302
R. Halim
12.4.5 Phycocyanin
Phycocyanin (PC) is a blue phycobiliprotein that is almost exclusively found in
cyanobacteria, such as Spirulina platensis, Galdieria sulphuraria, Limnotrhix sp.
and Synechococcus bacillaris (Cuellar-Bermudez et al. 2015; Furuki et al. 2003;
Gantar et al. 2012; Lawrenz et al. 2011; Papadaki et al. 2017; Rodrigues et al. 2018;
Sørensen et al. 2013). Studies on cyanobacterial PE recovery have used filtered wet
biomass, concentrated wet biomass or dried biomass as their starting material. Spirulina platensis has a relatively thick and robust cell wall that consists of four longitudinal layers composed of a glucose polysaccharide known as β-1,2,-glucan and
peptidoglycan. A mechanical pretreatment (such as ultrasonication, ball milling and
manual grinding) is generally required to rupture cyanobacterial cell walls (Furuki
et al. 2003; Lawrenz et al. 2011; Rodrigues et al. 2018; Sørensen et al. 2013). In
their study examining PC extraction from Synechococcus bacillaris, Lawrenz et al.
(2011) found ultrasonication to be more effective in rupturing the cyanobacterial
cells and liberating PC compared to manual grinding. Phosphate buffers (pH range
= 6 − 7.2), ionic liquids (2-hydroxy ethylammonium acetate or 2-HEAA and 2hydroxy ethylammonium formate or 2-HEAF) and distilled water have previously
been demonstrated as effective extraction solvents for PC (Tables 12.1, 12.5 and
12.6). In Rodrigues et al. (2018), the protic ionic liquid, 2-HEAA/2-HEAF (an
equimolar mixture of 2-HEAA and 2-HEAF), was found to be a more effective PC
extraction solvent than sodium phosphate buffer because of its high diffusional power
and ability to penetrate S. platensis cellular matrix. PC extract has a limited stability
and can be degraded by light, temperature and other microorganisms. It is therefore
critical to ensure that selected recovery procedure does not have any adverse impact
on the pigment’s structure and antioxidant functionality. PC has been shown to be
stable under ultrasonic irradiation (Furuki et al. 2003). The purity of phycocyanin
extract is determined by its A620/A280 value, a ratio that measures the proportion of
PE to other contaminating proteins in the solution (Cuellar-Bermudez et al. 2015).
Extracted PC has to undergo a number of purification steps (refer to Sect. 12.5)
in order to meet the required food-grade (A620/A280 > 0.7) or analytical-grade
(A620/A280 > 4.0) standards of its applications.
12.5 Pigment Purification and Separation
Pigments extracted from microalgal or cyanobacterial biomass generally contain
other impurities that may interfere with their applications and functionalities. These
impurities, e.g. chlorophylls and lipids in carotenoid extracts and proteins in phycobiliprotein extracts, can be separated from the desired pigments with a number of
different chemical and/or chromatographic techniques. Calcium hydroxide precipitation, acid precipitation and column chromatography have previously been used to
remove chlorophylls from astaxanthin and β-carotene extracts (Rammuni et al. 2019).
R. Halim
12.4.5 Phycocyanin
Phycocyanin (PC) is a blue phycobiliprotein that is almost exclusively found in
cyanobacteria, such as Spirulina platensis, Galdieria sulphuraria, Limnotrhix sp.
and Synechococcus bacillaris (Cuellar-Bermudez et al. 2015; Furuki et al. 2003;
Gantar et al. 2012; Lawrenz et al. 2011; Papadaki et al. 2017; Rodrigues et al. 2018;
Sørensen et al. 2013). Studies on cyanobacterial PE recovery have used filtered wet
biomass, concentrated wet biomass or dried biomass as their starting material. Spirulina platensis has a relatively thick and robust cell wall that consists of four longitudinal layers composed of a glucose polysaccharide known as β-1,2,-glucan and
peptidoglycan. A mechanical pretreatment (such as ultrasonication, ball milling and
manual grinding) is generally required to rupture cyanobacterial cell walls (Furuki
et al. 2003; Lawrenz et al. 2011; Rodrigues et al. 2018; Sørensen et al. 2013). In
their study examining PC extraction from Synechococcus bacillaris, Lawrenz et al.
(2011) found ultrasonication to be more effective in rupturing the cyanobacterial
cells and liberating PC compared to manual grinding. Phosphate buffers (pH range
= 6 − 7.2), ionic liquids (2-hydroxy ethylammonium acetate or 2-HEAA and 2hydroxy ethylammonium formate or 2-HEAF) and distilled water have previously
been demonstrated as effective extraction solvents for PC (Tables 12.1, 12.5 and
12.6). In Rodrigues et al. (2018), the protic ionic liquid, 2-HEAA/2-HEAF (an
equimolar mixture of 2-HEAA and 2-HEAF), was found to be a more effective PC
extraction solvent than sodium phosphate buffer because of its high diffusional power
and ability to penetrate S. platensis cellular matrix. PC extract has a limited stability
and can be degraded by light, temperature and other microorganisms. It is therefore
critical to ensure that selected recovery procedure does not have any adverse impact
on the pigment’s structure and antioxidant functionality. PC has been shown to be
stable under ultrasonic irradiation (Furuki et al. 2003). The purity of phycocyanin
extract is determined by its A620/A280 value, a ratio that measures the proportion of
PE to other contaminating proteins in the solution (Cuellar-Bermudez et al. 2015).
Extracted PC has to undergo a number of purification steps (refer to Sect. 12.5)
in order to meet the required food-grade (A620/A280 > 0.7) or analytical-grade
(A620/A280 > 4.0) standards of its applications.
12.5 Pigment Purification and Separation
Pigments extracted from microalgal or cyanobacterial biomass generally contain
other impurities that may interfere with their applications and functionalities. These
impurities, e.g. chlorophylls and lipids in carotenoid extracts and proteins in phycobiliprotein extracts, can be separated from the desired pigments with a number of
different chemical and/or chromatographic techniques. Calcium hydroxide precipitation, acid precipitation and column chromatography have previously been used to
remove chlorophylls from astaxanthin and β-carotene extracts (Rammuni et al. 2019).