The Effect of UV Light and CO₂ in the Production of Polyunsaturated Aldehydes in <i>Skeletonema costatum</i> (Bacillariophycea)

Abstract

Skeletonema costatum was submitted to two experiments using UV lights and CO2with the purpose of observing changes in the lipids profile and the synthesis of polyunsaturated aldehydes (PUA) after cell disruption. When cells receive CO2 supply, it was noticed that the production of PUA was significantly lower. The same was observed when the culture was treated with a dose of 45.9 kJ · m -2 of ultra-violet A/B ray. The premise to all experiments was the production of 2,4-heptadienal compared to the supply of EPA as substrate. As a result, the same synthesis rate was observed both when the CO2 treatment was applied and in the experiment control. On the other hand, the culture subjected to ultraviolet radiation showed a 68% greater demand with the utilization of the substrate. These observations suggested that EPA was consumed before cell disruption and was probably exuded to the surrounding environment as a sign of stress. Changes in cell morphology could be observed by the migration of the chloroplast nearby the cell wall, where PUA was produced, indicating a defense strategy.