Enhancing astaxanthin accumulation in Haematococcus pluvialis by coupled light intensity and nitrogen starvation in column photobioreactors

Abstract

Natural astaxanthin mainly derives from a microalgae producer, Haematococcus pluvialis. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production. However, the different responses to light intensity and nitrogen starvation needed to be analyzed for biomass growth and astaxanthin accumulation. The results showed that the highest level of astaxanthin production was achieved in nitrogen starvation, and was 1.64 times higher than the control group at 11 days. With regard to the optimization of light intensity utilization, it was at 200 µmo/m 2 /s under nitrogen starvation that the highest astaxanthin productivity per light intensity was achieved. In addition, both high light intensity and a nitrogen source had significant effects on multiple indicators. For example, high light intensity had a greater significant effect than a nitrogen source on biomass dry weight, astaxanthin yield and astaxanthin productivity; in contrast, nitrogen starvation was more beneficial for enhancing astaxanthin content per dry weight biomass. The data indicate that high light intensity synergizes with nitrogen starvation to stimulate the biosynthesis of astaxanthin.

Characterization of type-2 diacylglycerol acyltransferases in Haematococcus lacustris reveals their functions and engineering potential in triacylglycerol biosynthesis and possible roles in astaxanthin esterification

“…Our results also revealed that (1) T-AST and T-TAG contents signi cantly increased under HL-W, HL-B, 1/4N, HL-W+1/4N, and HL-B+1/4N conditions, respectively, which was consistent with previous study [34,41], (2) M-AST was the main form which is also proven by previous studies [36][37][38][39], (3) compared to ND stress, HL was more effective in inducing AST accumulation especially under the blue HL condition, which has been testi ed in our previous study [50], (4) coupled HL and ND dual stimulation might be better choices in improving AST and TAG accumulation in H. lacustris ( Fig. 1) [53]. Zhang et al (2018) indicated that HL intensity synergizes with ND can effectively stimulate the biosynthesis of AST [53].…”

“…1) [53]. Zhang et al (2018) indicated that HL intensity synergizes with ND can effectively stimulate the biosynthesis of AST [53]. The previous studies have indicated that AST is predominantly esteri ed with FAs and three forms of AST are present, and the main form of AST is EAST (MAST, 70% and DAST, 25%), which is stored in TAG-rich cytosolic oil bodies (OBs) in H. lacustris [36][37][38][39].…”

“…Haemaococcus lacustris is not only able to produce a substantial amount of TAG but also the highest content of AST under stress conditions, which represents a leading algal candidate of industrial potential [29][30][31][32][33][34][35]. For example, HL and ND stresses can effectively promote the accumulation of AST and TAG in H. lacustris [32][33][34][50][51][52][53]. Our results also revealed that (1) T-AST and T-TAG contents signi cantly increased under HL-W, HL-B, 1/4N, HL-W+1/4N, and HL-B+1/4N conditions, respectively, which was consistent with previous study [34,41], (2) M-AST was the main form which is also proven by previous studies [36][37][38][39], (3) compared to ND stress, HL was more effective in inducing AST accumulation especially under the blue HL condition, which has been testi ed in our previous study [50], (4) coupled HL and ND dual stimulation might be better choices in improving AST and TAG accumulation in H. lacustris ( Fig.…”

“…AST/TAG accumulation and HpDGAT2 genes transcription expression upon HL and ND stresses High light (HL) and nitrogen de cient (ND) stresses can effectively promote the accumulation of AST and TAG in H. lacustris [32][33][34][50][51][52][53]. To understand the relationship between HpDGAT2s expression and TAG/AST biosynthesis, time-course patterns of algal biomass, transcription expression, total AST (T-AST), and total TAG (T-TAG) contents in photoautotrophic cultures of H. lacustris under HL, ND, and double HL+ND stresses were studied ( Fig.…”

Plastid terminal oxidases in Chlamydomonas: connections with astaxanthin and bio-hydrogen production

“…The natural astaxanthin mainly derives from the microalgae producer, Haematococcus. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production [51].…”