This revealed a mixture of mono- and bisphosphorylated penta- to tri-acylated species with the uncommon 2 + 3 symmetry and bearing an unusual 3-oxotetradecaonic acid.

SUBMITTER: Barrau C

PROVIDER: S-EPMC5923411 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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The Structure of the Lipid A from the Halophilic Bacterium Spiribacter salinus M19-40<sup>T</sup>.

Barrau Clara C Di Lorenzo Flaviana F Menes Rodolfo Javier RJ Lanzetta Rosa R Molinaro Antonio A Silipo Alba A

Marine drugs 20180411 4

The study of the adaptation mechanisms that allow microorganisms to live and proliferate in an extreme habitat is a growing research field. Directly exposed to the external environment, lipopolysaccharides (LPS) from Gram-negative bacteria are of great appeal as they can present particular structural features that may aid the understanding of the adaptation processes. Moreover, through being involved in modulating the mammalian immune system response in a structure-dependent fashion, the elucida ...[more]

PMID: 29641496

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Project description:Members of the genus Spiribacter are found worldwide and are abundant in ecosystems possessing intermediate salinities between seawater and saturated salt concentrations. Spiribacter salinus M19-40 is the type species of this genus and its first cultivated representative. In the habitats of S. salinus M19-40, high salinity is a key determinant for growth and we therefore focused on the cellular adjustment strategy to this persistent environmental challenge. We coupled these experimental studies to the in silico mining of the genome sequence of this moderate halophile with respect to systems allowing this bacterium to control its potassium and sodium pools, and its ability to import and synthesize compatible solutes. S. salinus M19-40 produces enhanced levels of the compatible solute ectoine, both under optimal and growth-challenging salt concentrations, but the genes encoding the corresponding biosynthetic enzymes are not organized in a canonical ectABC operon. Instead, they are scrambled (ectAC; ectB) and are physically separated from each other on the S. salinus M19-40 genome. Genomes of many phylogenetically related bacteria also exhibit a non-canonical organization of the ect genes. S. salinus M19-40 also synthesizes trehalose, but this compatible solute seems to make only a minor contribution to the cytoplasmic solute pool under osmotic stress conditions. However, its cellular levels increase substantially in stationary phase cells grown under optimal salt concentrations. In silico genome mining revealed that S. salinus M19-40 possesses different types of uptake systems for compatible solutes. Among the set of compatible solutes tested in an osmostress protection growth assay, glycine betaine and arsenobetaine were the most effective. Transport studies with radiolabeled glycine betaine showed that S. salinus M19-40 increases the pool size of this osmolyte in a fashion that is sensitively tied to the prevalent salinity of the growth medium. It was amassed in salt-stressed cells in unmodified form and suppressed the synthesis of ectoine. In conclusion, the data presented here allow us to derive a genome-scale picture of the cellular adjustment strategy of a species that represents an environmentally abundant group of ecophysiologically important halophilic microorganisms.

Project description:Two Gram-positive, rod-shaped moderately halophilic bacterial strains, designated AD7-25(T) and AB-11, were isolated from Aiding and Manasi salt lakes in Xinjiang of China, respectively. The strains were found to be able to grow at NaCl concentrations of 0-21 % (w/v), with optimum growth occurring at 6-8 % (w/v) NaCl. The optimal temperature and pH for growth were determined to be 33-37 °C and pH 7.0-7.5. Cells of the strains are motile by means of polar flagella. Both strains can produce ellipsoidal spores. The major cellular fatty acids were identified as anteiso-C15:0, iso-C15:0, iso-C14:0, anteiso-C17:0 and iso-C16:0. The diamino acid in the peptidoglycan and the major quinone system were determined to be meso-diaminopimelic acid (meso-DAP) and MK-7, respectively. The DNA G+C contents of stains AD7-25(T) and AB-11 were 39.8 and 40.0 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that these two novel strains are closely related to the genus Oceanobacillus showing 90-99.5 % similarity with respect to type strains. These two novel strains were most closely related to Oceanobacillus oncorhynchi subsp. incaldanensis DSM 16557(T) (99.1 and 99.5 %), followed by O. oncorhynchi subsp. oncorhynchi JCM 12661(T) (99.1 and 99.4 %), Oceanobacillus neutriphilus CGMCC 1.7693(T) (97.0 and 97.5 %), Oceanobacillus sojae JCM 15792(T) (97.6 and 98.0 %) and Oceanobacillus locisalsi KCTC 13253(T) (96.5 and 96.9 %). The DNA-DNA hybridization data indicated that DNA relatedness between strains AD7-25(T) and AB-11 was 91.0 %, and the genomic homology of representative strain AD7-25(T) with O. oncorhynchi subsp. incaldanensis DSM 16557(T), O. oncorhynchi subsp. oncorhynchi JCM 12661(T), O. neutriphilus CGMCC 1.7693(T), O. sojae JCM 15792(T) and O. locisalsi KCTC 13253(T) were 41, 39, 20, 23 and 17 %, respectively. On the basis of phenotypic and phylogenetic distinctiveness, strains AD7-25(T) and AB-11 should be assigned to the genus Oceanobacillus as a new species, for which the name Oceanobacillus aidingensis sp. nov. was proposed. The type strain is AD7-25(T) (=CGMCC 1.9106 (T) = NBRC 105904(T)).

Dataset Information

The Structure of the Lipid A from the Halophilic Bacterium Spiribacter salinus M19-40T.

Publications

The Structure of the Lipid A from the Halophilic Bacterium Spiribacter salinus M19-40<sup>T</sup>.

Similar Datasets

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