The Deep-Sea Polyextremophile Halobacteroides lacunaris TB21 Rough-Type LPS: Structure and Inhibitory Activity towards Toxic LPS.

Flaviana Di Lorenzo,Domenico Garozzo,Antonio Molinaro,Ida Paciello,Maria-Lina Bernardini,Violetta La Cono,Angelo Palmigiano,Alba Silipo,Mateusz Pallach,Michail M Yakimov

doi:10.3390/md15070201

Abstract

The structural characterization of the lipopolysaccharide (LPS) from extremophiles has important implications in several biomedical and therapeutic applications. The polyextremophile Gram-negative bacterium Halobacteroides lacunaris TB21, isolated from one of the most extreme habitats on our planet, the deep-sea hypersaline anoxic basin Thetis, represents a fascinating microorganism to investigate in terms of its LPS component. Here we report the elucidation of the full structure of the R-type LPS isolated from H. lacunaris TB21 that was attained through a multi-technique approach comprising chemical analyses, NMR spectroscopy, and Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry. Furthermore, cellular immunology studies were executed on the pure R-LPS revealing a very interesting effect on human innate immunity as an inhibitor of the toxic Escherichia coli LPS.

Highlights

In the last 30 years, the fascinating world of microorganisms able to survive and to proliferate at extreme conditions has attracted researchers in several multidisciplinary scientific fields
We report the structural characterization of the rough-type LPS (R-LPS) from H. lacunaris TB21, that turned out to express a unique structure that was established by a combination of organic chemistry, NMR spectroscopy, and mass spectrometry performed on the whole macromolecule and on its fully deacylated product
Purification, and Compositional Analyses of the R-LPS Isolated from H. lacunaris TB21

Summary

Introduction

In the last 30 years, the fascinating world of microorganisms able to survive and to proliferate at extreme conditions has attracted researchers in several multidisciplinary scientific fields. Spanning through the three domains of life, such microorganisms, known as extremophiles, were roughly distinguished on the basis of their optimal growth conditions [1,2] Within this frame, halophiles are organisms that require highly saline conditions for survival and proliferation. Halophiles are organisms that require highly saline conditions for survival and proliferation They inhabit various types of NaCl-saturated environments occurring throughout Earth’s biosphere, spanning a wide range of scales from solar salterns, inland salt-lakes, and deep-sea hypersaline anoxic brines (DHABs) [1,2]. The latter ecosystem is one of the harshest environments on planet Earth and is considered unconducive to the survival of common marine microorganisms. Highly heterogeneous and stratified microbial communities populate the brines and the interfaces of such basins [3]

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