Testing the yield of a pilot‐scale bubble column photobioreactor for cultivation of the microalgaRhodomonas salinaas feed for intensive calanoid copepod cultures

Abstract

A dual column photobioreactor (PBR) (2 × 47 L) with mixed CO 2 /air bubbling was tested for cultivation of the microalga Rhodomonas salina as food for live feed copepods. In the continuous growth phase, the cell density was relatively stable at 2.40 ± 0.13 × 10 6 cells/ml at an average dilution rate of 0.46 ± 0.02 per day throughout the 30-day experiment. The produced algae had a high content of both total fatty acids (TFA) and free amino acids (FAA). Especially, the harvested algae contained a high proportion of poly-unsaturated fatty acids that made up 80% of the TFA and of essential amino acids (35% of all FAA), implicating desirable components as feed for copepods. The current PBR was sufficient to feed a culture of the calanoid copepod Acartia tonsa at a density of 2,500 adult/L in ca. 500 L culture with a daily yield of approximately 17 × 10 6 eggs. To be able to sustain the integrated copepods production, the suggested volume of the algae cultures should be ca. 20% of the copepod culture volume. K E Y W O R D Samino acids, dilution rate, fatty acids, growth rate, live feed, upscaling

The Effect of Nitrogen Starvation on Biomass Yield and Biochemical Constituents of Rhodomonas sp.

“…in this study were palmitic (C16:0), linoleic (C18:2), linolenic (C18:3), and stearidonic (C18:4) acid. These FA's are in line with the literature results for Rhodomonas species (van Houcke et al, 2017;Vu et al, 2019;Coutinho et al, 2020). However, differ from lipid profiles of other microalgae that are used in aquaculture, for example, Tisochrysis lutea, Chaetoceros neogracile, Skeletonema marinoı, Pavlova lutheri, Nitzschia sp., Thalassiosira sp.…”

Industrial microalgae production for aquaculture hatcheries

“…A maximum average hourly biomass productivity of 12 ± 3 mg l -1 hlight -1 was achieved. Literature described 5.4 mg l -1 hlight -1 for Vu et al and 0.8 -3.3 mg l -1 hlight -1 for Thoisen et al[59,68]. The volumetric biomass productivity expressed per hour of light shows that the actual biomass productivity obtained under sunlight conditions in our results is 2-5x higher than those reported in literature.…”

“…In a light limited situation, the cultivation temperature and the available light will determine the maximum growth rate. [67,68] and one study reports a lab scale system with continuous conditions [69]. Thoisen et al [67] describe a tubular photobioreactor setup (200L) operating continuously with fixed biomass concentrations between 0.5-2.0*10 6 cells ml -1 at growth rates of 0.28 and 0.…”

“…We recently published advancements in continuous cultivation of the strains in lab-scale photobioreactors [96]. As a next step we would like to demonstrate production at larger [67,68]. In both aforementioned studies artificial light conditions were used for consistent growth conditions.…”

“…52 d -1producing approximately 0.02-0.08 g l -1 d -1 . Vu et al[68] describe a bubble-column (84L)for Rhodomonas production with a concentration of 2.4*10 6 cells ml -1 with a dilution rate of0.46 d -1 achieving an average production rate of about 0.11 g l -1 d -1 under continuous operation. Studies with other algal species grown under continuous operation at pilot scale outdoors show much higher biomass production rates.…”