Sequential Continuous Mixotrophic and Phototrophic Cultivation Might Be a Cost-Effective Strategy for Astaxanthin Production From the Microalga Haematococcus lacustris

Abstract

Although Haematococcus lacustris has been developed for astaxanthin production for decades, the production cost is still high. In order to modify the production processes, we proposed a novel strategy of cultivation, featured by sequential indoor continuous mixotrophic cultivation for the production of green cells followed by outdoor phototrophic induction for astaxanthin accumulation. The continuous mixotrophic cultivation was first optimized indoor, and then the seed culture of mixotrophic cultivation was inoculated into outdoor open raceway ponds for photoinduction. The results showed that mixotrophically grown cultures could efficiently grow without losing their photosynthetic efficiency and yielded higher biomass concentration (0.655 g L−1) and astaxanthin content (2.2% DW), compared to phototrophically grown seed culture controls. This novel strategy might be a promising alternative to the current approaches to advance the production technology of astaxanthin from microalgae.

Mixotrophic cultivation of microalgae for carotenoid production

“…Based on the above findings, a sequential mixotrophy dilution photoinduction strategy (SMDP) was proposed for economical astaxanthin production using glycerol as the carbon source 221 . This idea has been recently further developed by Khazi et al who proved that mixotrophically cultivated seed culture of Haematococcus had at least equal or even better performance than phototrophically cultivated one in ORPs for astaxanthin production 223 …”

“…221 This idea has been recently further developed by Khazi et al who proved that mixotrophically cultivated seed culture of Haematococcus had at least equal or even better performance than phototrophically cultivated one in ORPs for astaxanthin production. 223 Growth media and culture conditions used for mixotrophic cultivation of H. pluvialis influences the biochemical composition of the microalgae. 224 Marinho, Malafaia, de Araújo, da Silva, dos Santos, de Moraes and Gálvez, 224 evaluated the effect of various culture media on the growth, life cycle, biochemical composition and astaxanthin accumulation in H. pluvialis under photoautotrophic and mixotrophic conditions.…”

Astaxanthin production from the microalga Haematococcus lacustris with a dual substrate mixotrophy strategy

“…These results are in agreement with the previous report by Wen et al [21] and also with our previous study. [13] The data on the lipid content of H. lacustris in indoor photoinduction stage was presented in Table 1. The lipid content increased gradually over time during the photoinduction stages of control phototrophic and experimental cultures of H. lacustris.…”

“…[13] High biomass growth rates and astaxanthin contents were achieved through this novel strategy using sodium acetate as a carbon source for green phase cultivation of Haematococcus. [13] Although acetate is an efficient and inexpensive substrate for Haematococcus, it can be harmful and toxic to cell growth of the microalga at high concentrations. [14] Therefore, it is might be constructivie to develop new technologies that use other carbon sources individually or together with acetate as mixed carbon sources, to achieve higher cell growth and biomass concentrations.…”

“…[ 7–10 ] Sodium acetate (NaAc) can significantly enhance cell growth and astaxanthin accumulation by increasing respiratory rates and decreasing photoinhibition in the cells. [ 11,12 ] In one of our recent studies, we established a state‐of‐the‐art strategy of mixotrophic cultivation for astaxanthin production from Haematococcus , which we named as “sequential continuous mixotrophic and phototrophic cultivation.” [ 13 ] High biomass growth rates and astaxanthin contents were achieved through this novel strategy using sodium acetate as a carbon source for green phase cultivation of Haematococcus . [ 13 ] Although acetate is an efficient and inexpensive substrate for Haematococcus , it can be harmful and toxic to cell growth of the microalga at high concentrations.…”