06 Apr 2023
 | 06 Apr 2023
Status: a revised version of this preprint is currently under review for the journal BG.

Properties of exopolymeric substances (EPS) produced during cyanobacterial growth: potential role in whiting events

Marlisa Martinho de Brito, Irina Bundeleva, Frédéric Marin, Emmanuelle Vennin, Annick Wilmotte, Laurent Plasseraud, and Pieter T. Visscher

Abstract. Extracellular polymeric substances (EPS) are an important organic carbon reservoir in many pelagic and benthic environments. The production of EPS is intimately associated with the growth of phyto- and picoplankton. EPS plays a critical role in carbonate precipitation through the binding of cations and by acting as a nucleation site for minerals. Large-scale episodes of fine-grained calcium carbonate precipitation in the water column (whiting events) have been linked to cyanobacterial blooms, including of Synechococcus spp.,. The mechanisms that trigger these precipitation events are still debated. We pose that the cyanobacterial EPS, produced during exponential and stationary growth phases plays a critical role in the formation of whitings. The aim of this study was to investigate the production of EPS during a two-month cyanobacterial growth, mimicking a bloom. We further evaluated the potential role of EPS in carbonate precipitation. The production and properties of EPS produced at different Synechococcus spp. growth stages were investigated and carbonate mineral formation within these EPS matrices was determined in forced precipitation experiments. EPS produced during the early and late stationary phase contained a larger amount of negatively charged groups than present in EPS produced during the exponential phase. Consequently, a higher Ca2+ binding affinity of the stationary phase-EPS led to the formation of a larger amount of smaller carbonate minerals (<50 µm) compared to crystals formed in exponential phase-EPS, which were less and larger (> 50 µm). These findings were used to establish a conceptual model for picoplankton bloom-mediated CaCO3 precipitation that can explain the role of EPS in whitings (see graphical abstract).

Marlisa Martinho de Brito et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2023-51', Anonymous Referee #1, 25 Apr 2023
    • AC1: 'Reply on RC1', Marlisa Martinho De Brito, 30 May 2023
  • RC2: 'Comment on bg-2023-51', Sven Tobias-Hunefeld, 26 Apr 2023
    • AC2: 'Reply on RC2, Dr. Sven Tobias-Hunefeld', Marlisa Martinho De Brito, 30 May 2023
      • AC3: 'Reply on AC2, Dr. Sven Tobias-Hunefeld', Marlisa Martinho De Brito, 30 May 2023
    • AC4: 'Reply on RC2, Dr. Sven Tobias-Hunefeld', Marlisa Martinho De Brito, 30 May 2023

Marlisa Martinho de Brito et al.

Marlisa Martinho de Brito et al.


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Short summary
Cyanobacterial blooms are associated with whitings events - natural occurrences of fine-grained carbonate precipitation in the water column. The role of organic matter (OM) produced by cyanobacteria in these events was overlooked in previous research. Our laboratory experiments showed that OM has implications on the size and quantity of CaCO3 minerals. We propose a model of OM-associated CaCO3 precipitation during picoplankton blooms, which may have been neglected in modern and ancient events.