248
M. M. Maroneze et al.
Once the USP is completed, the DSP begins. The microalgae biomass DSP
comprises multiple unit processes involving harvesting, extraction, and purification
(Deprá et al. 2018). Following described the technology used to produce carotenoids
and phycobiliproteins from the microalgae H. pluvialis (astaxanthin), D. salina
(β-carotene) and A. platensis (C-phycocyanin).
11.5.1 Astaxanthin Production Process
Currently, only two biological sources compete with synthetic astaxanthin, which
presently dominates the market: the yeast Phaffia rhodozyma and the microalga H.
pluvialis. P. rhodozyma is produced by fermentation and marketed in the form for
salmonid feed powder. The average astaxanthin content in P. rhodozyma is about
8 mg/g, while for H. pluvialis, it is about 60 mg/g. Among natural sources, H.
pluvialis is considered the primary producer of astaxanthin (AstaReal 2019).
The estimated market in 2019 was about 40 USD million for astaxanthin from
H. pluvialis, based on a CAGR of 2.3%. The estimated cost of their production is
about USD 552.0/kg, and the selling price is about USD 2,500/kg (Jacob-Lopes
et al. 2019; Hu 2019). The microalgae H. pluvialis can be cultured photoautotrophically, heterotrophically, or mixotrophically. However, as the astaxanthin biosynthesis
process requires light, a high cellular concentration of astaxanthin (up to ± 5% dw)
is achieved only in photoautotrophic cultures (Kang et al. 2005).
Astaxanthin accumulates in cytosolic lipid bodies under environmental stress
or adverse culture conditions, such as high light, nutrient depletion (especially N
limitation), high temperature, and high salinity (Han et al. 2013). The metabolic
stress conditions regulate the expression of carotenogenic genes. In H. pluvialis, the
expression of caratonegonic genes that encode the enzymes PSY, PDS, lycopene
cyclase (LCY), BKT, and CrtR-b are positively regulated. It is noteworthy that the
strains differ from each other in the build-up of astaxanthin and the gene expression
profile, which can be distinctly regulated in response to the culture conditions applied
(Gao et al. 2015; Ma et al. 2018a; Córdova et al. 2018).
Haematococcus grows as motile bi-flagellated cells under optimal conditions and,
under stress, turn into red cysts. Thus, a continuous culture process is not useful;
instead, a two-stage process must be employed. During cultivation, the microalgae
will undergo three cellular forms: (i) motile biflagellate; (ii) nonmoving palmella;
and (iii) non-motile, haematocysts (Mobin and Alam 2017). In the first stage, flagellated macrozooids rapidly divide under favorable culture conditions, reaching a
high cell density. Posteriorly, under unfavorable conditions, the macrozooids lose
their flagella as they expand cell size and form the nonmoving palmella. When stress
persists, the palmella become transform in haematocysts (aplanospore). At this stage,
significant amounts of astaxanthin are accumulated, which brings red staining to the
cells. Noteworthy, the H. pluvialis hematocysts can be parched and remain inactive
by years and, after, return to life in the microzooid form when exposed to favorable
conditions (Ma et al. 2018b).
M. M. Maroneze et al.
Once the USP is completed, the DSP begins. The microalgae biomass DSP
comprises multiple unit processes involving harvesting, extraction, and purification
(Deprá et al. 2018). Following described the technology used to produce carotenoids
and phycobiliproteins from the microalgae H. pluvialis (astaxanthin), D. salina
(β-carotene) and A. platensis (C-phycocyanin).
11.5.1 Astaxanthin Production Process
Currently, only two biological sources compete with synthetic astaxanthin, which
presently dominates the market: the yeast Phaffia rhodozyma and the microalga H.
pluvialis. P. rhodozyma is produced by fermentation and marketed in the form for
salmonid feed powder. The average astaxanthin content in P. rhodozyma is about
8 mg/g, while for H. pluvialis, it is about 60 mg/g. Among natural sources, H.
pluvialis is considered the primary producer of astaxanthin (AstaReal 2019).
The estimated market in 2019 was about 40 USD million for astaxanthin from
H. pluvialis, based on a CAGR of 2.3%. The estimated cost of their production is
about USD 552.0/kg, and the selling price is about USD 2,500/kg (Jacob-Lopes
et al. 2019; Hu 2019). The microalgae H. pluvialis can be cultured photoautotrophically, heterotrophically, or mixotrophically. However, as the astaxanthin biosynthesis
process requires light, a high cellular concentration of astaxanthin (up to ± 5% dw)
is achieved only in photoautotrophic cultures (Kang et al. 2005).
Astaxanthin accumulates in cytosolic lipid bodies under environmental stress
or adverse culture conditions, such as high light, nutrient depletion (especially N
limitation), high temperature, and high salinity (Han et al. 2013). The metabolic
stress conditions regulate the expression of carotenogenic genes. In H. pluvialis, the
expression of caratonegonic genes that encode the enzymes PSY, PDS, lycopene
cyclase (LCY), BKT, and CrtR-b are positively regulated. It is noteworthy that the
strains differ from each other in the build-up of astaxanthin and the gene expression
profile, which can be distinctly regulated in response to the culture conditions applied
(Gao et al. 2015; Ma et al. 2018a; Córdova et al. 2018).
Haematococcus grows as motile bi-flagellated cells under optimal conditions and,
under stress, turn into red cysts. Thus, a continuous culture process is not useful;
instead, a two-stage process must be employed. During cultivation, the microalgae
will undergo three cellular forms: (i) motile biflagellate; (ii) nonmoving palmella;
and (iii) non-motile, haematocysts (Mobin and Alam 2017). In the first stage, flagellated macrozooids rapidly divide under favorable culture conditions, reaching a
high cell density. Posteriorly, under unfavorable conditions, the macrozooids lose
their flagella as they expand cell size and form the nonmoving palmella. When stress
persists, the palmella become transform in haematocysts (aplanospore). At this stage,
significant amounts of astaxanthin are accumulated, which brings red staining to the
cells. Noteworthy, the H. pluvialis hematocysts can be parched and remain inactive
by years and, after, return to life in the microzooid form when exposed to favorable
conditions (Ma et al. 2018b).