Effects of Natural Light Dilution on Microalgae Growth

Abstract

Abstract-In this study, the growth of the microalgae, Isochrysis sp. under different illumination levels of natural sunlight was evaluated. Isochrysis sp. was cultured in f/2 media with five variations of illumination exposures. Each experimental setup was cultured in a 1 L cylindrical column with aeration provided by an air pump. Results showed that the best growth was exhibited when microalgae culture was exposed to 73.6% of illumination exposure with a light-dark cycle of 43.88-28.36s per height of column. Said culture also gave the highest CO 2 fixation rate of 0.541 g CO 2 /day. This proved that optimum illumination exposure is one of the most important factors towards improving microalgae growth rate and enhancing its' carbon fixation ability.

Applications of microalga Chlorella vulgaris in aquaculture

“…; Harun et al . ). However, under heterotrophic growth conditions C. vulgaris can grow faster and generate higher cellular oil (Mitra et al .…”

Cultivation Of Microalgae (Chlorella vulgaris) For Biodiesel Production

“…Microalgae cells cultivated under limited light conditions assimilate carbon towards the synthesis of amino acids and other essential cell constituents, but under saturated light conditions, sugars and starch are formed via the pentose phosphate-reducing pathway, suggesting the dependence of the biomass composition with the light availability. In reality, cultures under continuous light are often used in research and the industry because this condition generally achieves the maximum growth rate recorded (10). However, some findings suggest the use of light/dark cycles instead of continuous light as it allows for either an increase in final concentration or a lowering of production costs.…”

“…For the latter, cell divisions are more frequent after the interruption of the illuminated phase. In addition, some enzymes of the pentose cycle of photosynthesis and CO2 fixation are inactive during illumination (10,11).…”

Microalgae: Cultivation and Application

“…This part of the solar spectrum is called "photosynthetic active radiation" (PARS) and accounts for 43 % of the solar radiation (Thimijan and Heins 1983). Microalgae cells cultivated under limited light conditions assimilate carbon towards the synthesis of amino acids and other essential cell constituents, but under saturated light conditions, sugars and starch are formed via the pentose phosphate-reducing pathway, suggesting the dependence of the biomass composition with the light availability (Harun et al 2014). Fluorescent tubes emitting either in the blue or the red light spectrum may be preferred as these are most active portion of the light spectrum for photosynthesis.…”

“…Further unlike light intensity, photoperiod (light/ dark cycle) plays a great role for microalgae culture. This is because cell division occurs under dark conditions for many unicellular photosynthetic cultures, while for others, cell division occurs both in the dark and the illuminated phase (Harun et al 2014). Although the photoperiod varies from organism to organism, for industrial applications relating the ratio between the cost of energy and the corresponding biomass production, 12-15 h of illumination is considered as the optimal period (Harun et al 2014).…”