560
Alexandra Galetovi´ c C. and L. Dufossé
stabilize the non-protonated (blue) forms of PC and prevent the formation of protonated forms (green) at low pH. The challenge in the field of phycobiliproteins is to
improve the stability at high temperatures for its use in food in order to guarantee
food safety and overall quality. This can be achieved by using genetic, molecular
tools and biotechnological approaches including extremophile microorganisms.
Keywords Microalgae · Phycoerytrin · Phycocyanin · Allophycocyanin · Food
grade
22.1 Introduction
Phycobiliproteins are classified into three main groups, phycoerythrin (red), phycocyanin (blue), and allophycocyanin (blue). Phycocyanin includes C-phycocyanin
(C-PC) and R-phycocyanin (R-PC). The phycobiliproteins are located on a specialized cellular structure called phycobilisome, they are organized in two domains, and
are attached to the surface of the thylakoid membrane. Phycobilisome consists of
a core of allophycocyanin (APC) surrounded on the periphery by phycocyanin and
phycoerythrin (PE). The organization of the phycobilisome is supported by polypeptides called linkers, which interact with phycocyanin and phycoerythrin to assemble
the rods (Gantt and Conti 1966; Eisele et al. 2000; Samsonoff and MacColl 2001).
The maximum absorption for phycoerythrin is estimated between 540 and 570 nm,
phycocyanin between 610 and 620 nm and allophycocyanin between 650 and 655 nm
(Kannaujiya and Sinha 2016; Kaur et al. 2019).
Phycobiliproteins (PBPs) are antenna pigments composed of apoprotein covalently linked by cysteine residues to tetrapyrrole chromophores, called bilins
(phycocyanobilin for allophycocyanin and C-phycocyanin; phycoerythrobilin for Cphycoerythrin). Phycocyanin is composed of two polypeptide chains (apoprotein):
a small subunit called α containing a chromophore and another subunit called β that
contains two chromophores (Seibert and Connolly 1984; Samsonoff and MacColl
2001; Selig et al. 2018). It is estimated that subunit α has a molecular weight between
12 and 19 kDa and unit β between 14 and 21 kDa (Kaur et al. 2019).
Phycobiliproteins form aggregates. The phycocyanin subunits are found as dimers,
trimer (αβ)3 of about 120 kDa, hexamers (αβ) 6 of about 240 kDa, and even high
molecular weight dodecamers (Samsonoff and MacColl 2001; Selig et al. 2018; Kaur
et al. 2019).
The structure of phycobiliprotein is expressed as a component (pigment) of photosynthesis, bright in color, highly fluorescent (due to phycobilins), and soluble in water
(Kuddus et al. 2013; Kannaujiya and Sinha 2016). In cyanobacteria and red algae, the
energy of light is absorbed by phycoerythrin, then migrates to phycocyanin, to allophycocyanin and finally to chlorophyll, a process that is associated with photosystem
II (Samsonoff and MacColl 2001; Edwards et al. 1997).
At present, it is of industrial-biotechnological interest to use natural dyes mainly
blue pigments with food grade (Fig. 22.1). The main known source is phycocyanin
Alexandra Galetovi´ c C. and L. Dufossé
stabilize the non-protonated (blue) forms of PC and prevent the formation of protonated forms (green) at low pH. The challenge in the field of phycobiliproteins is to
improve the stability at high temperatures for its use in food in order to guarantee
food safety and overall quality. This can be achieved by using genetic, molecular
tools and biotechnological approaches including extremophile microorganisms.
Keywords Microalgae · Phycoerytrin · Phycocyanin · Allophycocyanin · Food
grade
22.1 Introduction
Phycobiliproteins are classified into three main groups, phycoerythrin (red), phycocyanin (blue), and allophycocyanin (blue). Phycocyanin includes C-phycocyanin
(C-PC) and R-phycocyanin (R-PC). The phycobiliproteins are located on a specialized cellular structure called phycobilisome, they are organized in two domains, and
are attached to the surface of the thylakoid membrane. Phycobilisome consists of
a core of allophycocyanin (APC) surrounded on the periphery by phycocyanin and
phycoerythrin (PE). The organization of the phycobilisome is supported by polypeptides called linkers, which interact with phycocyanin and phycoerythrin to assemble
the rods (Gantt and Conti 1966; Eisele et al. 2000; Samsonoff and MacColl 2001).
The maximum absorption for phycoerythrin is estimated between 540 and 570 nm,
phycocyanin between 610 and 620 nm and allophycocyanin between 650 and 655 nm
(Kannaujiya and Sinha 2016; Kaur et al. 2019).
Phycobiliproteins (PBPs) are antenna pigments composed of apoprotein covalently linked by cysteine residues to tetrapyrrole chromophores, called bilins
(phycocyanobilin for allophycocyanin and C-phycocyanin; phycoerythrobilin for Cphycoerythrin). Phycocyanin is composed of two polypeptide chains (apoprotein):
a small subunit called α containing a chromophore and another subunit called β that
contains two chromophores (Seibert and Connolly 1984; Samsonoff and MacColl
2001; Selig et al. 2018). It is estimated that subunit α has a molecular weight between
12 and 19 kDa and unit β between 14 and 21 kDa (Kaur et al. 2019).
Phycobiliproteins form aggregates. The phycocyanin subunits are found as dimers,
trimer (αβ)3 of about 120 kDa, hexamers (αβ) 6 of about 240 kDa, and even high
molecular weight dodecamers (Samsonoff and MacColl 2001; Selig et al. 2018; Kaur
et al. 2019).
The structure of phycobiliprotein is expressed as a component (pigment) of photosynthesis, bright in color, highly fluorescent (due to phycobilins), and soluble in water
(Kuddus et al. 2013; Kannaujiya and Sinha 2016). In cyanobacteria and red algae, the
energy of light is absorbed by phycoerythrin, then migrates to phycocyanin, to allophycocyanin and finally to chlorophyll, a process that is associated with photosystem
II (Samsonoff and MacColl 2001; Edwards et al. 1997).
At present, it is of industrial-biotechnological interest to use natural dyes mainly
blue pigments with food grade (Fig. 22.1). The main known source is phycocyanin