Astaxanthin production by Haematococcus pluvialis under the phosphate deficiency effect and hight light intensity

Abstract

Astaxanthin is a carotenoid produced by the microalgae Haematococcus pluvialis, which can accumulate up to 3 % of Astaxanthin in dry weight. It is produced under stress conditions, such as increased light and nutrient limitation. The objective is to establish conditions for H. pluvialis to produce astaxanthin using phosphate deficiency in the Rudic medium (RM).
Bioreactors with H. pluvialis UTEX 2505 were used, which contained 20 mg/L (RM1), 30 mg/L (RM2), 40 mg/L (RM3) phosphate, 20 mg/L phosphate with 15,013 mg/L of nitrate (RM4) and a control (RM5). A pH of 6.8, photoperiod 20 h light and 4h darkness and irradiance of 75 luxes in stress phase, white light, temperature of 20 ± 1 °C was used. The fastest growing treatment was RM3 with 9.69 x 105 cell/mL; The ANOVA (95 %) didn’t establish significant differences between treatments (F: 0.272; P: 0.895; df: 4). The highest concentration of chlorophyll was by RM3, with 26.2 µg/ mL (27 pg/cell); no significant differences were established between treatments (F: 1.053; P: 0.392; df: 4). In addition, RM3 obtained higher phosphate consumption (62.5 %); with significant differences between treatments (F: 3.887; P: 0.011; df: 4). The morphological changes demonstrated an accumulation of aplanospores cells for RM1 and RM2 treatments. The RM2 treatment obtained higher astaxanthin with 5,772 µg/mL (6.11 pg/cell); no significant differences were established between treatments (F: 0.622; P: 0.649; df: 4). It was established that phosphate deficiency combined with high light intensity, increases the production of astaxanthin in H. pluvialis.