Enhanced growth rate and lipid production of freshwater microalgae by adopting two-stage cultivation system under diverse light and nutrients conditions

Abstract

This study aims to investigate the growth behaviour and lipid production of Chlorella vulgaris (a microalga) by manipulating the effect of light and nutrients. In our presumptive two-staged growth model, C. vulgaris was first grown under low levels of light and nutrients in stage 1 and then in stage 2 under several combinations of light and nutrients, Nt-/Lt-minimum nutrients and minimum light as control; Nt+/Lt+ maximum light and maximum nutrients; Nt+/Lt-maximum nutrients and minimum light, and Nt-/Lt+ minimum nutrients and maximum light. Doubling time reduced from 46.8 +/- 02 hours in control (Nt-/Lt-) to 36.1 +/- 04 in Nt-/Lt+ and 37.7 +/- 0.9 in Nt+/Lt- and further down to 25.2 +/- 03 h in Nt+/Lt+. The highest lipid contents were found in Nt-/Lt+ (9.5 +/- 0.14%) followed by Nt+/Lt+ (8.6 +/- 0.2%), Nt+/Lt-(6.4 +/- 0.12%) and Nt-/Lt-(6.1 +/- 0.22%), respectively. The maximum biomass (909 mg/L) was found in Nt+/Lt+ likely suggesting that limited growth in control was attributed to the limitation of nutrients and light. Incremental addition of light and nutrients is suggested for enhanced growth rate, biomass and lipid production.