Bioactivity of a Marine Diatom (Porosira glacialis [Grunow] Jorgensen 1905) Cultivated With and Without Factory Smoke CO2

Abstract

Using industrial emissions as a strategy for CO₂ sequestration through carbon capture and utilization (CCU) in cultivation of microalgae can potentially change cultivation factors such as pH, nutrient availability and presence of trace metals, which could alter the growth and metabolism of the microalgae. It is therefore important to investigate whether such changes in culturing conditions can lead to changes in the diatoms metabolism, such as production of unwanted toxic compounds or by reduction of the diatoms' natural ability to control the growth of competing microorganisms (e.g., by decreasing the production of antibacterial compounds). The cold-water marine diatom Porosira glacialis was cultivated in two, 6,000-L photobioreactors in an industrial setting; one culture had the direct addition of factory smoke, and to the other fresh air was added. The biomass was extracted and screened for toxicity in viability assays against human cells (cancer and normal lung fibroblasts) and development of sea urchin larvae (<i>Paracentrotus lividus</i>). Bioactivity was tested in two bacterial assays: growth inhibition assay and anti-biofilm assay. The results confirm earlier reports on the presence of toxic compounds against human cell lines and P. lividus larvae, but no elevated toxicity could be detected using factory smoke. Anti-biofilm activity was present in both cultures. This indicates that the natural toxic properties of the microalgae do not increase by adding factory smoke, and that we keep the beneficial ability of the microalga to suppress growth of bacteria. These are key elements in a successful, industrial-scale cultivation as the product is safe and at the same time the monocultures are not being contaminated by competing organisms.