Influence of inoculum size, CO2 concentration and LEDs on the growth of green microalgae Haematococcus pluvialis Flotow

Green microalgae Haematococcus pluvialis is best known for astaxanthin production. The cultivation of H. pluvialis involves two main phases, namely green vegetative stage and cyst stage with astaxanthin accumulation. In fact, the growth of H. pluvialis in the vegetative stage is one of the most important parts in the entire cultivation process. The aim of the study is to investigate the influence of temperature, inoculum size, CO2 concentration and light emitting diodes (LEDs) on the specific growth rate, cell density and dry weight of H. pluvialis in the vegetative stage. Results indicated that the temperature from 25 to 280C and the inoculum size from 3×104 cells.ml-1 were suitable for the growth of the studied strain. Illumination with red light LEDs (630 nm) at 80 μE.m-2.s-1, the highest specific growth rate (μ) was 0.197 day-1 and the maximal density was of 2.87×105 cells.ml-1. A concentration of 5% CO2 (v/v) was the optimal dose for the growth of this strain. Under the condition of both 5% CO2 and illumination with red light LEDs at 80 μE.m-2.s-1, the specific growth rate was 0.242 day-1 and the cell density was 4.28×105cells.ml-1. Illumination with only blue LEDs (430 nm) at 120 μE.m-2.s-1 stimulated the astaxanthin accumulation with a maximum content at 2.36 μg.ml-1.