Effect of photoperiod (PP) and photosynthetic photon flux intensity (PPFI) on nutrients consumption, growth and lipid profile of unusual microalga <em>Picochlorum maculatum</em> (PSDK01) in shrimp culture effluent

Abstract

Microalgae have been known for broad spectrum of ecological and industrial applications. However, continuous mass culturing of microalgae is still a challenging task. In this context, studies on optimization of culturing conditions like photoperiod and light intensity on nutrients consumption are not uncommon. In the present study, we tried to evaluate the effect of different photoperiod (PP) and photosynthetic photon flux intensity (PPFI) on the nutrient consumption and algal growth of <em>Picochlorum maculatum </em>in shrimp culture effluent. The experiment lasted for 15 days at five different PP cycles (24:0, 18:06, 14:10, 10:14 and 6:18 h light:dark) and four PPFI (50, 100, 150 and 200 µmol m^-2 s^-1) at 28ºC temperature. Every five days the samples were analyzed and results showed that the PP of 18 h light and 6 h dark and 150 µmol m^-2 s^-1of PPFI favouring the growth of <em>P. maculatum</em> with a maximum nutrients consumption (PO₄³⁺ 91%, NO₃- 68%, NO₂- 64%, NH₃⁺ 77%), maximum growth (0.876±0.001 abs) and biomass production (9.93±0.19 g L⁻¹) with highest yield of 9.2% total lipid. Among the photoperiod and photosynthetic photon flux intensity tested, 18:6 h light:dark and 150 µmol m^-2 s^-1 showed the highest nutrients removal and algal growth. This study strongly suggests that <em>P. maculatum</em> PSDK01 was a potential candidate for further commercial development in larger scale.