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Parker, Dorothy L.; Mihalick, Jennifer E.; Plude, J.L.; Plude, Michelle J.; Clark, Thomas P.; Egan, Lynn; Flom, Joshua J.; Rai, L.C.; Kumar, Harish

doi:10.1023/a:1008195312218

Cited by 51 publications

(5 citation statements)

References 12 publications

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“…While cations also bind cooperatively in the toxic strain M. aeruginosa PCC 7806, this specie is less likely to bloom in nature as its salt thresholds are 3 to 6 times higher than in the nontoxic strain. Although both synergistic and competitive associations between cyanobacterial EPS and metals have been reported previously [36,46,47], the underlying mechanisms remain poorly understood and more work is needed to elucidate these binding processes. In this respect, similar experiments performed with cyanobacterial mutants of Synechocystis sp.…”

Section: Discussionmentioning

confidence: 99%

Irreversible Collective Migration of Cyanobacteria in Eutrophic Conditions

2015

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In response to natural or anthropocentric pollutions coupled to global climate changes, microorganisms from aquatic environments can suddenly accumulate on water surface. These dense suspensions, known as blooms, are harmful to ecosystems and signicantly degrade the quality of water resources. In order to determine the physico-chemical parameters involved in their formation and quantitatively predict their appearance, we successfully reproduced irreversible cyanobacterial blooms in vitro. By combining chemical, biochemical and hydrodynamic evidences, we identify a mechanism, unrelated to the presence of internal gas vesicles, allowing the sudden collective upward migration in test tubes of several cyanobacterial strains (Microcystis aeruginosa PCC 7005, Microcystis aeruginosa PCC 7806 and Synechocystis sp. PCC 6803). The final state consists in a foamy layer of biomass at the air-liquid interface, in which micro-organisms remain alive for weeks, the medium lying below being almost completely depleted of cyanobacteria. These "laboratory blooms" start with the aggregation of cells at high ionic force in cyanobacterial strains that produce anionic extracellular polymeric substances (EPS). Under appropriate conditions of nutrients and light intensity, the high photosynthetic activity within cell clusters leads the dissolved oxygen (DO) to supersaturate and to nucleate into bubbles. Trapped within the EPS, these bubbles grow until their buoyancy pulls the biomass towards the free surface. By investigating a wide range of spatially homogeneous environmental conditions (illumination, salinity, cell and nutrient concentration) we identify species-dependent thresholds and timescales for bloom formation. We conclude on the relevance of such results for cyanobacterial bloom formation in the environment and we propose an ecient method for biomass harvesting in bioreactors.

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Section: Discussionmentioning

confidence: 99%

Irreversible Collective Migration of Cyanobacteria in Eutrophic Conditions

2015

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“…As a consequence, pollutants become available for cellular biodegradation. In addition, the emergence of sorption properties in CB, which contribute to the extracellular detoxification of pollutants, is exudation of mucus [10]. In [11], it was found that hydrocarbon-oxidizing bacteria live in the sheaths of CB capable of growing in the presence of crude oil and decomposing its components.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the possibility of biological modification and regeneration of plant-based sorption materials

Zemtsova,

Gornostaeva

2024

E3S Web of Conf.

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“…While similar experiments on indoor samples may still be qualitative, it would be interesting to test the mechanisms identified in this study using natural samples. Although the aggregation and binding of cyanobacteria EPS to form algal blooms have been reported ( Parker et al., 2000 ; Micheletti et al., 2008 ), the underlying mechanisms were still poorly understood, and more work is needed to elucidate these binding processes. In this regard, similar experiments on algae with differences in EPS production can provide valuable data for further understanding the cell aggregation process.…”

Section: Discussionmentioning

confidence: 99%

Rapid flotation of Microcystis wesenbergii mediated by high light exposure: implications for surface scum formation and cyanobacterial species succession

Yang,

Pan,

et al. 2024

Front. Plant Sci.

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Increasing occurrences of Microcystis surface scum have been observed in the context of global climate change and the increase in anthropogenic pollution, causing deteriorating water quality in aquatic ecosystems. Previous studies on scum formation mainly focus on the buoyancy-driven floating process of larger Microcystis colonies, neglecting other potential mechanisms. To study the non-buoyancy-driven rapid flotation of Microcystis, we here investigate the floating processes of two strains of single-cell species (Microcystis aeruginosa and Microcystis wesenbergii), which are typically buoyant, under light conditions (150 μmol photons s−1 m−2). Our results showed that M. wesenbergii exhibited fast upward migration and formed surface scum within 4 hours, while M. aeruginosa did not form visible scum throughout the experiments. To further explore the underlying mechanism of these processes, we compared the dissolved oxygen (DO), extracellular polymeric substance (EPS) content, and colony size of Microcystis in different treatments. We found supersaturated DO and the formation of micro-bubbles (50–200 µm in diameter) in M. wesenbergii treatments. M. aeruginosa produces bubbles in small quantities and small sizes. Additionally, M. wesenbergii produced more EPS and tended to aggregate into larger colonies. M. wesenbergii had much more derived-soluble extracellular proteins and polysaccharides compared to M. aeruginosa. At the same time, M. wesenbergii contains abundant functional groups, which was beneficial to the formation of agglomerates. The surface scum observed in M. wesenbergii is likely due to micro-bubbles attaching to the surface of cell aggregates or becoming trapped within the colony. Our study reveals a species-specific mechanism for the rapid floatation of Microcystis, providing novel insights into surface scum formation as well as succession of cyanobacterial species.

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Cited by 51 publications

References 12 publications

Irreversible Collective Migration of Cyanobacteria in Eutrophic Conditions

Irreversible Collective Migration of Cyanobacteria in Eutrophic Conditions

Investigation of the possibility of biological modification and regeneration of plant-based sorption materials

Rapid flotation of Microcystis wesenbergii mediated by high light exposure: implications for surface scum formation and cyanobacterial species succession

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