Biofilm formation behaviour of marine filamentous cyanobacterial strains in controlled hydrodynamic conditions

Abstract

Summary Marine biofouling has severe economic impacts and cyanobacteria play a significant role as early surface colonizers. Despite this fact, cyanobacterial biofilm formation studies in controlled hydrodynamic conditions are scarce. In this work, computational fluid dynamics was used to determine the shear rate field on coupons that were placed inside the wells of agitated 12‐well microtiter plates. Biofilm formation by three different cyanobacterial strains was assessed at two different shear rates (4 and 40 s−1) which can be found in natural ecosystems and using different surfaces (glass and perspex). Biofilm formation was higher under low shear conditions, and differences obtained between surfaces were not always statistically significant. The hydrodynamic effect was more noticeable during the biofilm maturation phase rather than during initial cell adhesion and optical coherence tomography showed that different shear rates can affect biofilm architecture. This study is particularly relevant given the cosmopolitan distribution of these cyanobacterial strains and the biofouling potential of these organisms.

Experimental Assessment of the Performance of Two Marine Coatings to Curb Biofilm Formation of Microfoulers

“…and P. tunicata biofilms were developed on both surfaces for seven weeks under controlled hydrodynamic conditions that mimic those found in some marine settings. As the hydrodynamic forces bring a strong impact on marine biofilm development [23,32,38,39], the experiments were performed under specific shear forces that include the shear rate estimated for a ship in a harbor (50/s) [33] in order to increase the predictive value of the results.…”

“…Subsequently, 3 mL of each cell suspension was added to the wells, and the plates were incubated at 25 • C in an orbital shaker with 25 mm diameter (Agitorb 200ICP, Norconcessus, Ermesinde, Portugal) at 185 rpm under alternate light cycles of 14 h light (10-30 mol photons/m 2 /s)/10 h dark. According to previous computational fluid dynamic studies performed by the group [23,32], the selected shaking frequency of 185 rpm produces an average shear rate of 40/s and a maximum of 120/s at the plate bottom, including for instance the shear rate estimated for a ship in a harbor (50/s) [33]. Biofilm formation was monitored for seven weeks (49 days) and sampled every seven days.…”

Efficacy of A Poly(MeOEGMA) Brush on the Prevention of Escherichia coli Biofilm Formation and Susceptibility

“…In situ images of the biofilm structure were obtained with a Spectral Domain Optical Coherence Tomography (SD-OCT) system (Thorlabs GmbH, Dachau, Germany) with a central wavelength of 930 nm. The refractive index was set to 1.40, close to the refractive index of water (1.33), since water is the major component of biofilms [62]. Two-dimensional (2D) images were acquired after 24 h of biofilm formation and after the ampicillin treatment (the 32 h time point).…”

Unveiling the Antifouling Performance of Different Marine Surfaces and Their Effect on the Development and Structure of Cyanobacterial Biofilms

“…Then, 3 mL of cyanobacterial suspension at a final concentration of 1 × 10 8 cells•mL −1 was added to each well, and plates were incubated at 25 • C in an orbital shaker with a 25 mm diameter (Agitorb 200ICP, Norconcessus, Ermesinde, Portugal) at 185 rpm, under alternate light cycles of 14 h light (10-30 mol photons•m −2 •s −1 )/10 h dark. According to previous computational fluid dynamic studies using this type of incubator [14], a shaking frequency of 185 rpm corresponds to an average shear rate of 40 s −1 and a maximum of 120 s −1 , which encompasses the shear rate estimated for a ship in a harbor (50 s −1 ) [29].…”

“…In this study, the long-term performance of five surface materials-glass, perspex, polystyrene, epoxy-coated glass, and a silicone hydrogel coating-in inhibiting or delaying biofilm formation by microfoulers was evaluated. Glass, perspex, and polystyrene materials are commonly found on different marine facilities and equipment, including underwater windows of boats, aquaculture systems, flotation spheres, moored buoys, underwater cameras, measuring devices or sensors, pontoons, and floating docks [13,14]. In turn, polymer epoxy resin and silicone hydrogel are two commercial marine coatings; the first is used to coat the hulls of small recreation vessels (e.g., powerboats, yachts, and sailing boats) [15,16], while the second is frequently used to coat ship hulls, marine water inlet piping, and grids in power stations [17].…”