Production and enzymatic hydrolysis of carbohydrates in intertidal sediment

Thornton, Daniel C. O.; Kopac, Sarah M.; Long, Richard A.

doi:10.3354/ame01403

Cited by 9 publications

(5 citation statements)

References 69 publications

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“…e -Enzymes are also known to be contained within extracellular vesicles, localized within the expolymer matrix ( Mashburn and Whiteley, 2005 ; Mashburn-Warren et al, 2008 ; Elhanawy et al, 2014 ), and e-DNA nucleases were found in Vibrio cholerae biofilms ( Seper et al, 2011 ). Indeed, elevated microbial activities, such as enzymatic activities, have been reported in marine snow particles at higher-levels than those in surrounding sea water ( Smith et al, 1992 ; Ploug et al, 1999 ; Grossart et al, 2003 ; Jatt et al, 2015 ), thus suggesting that marine snow are hotspots for remineralization of organic and inorganic materials ( Azam and Long, 2001 ; Thornton et al, 2010 ).…”

Section: Localization Of Microbial Extracellular Processesmentioning

confidence: 99%

Microbial Extracellular Polymeric Substances (EPSs) in Ocean Systems

2017

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Microbial cells (i.e., bacteria, archaea, microeukaryotes) in oceans secrete a diverse array of large molecules, collectively called extracellular polymeric substances (EPSs) or simply exopolymers. These secretions facilitate attachment to surfaces that lead to the formation of structured ‘biofilm’ communities. In open-water environments, they also lead to formation of organic colloids, and larger aggregations of cells, called ‘marine snow.’ Secretion of EPS is now recognized as a fundamental microbial adaptation, occurring under many environmental conditions, and one that influences many ocean processes. This relatively recent realization has revolutionized our understanding of microbial impacts on ocean systems. EPS occur in a range of molecular sizes, conformations and physical/chemical properties, and polysaccharides, proteins, lipids, and even nucleic acids are actively secreted components. Interestingly, however, the physical ultrastructure of how individual EPS interact with each other is poorly understood. Together, the EPS matrix molecules form a three-dimensional architecture from which cells may localize extracellular activities and conduct cooperative/antagonistic interactions that cannot be accomplished efficiently by free-living cells. EPS alter optical signatures of sediments and seawater, and are involved in biogeomineral precipitation and the construction of microbial macrostructures, and horizontal-transfers of genetic information. In the water-column, they contribute to the formation of marine snow, transparent exopolymer particles (TEPs), sea-surface microlayer biofilm, and marine oil snow. Excessive production of EPS occurs during later-stages of phytoplankton blooms as an excess metabolic by product and releases a carbon pool that transitions among dissolved-, colloidal-, and gel-states. Some EPS are highly labile carbon forms, while other forms appear quite refractory to degradation. Emerging studies suggest that EPS contribute to efficient trophic-transfer of environmental contaminants, and may provide a protective refugia for pathogenic cells within marine systems; one that enhances their survival/persistence. Finally, these secretions are prominent in ‘extreme’ environments ranging from sea-ice communities to hypersaline systems to the high-temperatures/pressures of hydrothermal-vent systems. This overview summarizes some of the roles of exopolymer in oceans.

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Section: Localization Of Microbial Extracellular Processesmentioning

confidence: 99%

Microbial Extracellular Polymeric Substances (EPSs) in Ocean Systems

2017

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“…Secondary nutrient limitation of P or Si was avoided through additions of both elements at 0 days for P and 2.5 days for Si during incubation. It is more likely that the microbial community responded to pulses of increased nutrients through increased production of extracellular compounds (MPB: carbohydrates; bacteria: enzymes) rather than increasing their biomass (Thornton et al, 2010). This may be a strategy to optimally utilize intermittently available nutrient resources, given that increased cell numbers (biomass) within a biofilm community may otherwise increase competition among cells (Decho, 2000;Drescher et al, 2014).…”

Section: Retention Of Carbon Within Microphytobenthos Biomassmentioning

confidence: 99%

Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a <sup>13</sup>C pulse-chase experiment

2018

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Abstract. Shallow coastal waters in many regions are subject to nutrient enrichment. Microphytobenthos (MPB) can account for much of the carbon (C) fixation in these environments, depending on the depth of the water column, but the effect of enhanced nutrient availability on the processing and fate of MPB-derived C (MPB-C) is relatively unknown. In this study, MPB was labeled (stable isotope enrichment) in situ using 13C-sodium bicarbonate. The processing and fate of the newly fixed MPB-C was then traced using ex situ incubations over 3.5 days under different concentrations of nutrients (NH4+ and PO43-: ambient, 2× ambient, 5× ambient, and 10× ambient). After 3.5 days, sediments incubated with increased nutrient concentrations (amended treatments) had increased loss of 13C from sediment organic matter (OM) as a portion of initial uptake (95 % remaining in ambient vs. 79–93 % for amended treatments) and less 13C in MPB (52 % ambient, 26–49 % amended), most likely reflecting increased turnover of MPB-derived C supporting increased production of extracellular enzymes and storage products. Loss of MPB-derived C to the water column via dissolved organic C (DOC) was minimal regardless of treatment (0.4–0.6 %). Loss due to respiration was more substantial, with effluxes of dissolved inorganic C (DIC) increasing with additional nutrient availability (4 % ambient, 6.6–19.8 % amended). These shifts resulted in a decreased turnover time for algal C (419 days ambient, 134–199 days amended). This suggests that nutrient enrichment of estuaries may ultimately lead to decreased retention of carbon within MPB-dominated sediments.

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“…However in the case of nutrient deficiency, MPB is in competition with bacteria and the growth of bacteria remains limited (Waksman and Butler, 1937). In spite of strong levels of organic matter in muddy sediments, a correlation between algal production and exoenzymatic activities of bacteria was highlighted during field studies (Hanlon et al, 2006;van Duyl et al, 1999) and during experimentation on diluted sediment (Goto et al, 2001;Haynes et al, 2007;Thornton et al, 2010). Concerning the structure of the bacterial community, some studies suggest that algal-bacterial coupling in estuarine sediments is likely to involve particular taxa rather than a response from the entire bacterial community (Amin et al, 2012;Bellinger et al, 2009;Hanlon et al, 2006;Haynes et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Bacterial dynamics in a microphytobenthic biofilm: A tidal mesocosm approach

Agogué

Mallet

Orvain

et al. 2014

Journal of Sea Research

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In intertidal mudflats, during low tide exposure, microphytobenthos (MPB) migrate vertically through the surface sediment and form, with the heterotrophic bacteria, a transient biofilm. Inside this biofilm, multiple interactions exist between MPB and bacteria. These micro-organisms secrete a wide range of extracellular polymeric substances (EPS), which are major components of the biofilm matrix. In this study, we used a tidal mesocosm experiment in order to decipher the interactions of the MPB-EPS-bacteria complex within the biofilm. We tried to determine if the EPS could control bacterial activities and/or production and/or richness according to the age of the biofilm and to the immersion/emersion period. The dynamics of biomasses of MPB and prokaryotes, the bacterial production, the hydrolysis of predominating organic constituents in the dissolved organic carbon (DOC) pool (i.e., carbohydrates and polypeptides), and the bacterial structure were studied in relation to the different EPS fractions (carbohydrates and proteins: colloidal and bound) dynamics during 8 days. Our experiment had emphasized the influence of the environmental conditions (light, immersion/emersion) on the interactions within the biofilm and also on the effects on biofilm ageing. Bacterial production was always inhibited by the bound EPS-carbohydrate, especially during low tide. Our results suggest that the concentration and composition of EPS had a major role in the bacterial/MPB interactions: these interactions can be either positive or negative in order to regulate the productive phases of MPB and bacteria.

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Production and enzymatic hydrolysis of carbohydrates in intertidal sediment

Cited by 9 publications

References 69 publications

Microbial Extracellular Polymeric Substances (EPSs) in Ocean Systems

Microbial Extracellular Polymeric Substances (EPSs) in Ocean Systems

Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a <sup>13</sup>C pulse-chase experiment

Bacterial dynamics in a microphytobenthic biofilm: A tidal mesocosm approach

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Production and enzymatic hydrolysis of carbohydrates in intertidal sediment

Cited by 9 publications

References 69 publications

Microbial Extracellular Polymeric Substances (EPSs) in Ocean Systems

Microbial Extracellular Polymeric Substances (EPSs) in Ocean Systems

Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a &lt;sup&gt;13&lt;/sup&gt;C pulse-chase experiment

Bacterial dynamics in a microphytobenthic biofilm: A tidal mesocosm approach

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Short-term fate of intertidal microphytobenthos carbon under enhanced nutrient availability: a <sup>13</sup>C pulse-chase experiment