Long‐term biofouling formation mediated by extracellular proteins in Nannochloropsis gaditana microalga cultures at different medium N/P ratios

Abstract

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).

CFD-based prediction of initial microalgal adhesion to solid surfaces using force balances

“…Culture gowth was monitored daily, measuring the relative cell concentration by absorbance in a plate reader (SynergyMx, BioTek Instruments Inc., USA) at a wavelength of 540 nm (Abs540). The relationship between biomass concentration and absorbance was obtained from Soriano-Jerez et al (2020). The photosynthetic health status of the culture was monitored with the maximum photochemical performance of photosystem II (Fv/Fm) in a pulsed light fluorimeter (PAM-2500 chlorophyll fluorometer, Heinz Walz GmbH, Effeltrich, Germany) (López-Rosales et al 2014).…”