Biofouling represents an important limitation in photobioreactor cultures. The biofouling propensity of different materials (polystyrene, borosilicate glass, polymethyl methacrylate, and polyethylene terephthalate glycol‐modified) and coatings (two spray‐applied and nanoparticle‐based superhydrophobic coatings and a hydrogel‐based fouling release coating) was evaluated by means of a short‐term protein test, using bovine serum albumin (BSA) as a model protein, and by the long‐term culture of the marine microalga Nannochloropsis gaditana under practical conditions. The results from both methods were similar, confirming that the BSA test predicts microalgal biofouling on surfaces exposed to microalgae cultures whose cells secrete macromolecules, such as proteins, with a high capacity for forming a conditioning film before cell adhesion. The hydrogel‐based coating showed significantly reduced BSA and N. gaditana adhesion, whereas the other surfaces failed to control biofouling. Microalgal biofouling was associated with an increased concentration of sticky extracellular proteins at low N/P ratios (below 15).

Nannochloropsis gaditana B-3 species (Instituto de Ciencias Marinas de Andalucía (CSIC, Cádiz, Spain)) was cultured in a 13-L flat panel photobioreactor (Figure B) for 71 days (Figure B). Cultures were illuminated in 12h:12h light-dark cycles at 135 µE•s -1 •m -2 (irradiance measured on the external surface of the PBR wall). Light was provided by a

An improved method that allows the robust characterization of surfaces is necessary to accurately predict the biofouling formation on construction materials of photobioreactors (PBR). Exopolymeric substances (EPS), such as proteins and polysaccharides, have been demonstrated to present a similar behavior to cells in terms of surface adhesion. In this work, these EPS were used to optimize parameters, such as EPS concentration or adsorption time, to evaluate accurately the adsorption capacity of surfaces and, with it, predict the biofouling formation in contact with microalgae cultures. Once the method was optimized, the characterization of seven commercial polymeric surfaces was submitted to different abrasive particles sizes, which modified the roughness of the samples, as well as protein and polysaccharide lawns, which were prepared and carried out in order to evaluate the characteristics of these substances. The characterization consisted of the determination of surface free energy, water adhesion tension, and critical tension determined from the measurement of the contact angle, roughness, surface zeta potential, and the EPS adhesion capacity of each material. This will be useful to understand the behavior of the surface in the function of its characteristics and the interaction with the solutions of EPS, concluding that the hydrophobic and smooth surfaces present good anti-biofouling characteristics.

Biofouling represents an important limitation in photobioreactor cultures. The biofouling propensity of different materials (polystyrene, borosilicate glass, polymethyl methacrylate and polyethylene terephthalate glycol-modified) and coatings (two spray-applied and nanoparticle-based superhydrophobic coatings and a hydrogel-based fouling release coating) was evaluated by means of a short-term protein test, using bovine serum albumin (BSA) as a model protein, and by the long-term culture of the marine microalga Nannochloropsis gaditana under practical conditions. The results from both methods were similar, confirming that the BSA test predicts microalgal biofouling on surfaces exposed to microalgae cultures; these secrete macromolecules, such as proteins, that have a high capacity for forming a conditioning film prior to cell adhesion. The hydrogel-based coating showed significantly reduced BSA and N. gaditana adhesion, whereas the other surfaces failed to control biofouling. Microalgal biofouling was associated with an increased concentration of sticky extracellular proteins at low N/P ratios (below 15).

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