Vol.:(0123456789) 1 3 Extremophiles (2018) 22:955–963 https://doi.org/10.1007/s00792-018-1051-6 ORIGINAL PAPER Lipid A structural characterization from the LPS of the Siberian psychro‑tolerant Psychrobacter arcticus 273‑4 grown at low temperature Angela Casillo 1  · Marcello Ziaco 1  · Buko Lindner 2  · Ermenegilda Parrilli 1  · Dominik Schwudke 2  · Aurora Holgado 3,4  · Rudi Beyaert 3,4  · Rosa Lanzetta 1  · Maria Luisa Tutino 1  · Maria Michela Corsaro 1 Received: 20 March 2018 / Accepted: 13 August 2018 / Published online: 20 August 2018 © Springer Japan KK, part of Springer Nature 2018 Abstract Psychrobacter arcticus 273-4 is a Gram-negative bacterium isolated from a 20,000-to-30,000-year-old continuously fro- zen permafrost in the Kolyma region in Siberia. The survival strategies adopted to live at subzero temperatures include all the outer membrane molecules. A strategic involvement in the well-known enhancement of cellular membrane fluidity is attributable to the lipopolysaccharides (LPSs). These molecules covering about the 75% of cellular surface contribute to cold adaptation through structural modifications in their portions. In this work, we elucidated the exact structure of lipid A moiety obtained from the lipopolysaccharide of P. arcticus grown at 4 °C, to mimic the response to the real environment temperatures. The lipid A was obtained from the LPS by mild acid hydrolysis. The lipid A and its partially deacylated deriva- tives were exhaustively characterized by chemical analysis and by means of ESI Q-Orbitrap mass spectrometry. Moreover, biological assays indicated that P. arcticus 273-4 lipid A may behave as a weak TLR4 agonist. Keywords Psychrobacter arcticus 273-4 · Lipid A · Mass spectrometry · Psychrotolerant · Permafrost Introduction Much of life on Earth has evolved to colonize environments where the temperatures play a critical role in the selection and survival of a variety of organisms such as bacteria, archaea, yeasts, algae, insects, fishes and plants. These cold- adapted organisms are generally referred to as psychrophiles (Chattopadhyay et al. 2014). Cold adaptation mechanisms are the result of intrinsic genome-wide features that facilitate the growth at low tem- peratures. Comparative studies of cold-adapted microorgan- isms are beginning to reveal which adaptations are common to all the psychrophiles and which are specific to the par- ticular environment each psychrophile inhabits. Cold marine environments are distinctly different from cold terrestrial environments like permafrost: marine environments tend to have high thermal stability as well as stable solute con- centrations, while terrestrial environments do not. Conse- quently, genomic analysis of microorganisms isolated from marine environments likely reflects adaptations to stable low temperatures, while that from terrestrial environments may reveal unique mechanism of cold adaptation due to Communicated by S. Albers. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00792-018-1051-6) contains supplementary material, which is available to authorized users. * Angela Casillo angela.casillo@unina.it * Maria Michela Corsaro corsaro@unina.it 1 Department of Chemical Sciences, University of Naples “Federico II”, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126 Naples, Italy 2 Division of Bioanalytical Chemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 10, 23845 Borstel, Germany 3 Unit for Molecular Signal Transduction in Inflammation, VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium 4 Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium