classification of algae. It is estimated that tens of millions of tonnes of fucoxanthin
and peridinin are produced naturally in the world’s oceans every year.
Phycobiliproteins are more specialised and restricted to the Cyanophyceae
(blue-green algae, now classified as Cyanobacteria) and Rhodophyceae (red algae)
in which they are localised in specialised aggregated structures, phycobilisomes and
Cryptophyceae. There are two main types of phycobiliproteins, the blue phycocyanin and the red phycoerythrin, but both are usually present, though in differing
proportions. Some ‘blue-green algae’ have a high proportion of phycoerythrin and
are red and some ‘red algae’ have a high proportion of phycocyanin and are
blue-green. The phycobilin prosthetic groups of these pigments are linear tetrapyrroles that are covalently linked to protein via cysteine residues.
Commercial activity is mainly focused on microalgae, which can be grown in
monoculture. This is likely to expand as more commercial applications of these
pigments are devised. Currently, two microalgae are used extensively for the
commercial production of carotenoids. The green algae Dunaliella (D. salina or
D. bardawil) under stress conditions can accumulate a high concentration of
b-carotene, for use as a food colourant and health product. Dunaliella has the
advantage that it tolerates high salt concentrations and can be grown cheaply,
effectively as a monoculture, in large open ponds. Another green algae,
Haematococcus pluvialis, is used to produce astaxanthin (as esters together with
other carotenoids) for use in aquaculture feeds and for cosmetic and health purposes. This, though, is a freshwater species and is more expensive to produce
because it must be grown in photobioreactors under sterile conditions to avoid
contamination. Phycocyanin is under intensive investigation for possible use as a
blue food colourant—safe and stable blue colourants are otherwise elusive—and
phycoerythrin is under consideration as a red food colourant. The intense fluorescence of these phycobilins opens possibilities for their application in clinical
diagnostics, e.g. in immunoassays.
This book is timely. There are many opportunities to develop new applications
for pigments of microalgae and new ways of improving the production of the algae
and their pigments. These aspects are covered extensively in this book, and exciting
prospects are reported. The state of the natural environment, characterised by global
warming due to increasing atmospheric concentration of carbon dioxide, is, however, a major concern for the future of our planet. Natural microalgae are a major
contributor to fixing CO 2 from the atmosphere and generating O 2 , but commercial
production of microalgae may require the input of energy, and the addition of
nutrients, which may lead to eutrophication. The impact of all environmental factors
and the overall environmental balance may be different for different species,
products and culturing conditions, and must, therefore, always be considered.
Prof. George Britton
Formerly at the University of Liverpool
Liverpool, UK
viii
Foreword
and peridinin are produced naturally in the world’s oceans every year.
Phycobiliproteins are more specialised and restricted to the Cyanophyceae
(blue-green algae, now classified as Cyanobacteria) and Rhodophyceae (red algae)
in which they are localised in specialised aggregated structures, phycobilisomes and
Cryptophyceae. There are two main types of phycobiliproteins, the blue phycocyanin and the red phycoerythrin, but both are usually present, though in differing
proportions. Some ‘blue-green algae’ have a high proportion of phycoerythrin and
are red and some ‘red algae’ have a high proportion of phycocyanin and are
blue-green. The phycobilin prosthetic groups of these pigments are linear tetrapyrroles that are covalently linked to protein via cysteine residues.
Commercial activity is mainly focused on microalgae, which can be grown in
monoculture. This is likely to expand as more commercial applications of these
pigments are devised. Currently, two microalgae are used extensively for the
commercial production of carotenoids. The green algae Dunaliella (D. salina or
D. bardawil) under stress conditions can accumulate a high concentration of
b-carotene, for use as a food colourant and health product. Dunaliella has the
advantage that it tolerates high salt concentrations and can be grown cheaply,
effectively as a monoculture, in large open ponds. Another green algae,
Haematococcus pluvialis, is used to produce astaxanthin (as esters together with
other carotenoids) for use in aquaculture feeds and for cosmetic and health purposes. This, though, is a freshwater species and is more expensive to produce
because it must be grown in photobioreactors under sterile conditions to avoid
contamination. Phycocyanin is under intensive investigation for possible use as a
blue food colourant—safe and stable blue colourants are otherwise elusive—and
phycoerythrin is under consideration as a red food colourant. The intense fluorescence of these phycobilins opens possibilities for their application in clinical
diagnostics, e.g. in immunoassays.
This book is timely. There are many opportunities to develop new applications
for pigments of microalgae and new ways of improving the production of the algae
and their pigments. These aspects are covered extensively in this book, and exciting
prospects are reported. The state of the natural environment, characterised by global
warming due to increasing atmospheric concentration of carbon dioxide, is, however, a major concern for the future of our planet. Natural microalgae are a major
contributor to fixing CO 2 from the atmosphere and generating O 2 , but commercial
production of microalgae may require the input of energy, and the addition of
nutrients, which may lead to eutrophication. The impact of all environmental factors
and the overall environmental balance may be different for different species,
products and culturing conditions, and must, therefore, always be considered.
Prof. George Britton
Formerly at the University of Liverpool
Liverpool, UK
viii
Foreword