Microbial Communities and Exopolysaccharides from Polynesian Mats

Rougeaux, Hélène; Guezennec, M.; Mao, Lydie; Payri, Claude; Deslandes, Éric; Guézennec, Jean

doi:10.1007/s101260000063

Cited by 24 publications

(23 citation statements)

References 20 publications

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“…All the models assume highly acidic exopolymers with each monomer carboxylated. In nature, carboxylate concentration per monomer is lower, with uronic acid monomers forming less than 40 wt % of the total polysaccharide monomers (e.g., Brown and Lester 1980;Rougeaux et al 2001;de Brouwer and Stal 2001). In nature, therefore, total EPS degradation should lead to more CO 2 released relative to Ca 2ϩ if compared to the model presented here.…”

Section: Modeling Of Factors Driving Caco 3 Precipitation In Satonda mentioning

confidence: 83%

Microbialite Formation in Seawater of Increased Alkalinity, Satonda Crater Lake, Indonesia

Arp

Reimer

Reitner

2003

Journal of Sedimentary Research

199

183

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The crater lake of the small volcanic island Satonda, Indonesia, is unique for its red-algal microbial reefs thriving in marinederived water of increased alkalinity. The lake is a potential analogue for ancient oceans sustaining microbialites under open-marine conditions. Current reef surfaces are dominated by living red algae covered by non-calcified biofilms with scattered cyanobacteria and diatoms. Minor CaCO 3 precipitates are restricted to the seasonally flooded reef tops, which develop biofilms up to 500 m thick dominated by the cyanobacteria Pleurocapsa, Calothrix, Phormidium, and Hyella. Microcrystalline aragonite patches form within the biofilm mucilage, and fibrous aragonite cements grow in exopolymer-poor spaces such as the inside of dead, lysed green algal cells, and reef framework voids. Cementation of lysed hadromerid sponge resting bodies results in the formation of ''Wetheredella-like'' structures. Hydrochemistry data and model calculations indicate that CO 2 degassing after seasonal mixis can shift the carbonate equilibrium to cause CaCO 3 precipitation. Increased concentrations of dissolved inorganic carbon limit the ability of autotrophic biofilm microorganisms to shift the carbonate equilibrium. Therefore, photosynthesis-induced cyanobacterial calcification does not occur. Instead, passive, diffusioncontrolled EPS-mediated permineralization of biofilm mucus at contact with the considerably supersaturated open lake water takes place. In contrast to extreme soda lakes, the release of Ca 2؉ from aerobic degradation of extracellular polymeric substances does not support CaCO 3 precipitation in Satonda because the simultaneously released CO 2 is insufficiently buffered.Subfossil reef parts comprise green algal tufts encrusted by microstromatolites with layers of fibrous aragonite and an amorphous, unidentified Mg-Si phase. The microstromatolites probably formed when Lake Satonda evolved from seawater to Ca 2؉ -depleted raised-alkalinity conditions because of sulfate reduction in bottom sediments and pronounced seasonality with deep mixing events and strong CO 2 degassing. The latter effect caused rapid growth of fibrous aragonite, while Mg-Si layers replaced the initially Mg-calcite-impregnated biofilms. This could be explained by dissolution of siliceous diatoms and sponge spicules at high pH, followed by Mg-calcite dissolution and Mg-silica precipitation at low pH due to heterotrophic activity within the entombed biofilms.

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Section: Modeling Of Factors Driving Caco 3 Precipitation In Satonda mentioning

confidence: 83%

Microbialite Formation in Seawater of Increased Alkalinity, Satonda Crater Lake, Indonesia

Arp

Reimer

Reitner

2003

Journal of Sedimentary Research

199

183

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“…The formation of phosphorite deposits in 'kopara' was studied by Jehl & Rougerie (1995) and Rougerie et al (1997). Exopolysaccharides were studied by Rougeaux et al (2001) and recently, in conjunction with the present investigation, by Richert et al (2005). The ultrastructure of accumulated exopolymers (mostly polysaccharides) was studied using Cryoscan scanning electron microscopy (De´farge et al, 1996), but only a few studies dealt with the microbial composition of 'kopara' mats using light microscopy (De´farge et al, 1994a, b;Mao Che et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Cyanobacterial populations that build ‘kopara’ microbial mats in Rangiroa, Tuamotu Archipelago, French Polynesia

Richert¹,

Golubić²,

Guédès³

et al. 2006

European Journal of Phycology

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Cyanobacterial populations, the primary producers and builders of 'kopara' microbial mats were studied in four selected ponds along the rim of the Rangiroa Atoll, French Polynesia using a polyphasic approach. Seven isolates were maintained in uni-cyanobacterial cultures, characterized morphotypically and phylogenetically by evaluating sequences of the 16S rRNA gene of about 620 base pairs in length. Cyanobacteria in natural populations were analyzed microscopically, characterized morphotypically, and compared with cultured strains. Three of the isolates were identified in the field samples: Lyngbya aestuarii, Johannesbaptistia pellucida and Chroococcus submarinus were present in the mats only as minor components, whereas the species of Schizothrix that dominated the mat community could not be cultured. The sequence of Johannesbaptistia pellucida is published for the first time. The phylogenetic and taxonomic relations are discussed on the basis of a reconstructed phylogenetic tree in relation to morphotypic characters. Sequences of Kopara isolates plot separately from those cultured from the lagoon of the neighbouring atoll Tikehau, indicating a narrow niche differentiation of benthic cyanobacterial taxa. The results support the application of a polyphasic approach to characterization, ecology and diversity of cyanobacteria.

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“…1) with multispectral remote sensing data (Andréfouët et al in press). The image-based inventory and subsequent in situ survey enabled the reconnaissance of a few highly stratified kopara mats that later confirmed their biotechnological potential (Rougeaux et al 2001). Preliminary results obtained from two Rangiroa kopara mats show that their upper layers are a source of promising exopolysaccharides (EPSs) for biotechnological applications.…”

mentioning

confidence: 88%

“…Kopara mats persist under contrasting environmental situations, from submergence in shallow pools to completely dry, presenting desiccated polygonal patterns. In environments protected from wave flushing and from human and animal perturbations, kopara are generally vertically laminated with oxygenic phototrophic prokaryotes (cyanobacteria) in the upper layers and anoxygenic phototrophic and anaerobic heterotrophic bacteria in the deeper horizons (Défarge et al 1994b;Rougeaux et al 2001). The complex vertical organization of the microorganisms results from gradients of light, oxygen, and sulfide.…”

mentioning

confidence: 99%

Airborne hyperspectral detection of microbial mat pigmentation in Rangiroa atoll (French Polynesia)

Andréfouët

Payri

Hochberg

et al. 2003

Limnology & Oceanography

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The pigmentation of a cyanobacterial mat located in Rangiroa atoll (French Polynesia) was characterized using low-altitude (500 m) Compact Airborne Spectrometer Imager hyperspectral measurements. Peaks in second and fourth derivatives of the reflective absorptance can be explained by chlorophyll and carotenoid pigments, which were independently identified by high-pressure liquid chromatography. Phycobilin pigments were also detected from airborne measurements. The study confirms the extensibility of derivative spectroscopy from in vivo to highresolution remote sensing measurements for biology and geochemistry investigations in marine communities.

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Microbial Communities and Exopolysaccharides from Polynesian Mats

Cited by 24 publications

References 20 publications

Microbialite Formation in Seawater of Increased Alkalinity, Satonda Crater Lake, Indonesia

Microbialite Formation in Seawater of Increased Alkalinity, Satonda Crater Lake, Indonesia

Cyanobacterial populations that build ‘kopara’ microbial mats in Rangiroa, Tuamotu Archipelago, French Polynesia

Airborne hyperspectral detection of microbial mat pigmentation in Rangiroa atoll (French Polynesia)

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