Production of exopolysaccharides by Antarctic marine bacterial isolates

Nichols, C.A. Mancuso; Garon, Steven J.; Bowman, John P.; Raguénès, Gérard; Guézennec, Jean

doi:10.1111/j.1365-2672.2004.02216.x

Cited by 191 publications

(125 citation statements)

References 45 publications

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“…Biologically produced Fe-binding organic ligands are (i) related to alleviation of Fe stress [bacterially-produced siderophores (Rue and Bruland, 1995;Trick et al, 1995;Mawji et al, 2008;Velasquez et al, 2011), the toxin domoic acid produced by the diatom Nitzschia Maldonado et al, 2002)], (ii) retention of episodic iron input (Adly et al, 2015;Westrich et al, 2016), or (iii) ligands produced through biological recycling or basal biological activity such as hemes , ferritin (Castruita et al, 2008), polysaccharides (Ozturk et al, 2004;Hassler et al, 2011a), and EPS (Nichols et al, 2004;Hassler et al, 2011b;Norman et al, 2015). Interestingly, amongst most of these organic ligands, only EPS were reported to contribute to the pool of HS-like substances which is not surprising given that EPS and HS are polyfunctional macromolecules.…”

Section: Organic Ligands Distribution-sources Production and Loss Pmentioning

confidence: 99%

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

2017

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Iron-binding ligands are paramount to understanding iron biogeochemistry and its potential to set the productivity and the magnitude of the biological pump in >30% of the ocean. However, the nature of these ligands is largely uncharacterized and little is known about their sources, sensitivity to photochemistry and biological transformation, or scavenging behavior. Despite many uncertainties, there is no doubt that ligands are produced by a wide range of biotic and abiotic processes, and that the bulk ligand pool encompasses a diverse range of molecules. Despite widespread recognition of the likelihood of a continuum of ligand classes making up the bulk ligand pool, studies to date largely focused on the dominant ligand. Thus, most studies have overlooked the need to assess where these targeted molecules fit across the spectrum of ligands that comprise the bulk ligand pool. Here we summarize present knowledge to critically assess the source(s), function(s), production pathways, and loss mechanisms of three important iron-binding organic ligand groups in order to assess their distinctive characteristics and how they link with observed ligand distributions. We considered that ligands are contained in broad groupings of exopolymer substances (EPS), humic substances (HS), and siderophores; using literature data for speciation modeling suggested that this adequately described the iron speciation reported in the ocean. We hypothesize that a holistic viewpoint of the multi-faceted controls on ligands dynamics is essential to begin to understand why some ligands can be expected to dominate in particular oceanic regions, depth strata, or exhibit seasonality and/or lateral gradients. We advocate that the development of a regional classification will enhance our understanding of the changing composition of the bulk ligand pool across the global ocean and to help address to what extent seasonality influences the makeup of this pool. This classification, based on selected functional ligand classes, can act as a bridge to use future ligand datasets to fill in the gaps in the continuum.

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Section: Organic Ligands Distribution-sources Production and Loss Pmentioning

confidence: 99%

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

2017

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“…When grown in batch culture at temperatures near the predicted optimum for this strain, CAM025 produced exopolymer, and chemical analyses showed the purified EPS was composed primarily of neutral sugars (glucose, arabinose, fucose, and galactose), uronic acids (glucuronic acid), and sulfates (29). Sulfates carry a net negative charge at seawater pH (27); uronic acids also contain an acidic carboxyl group that is ionizable in these conditions.…”

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confidence: 99%

“…Studies of polar sea ice communities using cultivation-dependent and -independent techniques have shown that the "Gammaproteobacteria" are among the dominant taxonomic groupings (6,8,10,35). CAM025 exhibits growth in the temperature range of Ϫ2°C to 30°C, on media containing 1% to 12% (wt/vol) sea salts, and exhibits an enhanced mucoid morphology on marine media with added glucose (29).…”

mentioning

confidence: 99%

Effects of Incubation Temperature on Growth and Production of Exopolysaccharides by an Antarctic Sea Ice Bacterium Grown in Batch Culture

Nichols

Bowman

Guézennec

2005

Appl Environ Microbiol

107

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The sea ice microbial community plays a key role in the productivity of the Southern Ocean. Exopolysaccharide (EPS) is a major component of the exopolymer secreted by many marine bacteria to enhance survival and is abundant in sea ice brine channels, but little is known about its function there. This study investigated the effects of temperature on EPS production in batch culture by CAM025, a marine bacterium isolated from sea ice sampled from the Southern Ocean. Previous studies have shown that CAM025 is a member of the genus Pseudoalteromonas and therefore belongs to a group found to be abundant in sea ice by culture-dependent and -independent techniques. Batch cultures were grown at ؊2°C, 10°C, and 20°C, and cell number, optical density, pH, glucose concentration, and viscosity were monitored. The yield of EPS at ؊2°C and 10°C was 30 times higher than at 20°C, which is the optimum growth temperature for many psychrotolerant strains. EPS may have a cryoprotective role in brine channels of sea ice, where extremes of high salinity and low temperature impose pressures on microbial growth and survival. The EPS produced at ؊2°C and 10°C had a higher uronic acid content than that produced at 20°C. The availability of iron as a trace metal is of critical importance in the Southern Ocean, where it is known to limit primary production. EPS from strain CAM025 is polyanionic and may bind dissolved cations such at trace metals, and therefore the presence of bacterial EPS in the Antarctic marine environment may have important ecological implications.Sea ice is a major component of polar regions, covers millions of square kilometers even at the end of the polar summer (21), and provides a home to unique communities dominated by microorganisms (35). Sea ice begins to form as the temperature of seawater, with a salinity of 3.5%, drops to Ϫ1.8°C. As ice develops, a salting-out process occurs in which the marine salts excluded from the ice are concentrated in brine pockets. Brine channels develop as the ice rises above sea level. The dense brine drains through the layer of columnar congelation ice by gravity and flows to the underlying seawater (7). The sea ice produces highly variable microenvironments in terms of temperature, salinity, nutrient concentration, and light intensities within the columns, which may be as thick as 2 m. Salinity in sea ice brine can range from near that of freshwater to Ͼ15% at the ice-seawater interface (35). Temperatures can range from 0°C to Ϫ35°C. Sea ice is thus one of the coldest habitats on earth for marine life (22).In spite of these extremes, up to 20 to 30% of primary production in sea ice cycles through heterotrophic bacteria (24, 30). Complex microbial communities, dominated by diatoms in close association with bacteria (30), are concentrated in the lower 10 to 20 cm of sea ice, where nutrients are available from the seawater and light is available from the surface (35). Abundant bacterial populations have been found in thick annual pack ice, with psychrophilic bacteria being particularl...

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“…The excess charge for the highest replicate of WC is also high relative to published values for other organisms, and the values for SC are low (29)(30)(31)34); however, there is (18,22,29). Many bacterial species have been found to increase production of EPS with decreasing temperatures (25,36), although Kiliç and Dönmez (25) found that Micrococcus sp. increases production with increasing temperature.…”

Section: Discussionmentioning

confidence: 89%

Role of Extracellular Polymeric Substances in the Surface Chemical Reactivity of Hymenobacter aerophilus , a Psychrotolerant Bacterium

Baker

Lalonde

Konhauser

et al. 2010

Appl Environ Microbiol

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Bacterial surface layers, such as extracellular polymeric substances (EPS), are known to play an important role in metal sorption and biomineralization; however, there have been very few studies investigating how environmentally induced changes in EPS production affect the cell's surface chemistry and reactivity. Acidbase titrations, cadmium adsorption assays, and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the surface reactivities of Hymenobacter aerophilus cells with intact EPS (WC) or stripped of EPS (SC) and purified EPS alone. Linear programming modeling of titration data showed SC to possess functional groups corresponding to phosphoryl (pK a ϳ6.5), phosphoryl/amine (pK a ϳ7.9), and amine/hydroxyl (pK a ϳ9.9). EPS and WC both possess carboxyl groups (pK a ϳ5.1 to 5.8) in addition to phosphoryl and amine groups. FT-IR confirmed the presence of polysaccharides and protein in purified EPS that can account for the additional carboxyl groups. An increased ligand density was observed for WC relative to that for SC, leading to an increase in the amount of Cd adsorbed (0.53 to 1.73 mmol/liter per g [dry weight] and 0.53 to 0.59 mmol/liter per g [dry weight], respectively). Overall, the presence of EPS corresponds to an increase in the number and type of functional groups on the surface of H. aerophilus that is reflected by increased metal adsorption relative to that for EPS-free cells.Acid-base titrations are frequently used to characterize microbial cell surface reactivity, in particular, the ability of the cell to adsorb and desorb protons (19,21,47). This ability is conferred by the presence of proton-reactive surface functional groups that are also responsible for the surface adsorption of other cations, including dissolved metals. Thus, a microbe's ability to immobilize metals and influence metal transport is largely dependent on the nature of the reactive sites found at the cell-water interface, namely, their concentrations and chemical affinities (in terms of equilibrium surface stability constants) for cations such as protons and metals.Both Gram-negative and Gram-positive bacteria have been characterized extensively using acid-base titration to determine their reactivity with respect to geochemical processes (18,22,33). To date, most work has focused on mesophilic and strictly heterotrophic model organisms; however, some work has also been done with cyanobacteria (29, 44) and thermophiles (19,47). While proton sorption assays provide information on surface site densities and acidity constants, a more direct assessment of a microbe's ability to interact with aqueous metals is the metal adsorption assay, where a cell's ability to adsorb metal ions from solution is measured over a range of pH values. Metal adsorption assays have been used to characterize microbes from a wide variety of environments to determine their potential for bioremediation of heavy metal contamination (21, 26), their influence on geochemical cycling (5, 16), and their ability to serve as nucleation sites f...

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Production of exopolysaccharides by Antarctic marine bacterial isolates

Cited by 191 publications

References 45 publications

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

Toward a Regional Classification to Provide a More Inclusive Examination of the Ocean Biogeochemistry of Iron-Binding Ligands

Effects of Incubation Temperature on Growth and Production of Exopolysaccharides by an Antarctic Sea Ice Bacterium Grown in Batch Culture

Role of Extracellular Polymeric Substances in the Surface Chemical Reactivity of Hymenobacter aerophilus , a Psychrotolerant Bacterium

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