Influence of Growth Temperature on Lipid and Phosphate Contents of Surface Polysaccharides from the Antarctic Bacterium Pseudoalteromonas haloplanktis TAC 125

Abstract

The chemical structural variations induced by different growth temperatures in the lipooligosaccharide and exopolysaccharide components extracted from the Antarctic bacterium Pseudoalteromonas haloplanktis TAC 125 are described. The increase in phosphorylation with the increase in growth temperature seems to be general, because it happens not only for the lipooligosaccharide but also for the exopolysaccharide. Structural variations in the lipid components of lipid A also occur. In addition, free lipid A is found at both 25 and 4°C but not at 15°C, which is the optimal growth temperature, suggesting a incomplete biosynthesis of the lipooligosaccharide component under the first two temperature conditions. Lipopolysaccharides (LPSs) are amphiphilic molecules contained in the outer leaflet of the external membrane of gramnegative bacteria. They are anchored in the membrane by the lipid part (lipid A), which is covalently linked to an oligosaccharide fragment (core) that, in turn, is bonded to a polysaccharide part (O antigen, or O side chain). Due to their outward location, the LPSs are involved in mechanisms of interaction with the surroundings. Despite the fact that gram-negative bacteria colonize very different organisms and environments, LPSs show a common architectural structure (17). This suggests that the molecular structures of the LPS components can play an important role in host or environment specificity. In this context, the structures of LPSs of extremophilic bacteria evoke much interest owing to the extreme conditions under which they live (14). The cold adaptation of psychrophilic bacteria, which enables them to thrive in environments below 5°C, necessitates the acquisition of unique structural features for membrane components, so that membrane fluidity and effective transport of nutrients under cold conditions are guaranteed. The exopolysaccharides (EPSs) that many bacteria are able to produce may also be involved in interaction with the environment, in addition to having rheological properties of potential economical interest (6,19,21).Recently we have been interested in structural elucidation of both the saccharide backbones (5) and the lipid A moieties (4) of the LPS components of Pseudoalteromonas haloplanktis TAC 125, a cold-adapted bacterium isolated from Antarctic seawater (1) and grown at 15°C. In the first paper (5), Corsaro et al. showed that the LPS fraction consists of two lipooligosaccharides (LOSs); that is, it lacks the O chains. The major component possesses the following sugar backbone structure:The latter two units are both acylated at positions 2 and 3, with 3-hydroxydodecanoyl residues (3-OH-12:0) linked both as esters and as amides (4). The hydroxyl of the (3-OH-12:0) residue linked at position 3 of the nonreducing glucosamine is esterified by a dodecanoyl residue (12:0). Here we describe the variations that occur in the LOS structures when the bacterium is grown at two temperatures other than 15°C: one lower (4°C) and one higher (25°C). Since this bacterium is also able to produ...

Phylogenetic Analyses of the Genus Hymenobacter and Description of Siccationidurans gen. nov., and Parahymenobacter gen. nov

“…But several phenotypic markers are variable and dependent on environmental cues. For instance, the expression of characteristics that serve in genus description, such as cell morphology [39][40][41][42], enzymes [43,44], fatty acids [45,46] menaquinones [47][48][49], lipids [50][51][52][53] and peptidoglycan [54][55][56][57], depend on the growth conditions. Further, discrepancies in the above traits were well documented among species of several genera [58,59], and thus hamper in drawing congruence between phylogeny and expressed characteristics.…”

A Unique Capsular Polysaccharide Structure from the Psychrophilic Marine Bacterium Colwellia psychrerythraea 34H That Mimics Antifreeze (Glyco)proteins

“…[1][2][3] Because microorganisms are at thermal equilibrium with their environment, it is reasonable to assume that structural and functional components in psychrophiles (optimal growth at ≤ 15°C) have adapted, to some degree, to the requirements of a low temperature existence, 4 including the possible presence of ice crystals in their immediate surroundings. The reported mechanisms of bacterial adaptation to low temperature include the over-expression of cold-shock and heat-shock proteins, the presence of unsaturated and branched fatty acids that maintain membrane fluidity, 5 the different phosphorylation of membrane proteins and lipopolysaccharides, [6][7][8][9][10][11] and the production of cold-active enzymes, 12 antifreeze proteins and cryoprotectants. 13 The latter are chemical substances that generally include small molecules, such as glycine betaine, some amino acids, sugars (glucose, fructose) and sugar alcohols (mannitol, glycerol).…”

“…20 Despite their important roles in cryoprotection and environmental interactions, few exopolysaccharide structures from cold-adapted bacteria have been accurately elucidated. 7,19,21 In addition, an increased understanding of the structural characteristics of these polymers is a prerequisite to potential biotechnological exploitation of cold-adapted bacterial EPS. Colwellia psychrerythraea 34H is a Gram-negative bacterium belonging to the phylum γ-proteobacteria.…”

Large-Scale Transposon Mutagenesis ofPhotobacterium profundumSS9 Reveals New Genetic Loci Important for Growth at Low Temperature and High Pressure

“…Corsaro et al (25), have suggested that the psychrophile Pseudoalteromonas haloplanktis TAC125 is unable to complete the biosynthesis of lipooligosaccharide at a suboptimal temperature as the phosphorylation of both lipooligosaccharide and EPS decreases with temperature. In these molecules, phosphate groups bind to divalent cations, such as Ca 2ϩ and Mg 2ϩ , stabilizing the extracellular leaflet of the outer membrane (50,76) and modulating its permeability.…”

“…Workers have speculated about the involvement of capsular polysaccharide in adaptation to low temperature for some time (25,60,62). FL26 contains a disruption in the gene encoding the PBPRA0218 protein, a predicted O-antigen ligase for lipopolysaccharide (LPS) synthesis whose expression is reduced at low temperature (19,87).…”