19 Use of Microalgae Pigments in Aquaculture
485
Most glaucophytes, red algae, some cryptophytes and cyanobacterial species that
grow in natural environment contain high amounts of phycocyanin. The phycocyanins can be grouped into (i) C-phycocyanin (C-PC, λ max ~ 615–620 nm), (ii)
phycoerythrocyanin (PEC, λ max ~ 575 nm) and (iii) R-phycocyanin (R-PC, λ max ~
615 nm) (Chakdar and Pabbi 2017). These blue- or blue- purple-coloured phycobiliproteins are able to absorb light from 580 to 630 nm (Chakdar and Pabbi
2017).
Phycobilins are a group of photoreceptor pigments having similar components
to the porphyrin without a metallic atom and can only be found in Rhodophyta and
cyanobacteria. These phycobilins play an important role in pharmaceutical, food and
textile industries (Udayan et al. 2017).
The most abundant phycobiliprotein in red algae and some cyanobacteria is phycoerythrin. It is a major component of light-harvesting complex and can be categorized according to its absorption bands in the green region of the visible spectrum (480–570 nm) and by intensive fluorescence emissions (575–580 nm). Thus,
these red-coloured proteins are grouped according to their absorption spectra: (i)
B-phycoerythrin (B-PE) (λ max ~ 540–560 nm, (ii) R-phycoerythrin (R-PE) (λ max ~
565, 545 and 495 nm) and (iii) C-phycoerythrin (C-PE) (λ max ~ 563, 543 and 492 nm)
(Chakdar and Pabbi 2017). Among the three types, R-PE is the predominant natural
form.
Phycoerythrocyanin is a cyanobacterial phycobiliprotein which has similar
structures to phycocyanin but similar functions to phycoerythrin (Bryant 1982).
19.6 Structure of Phycobiliproteins
Phycobiliproteins or tetrapyrrole biliproteins are attached on the thylakoid
membranes and are present as phycobilisomes. They lie adjacent to the photosynthetic reaction centre of the PSII in cyanobacteria and red algae. The colour of
phycobiliproteins comes from the covalent bond of prosthetic groups (phycobilins)
(Scheer 1981) attached to different cysteine residues of biliproteins (Sidler 1994).
The phycobilins contain one to four open chain tetrapyrrole chromophore bearing
A, B, C and D pyrrole ring (Grossman et al. 1993; Padyana et al. 2001) having the
ability to capture and transfer the solar photonic energy to the photosystem for use
during photosynthesis.
The core of phycobiliproteins is composed of allophycocyanin from which arise
six rods of varying length consisting of phycocyanins (proximal) and phycoerythrins (distal) (Fig. 19.1). The core units of phycobiliproteins are made up of α(12–20 kDa) and ß- (15–22 kDa) chains (Sinha et al. 1995; Kannaujiya et al. 2014)
in cyanobacteria, whereas in some red algae, γ chain was found. The formation
of functional phycobiliprotein core assembly involves coloured phycobiliproteins
(85%) and colourless linker polypeptides (15%) (Parsiegla et al. 2012). The biosynthesis and stabilization of the phycobiliproteins are achieved by different types of
structural elements which are also known as colourless linker polypeptides that help
485
Most glaucophytes, red algae, some cryptophytes and cyanobacterial species that
grow in natural environment contain high amounts of phycocyanin. The phycocyanins can be grouped into (i) C-phycocyanin (C-PC, λ max ~ 615–620 nm), (ii)
phycoerythrocyanin (PEC, λ max ~ 575 nm) and (iii) R-phycocyanin (R-PC, λ max ~
615 nm) (Chakdar and Pabbi 2017). These blue- or blue- purple-coloured phycobiliproteins are able to absorb light from 580 to 630 nm (Chakdar and Pabbi
2017).
Phycobilins are a group of photoreceptor pigments having similar components
to the porphyrin without a metallic atom and can only be found in Rhodophyta and
cyanobacteria. These phycobilins play an important role in pharmaceutical, food and
textile industries (Udayan et al. 2017).
The most abundant phycobiliprotein in red algae and some cyanobacteria is phycoerythrin. It is a major component of light-harvesting complex and can be categorized according to its absorption bands in the green region of the visible spectrum (480–570 nm) and by intensive fluorescence emissions (575–580 nm). Thus,
these red-coloured proteins are grouped according to their absorption spectra: (i)
B-phycoerythrin (B-PE) (λ max ~ 540–560 nm, (ii) R-phycoerythrin (R-PE) (λ max ~
565, 545 and 495 nm) and (iii) C-phycoerythrin (C-PE) (λ max ~ 563, 543 and 492 nm)
(Chakdar and Pabbi 2017). Among the three types, R-PE is the predominant natural
form.
Phycoerythrocyanin is a cyanobacterial phycobiliprotein which has similar
structures to phycocyanin but similar functions to phycoerythrin (Bryant 1982).
19.6 Structure of Phycobiliproteins
Phycobiliproteins or tetrapyrrole biliproteins are attached on the thylakoid
membranes and are present as phycobilisomes. They lie adjacent to the photosynthetic reaction centre of the PSII in cyanobacteria and red algae. The colour of
phycobiliproteins comes from the covalent bond of prosthetic groups (phycobilins)
(Scheer 1981) attached to different cysteine residues of biliproteins (Sidler 1994).
The phycobilins contain one to four open chain tetrapyrrole chromophore bearing
A, B, C and D pyrrole ring (Grossman et al. 1993; Padyana et al. 2001) having the
ability to capture and transfer the solar photonic energy to the photosystem for use
during photosynthesis.
The core of phycobiliproteins is composed of allophycocyanin from which arise
six rods of varying length consisting of phycocyanins (proximal) and phycoerythrins (distal) (Fig. 19.1). The core units of phycobiliproteins are made up of α(12–20 kDa) and ß- (15–22 kDa) chains (Sinha et al. 1995; Kannaujiya et al. 2014)
in cyanobacteria, whereas in some red algae, γ chain was found. The formation
of functional phycobiliprotein core assembly involves coloured phycobiliproteins
(85%) and colourless linker polypeptides (15%) (Parsiegla et al. 2012). The biosynthesis and stabilization of the phycobiliproteins are achieved by different types of
structural elements which are also known as colourless linker polypeptides that help