ii i
ABSTRACT
Spirulina are multicellular and filamentous blue-green microalgae belonging to two separate genera
Spirulina and Arthrospira and consists of about 15 species. Of these, Arthrospira platensis is the most
common and widely available spirulina and most of the published research and public health decision
refers to this specific species. It grows in water, can be harvested and processed easily and has
significantly high macro- and micronutrient contents. In many countries of Africa, it is used as human
food as an important source of protein and is collected from natural water, dried and eaten. It has gained
considerable popularity in the human health food industry and in many countries of Asia it is used as
protein supplement and as human health food. Spirulina has been used as a complementary dietary
ingredient of feed for poultry and increasingly as a protein and vitamin supplement to aquafeeds.
Spirulina appears to have considerable potential for development, especially as a small-scale crop for
nutritional enhancement, livelihood development and environmental mitigation. FAO fisheries statistics
(FishStat) hint at the growing importance of this product. Production in China was first recorded at 19 080
tonnes in 2003 and rose sharply to 41 570 tonnes in 2004, worth around US$7.6 millions and US$16.6
millions, respectively. However, there are no apparent figures for production in the rest of the world. This
suggests that despite the widespread publicity about spirulina and its benefits, it has not yet received the
serious consideration it deserves as a potentially key crop in coastal and alkaline areas where traditional
agriculture struggles, especially under the increasing influence of salination and water shortages.
There is therefore a role for both national governments – as well as intergovernmental organizations – to
re-evaluate the potential of spirulina to fulfill both their own food security needs as well as a tool for their
overseas development and emergency response efforts. International organization(s) working with
spirulina should consider preparing a practical guide to small-scale spirulina production that could be
used as a basis for extension and development methodologies. This small-scale production should be
orientated towards: (i) providing nutritional supplements for widespread use in rural and urban
communities where the staple diet is poor or inadequate; (ii) allowing diversification from traditional
crops in cases where land or water resources are limited; (iii) an integrated solution for waste water
treatment, small-scale aquaculture production and other livestock feed supplement; and (iv) as a shortand
medium-term solution to emergency situations where a sustainable supply of high protein/high
vitamin foodstuffs is required.
A second need is a better monitoring of global spirulina production and product flows. The current
FishStat entry which only includes China is obviously inadequate and the reason why other countries are
not included investigated. Furthermore, it would be beneficial if production was disaggregated into
different scales of development, e.g. intensive, semi-intensive and extensive. This would allow a better
understanding of the different participants involved and assist efforts to combine experience and
knowledge for both the further development of spirulina production technologies and their replication in
the field. A third need is to develop clear guidelines on food safety aspects of spirulina so that human
health risks can be managed during production and processing. Finally, it would be useful to have some
form of web-based resource that allows the compilation of scientifically robust information and statistics
for public access. There are already a number of spirulina-related websites (e.g. www.spirulina.com,
www.spirulinasource.com) – whilst useful resources, they lack the independent scientific credibility that
is required.
Habib, M.A.B.; Parvin, M.; Huntington, T.C.; Hasan, M.R.
A review on culture, production and use of spirulina as food for humans and feeds for domestic animals
and fish.
FAO Fisheries and Aquaculture Circular. No. 1034. Rome, FAO. 2008. 33p.1
1 INTRODUCTION AND SCOPE
Spirulina are multicellular and filamentous blue-green algae that has gained considerable popularity in the
health food industry and increasingly as a protein and vitamin supplement to aquaculture diets. It grows
in water, can be harvested and processed easily and has very high macro- and micro-nutrient contents. It
has long been used as a dietary supplement by people living close to the alkaline lakes where it is
naturally found – for instance those living adjacent to Lake Chad in the Kanem region have very low
levels of malnutrition, despite living on a spartan millet-base diet. This traditional food, known as dihé,
was rediscovered in Chad by a European scientific mission, and is now widely cultured throughout the
world. In many countries of Africa, it is still used as human food as a major source of protein and is
collected from natural water, dried and eaten. It has gained considerable popularity in the human health
food industry and in many countries of Asia it is used as protein supplement and as health food.
Figure 1: Spirulina and its sales as dried cakes in Chad
Spirulina Spirulina cakes (dihé)
on sale in a local
market in Chad
Source: www.spirulinasource.com
Spirulina has been used as a complementary dietary ingredient of feed for fish, shrimp and poultry, and
increasingly as a protein and vitamin supplement to aquafeeds. China is using this micro-alga as a partial
substitute of imported forage to promote the growth, immunity and viability of shrimp. There has also
been comprehensive research on the use of spirulina as aquaculture feed additives in Japan.
During the sixtieth session of the United Nations General Assembly (Second Committee, Agenda item
52), a revised draft resolution on the “Use of spirulina to combat hunger and malnutrition and help
achieve sustainable development” was submitted by Burundi, Cameroon, Dominican Republic,
Nicaragua and Paraguay. As a follow up of this resolution, FAO was requested to prepare a draft position
paper on spirulina so as to have a clearer understanding on its use and to convey FAO’s position on this.
The primary objective of this review is therefore to assess and evaluate the existing knowledge on the
culture, production and use of spirulina for both human consumption and animal feeds.2
2 HISTORICAL BACKGROUND ON THE USE OF SPIRULINA AS
HUMAN FOOD AND ANIMAL FEED
Spirulina is a primitive organism originating some 3.5 billion years ago that has established the ability to
utilize carbon dioxide dissolved in seawater as a nutrient source for their reproduction. Spirulina is a
photosynthesizing cyanophyte (blue-green algae) that grows vigorously in strong sunshine under high
temperatures and highly alkaline conditions.
2.1 Historical use
In the sixteenth century, when the Spanish invaders conquered Mexico, they discovered that the Aztecs
living in the Valley of Mexico in the capital Tenochtitlan were collecting a “new food” from the lake
(Sasson, 1997). Spanish chroniclers described fishermen with fine nets collecting this blue coloured
“techuitlatl” from the lagoons and making a blue-green cake from it. Other legends say Aztec messenger
runners took spirulina on their marathons. Techuitlatl was mentioned by naturalists until the end of the
sixteenth century, but not after that, probably reflecting the loss of the lakes as they were drained for
urban and agricultural development. The only remnant today, Lake Texcoco, still has a living algae
spirulina population.
The Kanembu population living along the shores of Lake Chad collects the wet algae in clay pots, drain
out the water through bags of cloth and spread out the algae in the sandy shore of the lake for sun drying.
The semi-dried algae is then cut into small squares and taken to the villages, where the drying is
completed on mats in the sun (Abdulqader, Barsanti and Tredici, 2000). When dry, women take these
algae cakes for sale in the local market. Dihé is crumbled and mixed with a sauce of tomatoes and
peppers, and poured over millet, beans, fish or meat and is eaten by the Kanembu in 70 percent of their
meals (www.spirulinasource.com). Pregnant women eat dihé cakes directly because they believe its dark
colour will screen their unborn baby from the eyes of sorcerers (Ciferri, 1983). Spirulina is also applied
externally as a poultice for treating certain diseases. Abdulqader, Barsanti and Tredici (2000) further noted
that the local trading value of the dihé annually harvested from Lake Kossorom in Chad (about 40 tonnes)
amounts to more than US $100,000, which represents an important contribution to the economy of the
area.
2.2 Rediscovery of spirulina
In 1940, a French phycologist Dangeard published a report on the consumption of dihé by the Kanembu
people near Lake Chad (Dangeard, 1940). Dangeard also noted these same algae populated a number of
lakes in the Rift Valley of East Africa, and was the main food for the flamingos living around those lakes.
Twenty-five years later during 1964-65, a botanist on a Belgian Trans-Saharan expedition, Jean Léonard,
reported finding a curious greenish, edible cakes being sold in native markets of Fort-Lamy (now
N’Djamena) in Chad (Léonard, 1966). When locals said these cakes came from areas near Lake Chad,
Léonard recognized the connection between the algal blooms and dried cakes sold in the market.
In 1967 spirulina was established as a “wonderful future food source” in the International Association of
Applied Microbiology (Sasson, 1997). Analysis of the nutritional properties of spirulina showed first and
foremost an exceptionally high protein content, of the order of 60–70 percent of its dry weight; it also
showed the excellent quality of its proteins (balanced essential amino acid content). This first data was
enough to launch many research projects for industrial purposes in the 1970s, because micro-organisms
(yeast, chlorella, spirulina, some bacteria and moulds) seemed at that time to be the most direct route to
inexpensive proteins – the iconic “single cell proteins”.
At the same time when Léonard rediscovered spirulina in Africa, a request was received from a company
named Sosa-Texcoco Ltd by the “Institut français du pétrole” to study a bloom of algae occurring in the
evaporation ponds of their sodium bicarbonate production facility in a lake near Mexico City. As a result,
the first systematic and detailed study of the growth requirements and physiology of spirulina was
performed. This study, which was a part of Ph.D. thesis by Zarrouk (1966), was the basis for establishing
the first large-scale production plant of spirulina (Sasson, 1997).
While finally no micro-organism fulfilled its promise of cheap protein, spirulina continued to give rise to3
3 GENERAL CHARACTERISTICS OF SPIRULINA
3.1 Morphology and taxonomy
3.1.1 Morphology
Spirulina is symbiotic, multicellular and filamentous blue-green microalgae with symbiotic bacteria that
fix nitrogen from air. Spirulina can be rod- or disk-shaped. Their main photosynthetic pigment is
phycocyanin, which is blue in colour. These bacteria also contain chlorophyll a and carotenoids. Some
contain the pigment phycoythrin, giving the bacteria a red or pink colour. Spirulina are photosynthetic
and therefore autotrophic. Spirulina reproduce by binary fission.
The helical shape of the filaments (or trichomes) is characteristic of the genus and is maintained only in a
liquid environment or culture medium. The presence of gas-filled vacuoles in the cells, together with the
helical shape of the filaments, result in floating mats. The trichomes have a length of 50 to 500 μm and a
width of 3 to 4 μm. However, cyanobacteria have a cell wall similar to that of Gram-negative bacteria:
they contain peptidoglucan, a lysozyme-sensitive heteropolymer that confers shape and osmotic
protection to the cell, in addition to other material not sensitive to lysozyme. In the 1970s, sphaeroplasts,
produced by disintegration of their cell wall by enzymatic treatment, were isolated from Oscillatoria
formosa, Fremyella dipplosiphon, Plectonema calothricoides and Synecchoccus lividus, as well as from
Anabaena ambique and Anacystis nidulans. In the case of spirulina, protoplasts had been obtained by
several researchers. For example, Abo-Shady et al. (1992) succeeded in obtaining protoplasts of Spirulina
platensis with high efficiency by lysozyme treatment at the exponential phase of algal growth at 30 °C
under illumination with 1 450 lux/m2/second. The body surface of spirulina is smooth and without
covering so it easily digestible by simple enzymatic systems.
3.1.2 Taxonomy
In 1827, P.J. Turpin isolated spirulina from a freshwater sample (Ciferri, 1983). In 1844, Wittrock and
Nordstedt reported the presence near the city of Montevideo of a helical, septal and green-blue
microalgae named Spirulina jenneri f. platensis. But it was not until 1852 that the first taxonomic report
written by Stizenberger appeared. He gave this new genus the name Arthrospira based on the septa
presence, helical form and multicellular structure. Gomont confirmed Stizenberger’s studies in 1892. This
author attributed the aseptate form to the Spirulina genus, and the septal form to the Arthrospira genus.
Geitler in 1932, because of the common helical morphology, reunified the members of the two genera
under the designation Spirulina without considering the septum presence, only morphological similarity.
In 1989, these micro-organisms were separately classified into two genera Spirulina and Arthrospira; this
classification is currently accepted (Tomaselli, Palandri and Tredici, 1996; Sánchez et al., undated).
Arthrospira maxima and A. platensis are the most important species in this genus and among these existed
taxonomic differences in filaments, vacuoles and external cover or capsule regularity of each filament
(Tomaselli, 1997). The worldwide investigation on microalgae has been carried out under the name of
“spirulina”; this common designation between scientists and consumers has proved difficult to change.
The microalgae under discussion belongs to the genus Arthrospira, but it will probably be called Spirulina
for some time. For the purpose of this report we refer to both collectively as “spirulina”.
The systematic position of cyanobacteria has been a matter of discussion, as these photosynthetic
organisms were first considered algae. In 1962, a distinction between prokaryotes and eukaryotes was
clearly established. The main difference is based upon the presence of cell organelles enveloped by a
phospholipidic membrane in eukaryotes. Stanier and Van Neil (1962) incorporated green-blue algae into
the prokaryote kingdom and proposed to call these micro-organisms cyanobacteria. This designation was
accepted and first published in 1974 in the Bergey's Manual of Determinative Bacteriology (Guglielmi,
Rippka and Tandeau De Marsac, 1993).
3.2 Natural habitat, source and growth
Besides Lake Texcoco, the largest spirulina lakes are in Central Africa around Lakes Chad and Niger, and
in East Africa along the Great Rift Valley. Under normal water conditions, Spirulina may be one of many
algal species. Lakes Bodou and Rombou in Chad have a stable monoculture of spirulina dating back
centuries. It is also a major species in Kenya's lakes Nakuru and Elementeita and Ethiopia's lakes
Aranguadi and Kilotes. Spirulina thrives in alkaline lakes where it is difficult or impossible for other micro
research and increasing production, reflecting its perceived nutritional assets (Falquet, 2000).4
organisms to survive (Kebede and Ahlgren, 1966). In natural lakes, the limited supply of nutrients usually
regulates growth cycles. New nutrients come from either an upwelling from inside the waterbodies,
influxes of nutrients from rivers or from pollution. The algae population grows rapidly, reaches a
maximum density, and then dies off when nutrients are exhausted. A new seasonal cycle begins when
decomposed algae release their nutrients or when more nutrients flow into the lake.
Spirulina is found in soil, marshes, freshwater, brackish water, seawater and thermal springs. Alkaline,
saline water (>30 g/l) with high pH (8.5–11.0) favour good production of spirulina, especially where
there is a high level of solar radiation at altitude in the tropics. Spirulina platensis and Spirulina maxima
thrive in highly alkaline lakes of Africa and Mexico where the cyanobacteria population is practically
monospecific. The higher the pH and the conductivity of the water, the greater is the likely predominance
of Spirulina spp. This is the case in the lakes of the lakes of the Rift Valley of eastern Africa, where pH can
reach values close to 11 and sodium carbonate is abundant. Spirulina platensis was isolated from waters
containing from 85 to 270 g of salt per litre, and optimum growth occurred between 20 and 70 g of salt
per litre. A relatively high cytoplasmic pH (4.2 to 8.5) may account for the ability of this micro-organism
to utilize ammonia as a source of nitrogen at high alkaline pH values (Sasson, 1997).
Spirulina is, like most cyanobacteria, an obligate photoautotroph, i.e. it cannot grow in the dark on media
containing organic carbon compounds. It reduces carbon dioxide in the light and assimilates mainly
nitrates. The main assimilation product of spirulina photosynthesis is glycogen. Spirulina shows an
optimum growth between 35 and 37 °C under laboratory conditions. Outdoors, it seems that an increase
in temperature up to 39 °C for a few hours does not harm the blue-green alga, or its photosynthetic
ability. Thermophilic or thermotolerant strains of spirulina can be cultivated at temperatures between 35
and 40 °C. Such a property has the advantage of eliminating microbial mesophilic contaminants. The
minimum temperature at which growth of spirulina takes place is around 15 °C during the day. At night,
spirulina can tolerate relatively low temperatures. The resistance of spirulina to ultraviolet rays seems to
be rather high (Richmond, 1986).
3.3 Biochemical composition
The basic biochemical composition of spirulina can be summarized as follows:
Protein: Spirulina contains unusually high amounts of protein, between 55 and 70 percent by dry weight,
depending upon the source (Phang et al., 2000). It is a complete protein, containing all essential amino
acids, though with reduced amounts of methionine, cystine, and lysine, as compared to standard proteins
such as that from meat, eggs, or milk; it is, however, superior to all standard plant protein, such as that
from legumes.
Essential fatty acids: Spirulina has a high amount of polyunsaturated fatty acids (PUFAs), 1.5–2.0 percent
of 5–6 percent total lipid. In particular spirulina is rich in γ-linolenic acid (36 percent of total PUFAs), and
also provides γ-linolenic acid (ALA), linoleic acid (LA, 36 percent of total ), stearidonic acid (SDA),
eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA).
Vitamins: Spirulina contains vitamin B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B6 (pyridoxine), B9
(folic acid), B12 (cyanocobalamin), vitamin C, vitamin D and vitamin E.
Minerals: Spirulina is a rich source of potassium, and also contains calcium, chromium, copper, iron,
magnesium, manganese, phosphorus, selenium, sodium and zinc.
Photosynthetic pigments: Spirulina contains many pigments including chlorophyll a, xanthophyll, betacarotene,
echinenone, myxoxanthophyll, zeaxanthin, canthaxanthin, diatoxanthin, 3-hydroxyechinenone,
beta-cryptoxanthin, oscillaxanthin, plus the phycobiliproteins c-phycocyanin and allophycocyanin.
Detailed biochemical composition analyses have been conducted of spirulina grown either under
laboratory conditions, collected in natural condition or in mass culture system using different agroindustrial
waste effluent. This was found to vary in response to the salinity of the growing medium –
Vonshak et al. (1996) reported that salt-adapted cells had a modified biochemical composition with a
reduced protein and chlorophyll content, and increased carbohydrate content. However the following
provides a review of the literature on the broad composition of spirulina.5
3.3.1 Proximate composition
Spirulina has high quality protein content (59–65 percent), which is more than other commonly used
plant sources such as dry soybeans (35 percent), peanuts (25 percent) or grains (8–10 percent). A special
value of spirulina is that it is readily digested due to the absence of cellulose in its cell walls (as it is the
case for eukaryotic green microalgae such as Chlorella, Ankistrodesmus, Selenastrum, Scenedesmus):
after 18 hours more than 85 percent of its protein is digested and assimilated (Sasson, 1997). The
composition of commercial spirulina powder is 60 percent protein, 20 percent carbohydrate, 5 percent
fats, 7 percent minerals, and 3–6 percent moisture, making it a low-fat, low calorie, cholesterol-free
source of protein.
Table 1: Various proximate analysis results of spirulina (% dry matter)
Component FOI, France SAC,
Thailand
IPGSR,
Malaysia
BAU,
Bangladesh
Crude protein 65 55–70 61 60
Soluble carbohydrate 19 14
Crude lipid 4 5–7 6 7
Crude fiber 3 5–7
Ash 3 3–6 9 11
Moisture 4–6 6 9
Nitrogen free extract (NFE) 15–20 4 17
FOI = French Oil Institute; SAC = Siam Algae Co. Ltd; IPGSR = Institute of Post-graduate Studies and Research laboratory,
University of Malaya; BAU = Bangladesh Agricultural University
3.3.2 Amino acids
Spirulina protein has a balanced composition of amino acids, with concentrations of methionine,
tryptophan and other amino acids almost similar to those of casein although this depends upon the
culture media used.
Table 2: Amino acid composition of spirulina (g/100 g)
Source
Lysine
Phenylalanine
Tyrosine
Leucine
Methionine
Glutamic acid
Aspartic acid
Tryptophan
Cystine
Siam
Algae
Co. Ltd.,
Thailand
2.60–3.30 2.60–3.30 2.60–3.30 5.90–6.50 1.30–2.00 7.30–9.50 5.20–6.00 1.00–1.60 0.50–0.70
IPGSR,
Malaysia
4.63±0.07 4.10±0.08 3.42±0.10 8.37±0.13 2.75±0.05 7.04±0.14 5.37±0.11 1.98±0.05 0.6±0.03
Table 2: Continued
Source
Serine
Arginine
Histidine
Threonine
Proline
Valine
Isoleucine7
when cells exhibited the higher polysaccharide content. In the case of Cr VI, the highest gmax exhibited
by cells cultivated in Zarrouk medium and showing the higher protein content (at pH 2.0). But pH did not
affect the adsorption of Pb II in the range of 3 to 5.5, nor of Cd in the range of 4 to 7. For Cr II, adsorption
observed only at a pH equal to 2.0 or lower.
3.3.5 Chelating of toxic minerals (neutralization of toxic minerals)
Spirulina has a unique quality to detoxify (neutralize) or to chelate toxic minerals, a characteristic that is
not yet confirmed in any other microalgae (Maeda and Sakaguchi, 1990; Okamura and Aoyama, 1994).
Spirulina can be used to detoxify arsenic from water and food. It also may be used to chelatize or detoxify
the poisonous effect of heavy metals (minerals) from water, food and environment. Beijing University has
extracted bioactive molecules from spirulina which could neutralize or detoxify the toxic and poisonous
effect of heavy metals, and which showed anti-tumor activity. Several institutions in China are focusing on
biomolecules which show anti-tumor, anti-age and anti-radiation properties (Liu, Guo and Ruan, 1991; Li
and Qi, 1997).
3.3.6 β-carotene and vitamins
The β-carotene, B-group vitamin, vitamin E, iron, potassium and chlorophyll available in the spirulina can
promote the metabolism of carbohydrate, fats, protein, alcohol, and the reproduction of skin, muscle and
mucosa. Spirulina contains large amounts of natural β-carotene and this β-carotene is converted into
vitamin A. According to the findings of the National Cancer Institute, United States of America, an intake
of 6.0 mg β-carotene daily may be effective in minimizing the risk of cancer. If anybody takes 4.0 g
spirulina daily, that is sufficient to get 6 mg β-carotene. At the same time, sufficient amount of B-group
vitamins, iron and calcium will be obtained. However, these nutrients obtained from 4.0 g of spirulina are
equivalent to or more than those obtained by eating more than 100 g of terrestrial bright-coloured
vegetables.
Alanine
Glycine
IPGSR,
Malaysia
3.84±0.06 4.94±0.07 2.81±0.06 3.35±0.06 4.11±0.05 4.02±0.06 3.85±0.10 10.81±0.14 6.66±0.10
ABSTRACT
Spirulina are multicellular and filamentous blue-green microalgae belonging to two separate genera
Spirulina and Arthrospira and consists of about 15 species. Of these, Arthrospira platensis is the most
common and widely available spirulina and most of the published research and public health decision
refers to this specific species. It grows in water, can be harvested and processed easily and has
significantly high macro- and micronutrient contents. In many countries of Africa, it is used as human
food as an important source of protein and is collected from natural water, dried and eaten. It has gained
considerable popularity in the human health food industry and in many countries of Asia it is used as
protein supplement and as human health food. Spirulina has been used as a complementary dietary
ingredient of feed for poultry and increasingly as a protein and vitamin supplement to aquafeeds.
Spirulina appears to have considerable potential for development, especially as a small-scale crop for
nutritional enhancement, livelihood development and environmental mitigation. FAO fisheries statistics
(FishStat) hint at the growing importance of this product. Production in China was first recorded at 19 080
tonnes in 2003 and rose sharply to 41 570 tonnes in 2004, worth around US$7.6 millions and US$16.6
millions, respectively. However, there are no apparent figures for production in the rest of the world. This
suggests that despite the widespread publicity about spirulina and its benefits, it has not yet received the
serious consideration it deserves as a potentially key crop in coastal and alkaline areas where traditional
agriculture struggles, especially under the increasing influence of salination and water shortages.
There is therefore a role for both national governments – as well as intergovernmental organizations – to
re-evaluate the potential of spirulina to fulfill both their own food security needs as well as a tool for their
overseas development and emergency response efforts. International organization(s) working with
spirulina should consider preparing a practical guide to small-scale spirulina production that could be
used as a basis for extension and development methodologies. This small-scale production should be
orientated towards: (i) providing nutritional supplements for widespread use in rural and urban
communities where the staple diet is poor or inadequate; (ii) allowing diversification from traditional
crops in cases where land or water resources are limited; (iii) an integrated solution for waste water
treatment, small-scale aquaculture production and other livestock feed supplement; and (iv) as a shortand
medium-term solution to emergency situations where a sustainable supply of high protein/high
vitamin foodstuffs is required.
A second need is a better monitoring of global spirulina production and product flows. The current
FishStat entry which only includes China is obviously inadequate and the reason why other countries are
not included investigated. Furthermore, it would be beneficial if production was disaggregated into
different scales of development, e.g. intensive, semi-intensive and extensive. This would allow a better
understanding of the different participants involved and assist efforts to combine experience and
knowledge for both the further development of spirulina production technologies and their replication in
the field. A third need is to develop clear guidelines on food safety aspects of spirulina so that human
health risks can be managed during production and processing. Finally, it would be useful to have some
form of web-based resource that allows the compilation of scientifically robust information and statistics
for public access. There are already a number of spirulina-related websites (e.g. www.spirulina.com,
www.spirulinasource.com) – whilst useful resources, they lack the independent scientific credibility that
is required.
Habib, M.A.B.; Parvin, M.; Huntington, T.C.; Hasan, M.R.
A review on culture, production and use of spirulina as food for humans and feeds for domestic animals
and fish.
FAO Fisheries and Aquaculture Circular. No. 1034. Rome, FAO. 2008. 33p.1
1 INTRODUCTION AND SCOPE
Spirulina are multicellular and filamentous blue-green algae that has gained considerable popularity in the
health food industry and increasingly as a protein and vitamin supplement to aquaculture diets. It grows
in water, can be harvested and processed easily and has very high macro- and micro-nutrient contents. It
has long been used as a dietary supplement by people living close to the alkaline lakes where it is
naturally found – for instance those living adjacent to Lake Chad in the Kanem region have very low
levels of malnutrition, despite living on a spartan millet-base diet. This traditional food, known as dihé,
was rediscovered in Chad by a European scientific mission, and is now widely cultured throughout the
world. In many countries of Africa, it is still used as human food as a major source of protein and is
collected from natural water, dried and eaten. It has gained considerable popularity in the human health
food industry and in many countries of Asia it is used as protein supplement and as health food.
Figure 1: Spirulina and its sales as dried cakes in Chad
Spirulina Spirulina cakes (dihé)
on sale in a local
market in Chad
Source: www.spirulinasource.com
Spirulina has been used as a complementary dietary ingredient of feed for fish, shrimp and poultry, and
increasingly as a protein and vitamin supplement to aquafeeds. China is using this micro-alga as a partial
substitute of imported forage to promote the growth, immunity and viability of shrimp. There has also
been comprehensive research on the use of spirulina as aquaculture feed additives in Japan.
During the sixtieth session of the United Nations General Assembly (Second Committee, Agenda item
52), a revised draft resolution on the “Use of spirulina to combat hunger and malnutrition and help
achieve sustainable development” was submitted by Burundi, Cameroon, Dominican Republic,
Nicaragua and Paraguay. As a follow up of this resolution, FAO was requested to prepare a draft position
paper on spirulina so as to have a clearer understanding on its use and to convey FAO’s position on this.
The primary objective of this review is therefore to assess and evaluate the existing knowledge on the
culture, production and use of spirulina for both human consumption and animal feeds.2
2 HISTORICAL BACKGROUND ON THE USE OF SPIRULINA AS
HUMAN FOOD AND ANIMAL FEED
Spirulina is a primitive organism originating some 3.5 billion years ago that has established the ability to
utilize carbon dioxide dissolved in seawater as a nutrient source for their reproduction. Spirulina is a
photosynthesizing cyanophyte (blue-green algae) that grows vigorously in strong sunshine under high
temperatures and highly alkaline conditions.
2.1 Historical use
In the sixteenth century, when the Spanish invaders conquered Mexico, they discovered that the Aztecs
living in the Valley of Mexico in the capital Tenochtitlan were collecting a “new food” from the lake
(Sasson, 1997). Spanish chroniclers described fishermen with fine nets collecting this blue coloured
“techuitlatl” from the lagoons and making a blue-green cake from it. Other legends say Aztec messenger
runners took spirulina on their marathons. Techuitlatl was mentioned by naturalists until the end of the
sixteenth century, but not after that, probably reflecting the loss of the lakes as they were drained for
urban and agricultural development. The only remnant today, Lake Texcoco, still has a living algae
spirulina population.
The Kanembu population living along the shores of Lake Chad collects the wet algae in clay pots, drain
out the water through bags of cloth and spread out the algae in the sandy shore of the lake for sun drying.
The semi-dried algae is then cut into small squares and taken to the villages, where the drying is
completed on mats in the sun (Abdulqader, Barsanti and Tredici, 2000). When dry, women take these
algae cakes for sale in the local market. Dihé is crumbled and mixed with a sauce of tomatoes and
peppers, and poured over millet, beans, fish or meat and is eaten by the Kanembu in 70 percent of their
meals (www.spirulinasource.com). Pregnant women eat dihé cakes directly because they believe its dark
colour will screen their unborn baby from the eyes of sorcerers (Ciferri, 1983). Spirulina is also applied
externally as a poultice for treating certain diseases. Abdulqader, Barsanti and Tredici (2000) further noted
that the local trading value of the dihé annually harvested from Lake Kossorom in Chad (about 40 tonnes)
amounts to more than US $100,000, which represents an important contribution to the economy of the
area.
2.2 Rediscovery of spirulina
In 1940, a French phycologist Dangeard published a report on the consumption of dihé by the Kanembu
people near Lake Chad (Dangeard, 1940). Dangeard also noted these same algae populated a number of
lakes in the Rift Valley of East Africa, and was the main food for the flamingos living around those lakes.
Twenty-five years later during 1964-65, a botanist on a Belgian Trans-Saharan expedition, Jean Léonard,
reported finding a curious greenish, edible cakes being sold in native markets of Fort-Lamy (now
N’Djamena) in Chad (Léonard, 1966). When locals said these cakes came from areas near Lake Chad,
Léonard recognized the connection between the algal blooms and dried cakes sold in the market.
In 1967 spirulina was established as a “wonderful future food source” in the International Association of
Applied Microbiology (Sasson, 1997). Analysis of the nutritional properties of spirulina showed first and
foremost an exceptionally high protein content, of the order of 60–70 percent of its dry weight; it also
showed the excellent quality of its proteins (balanced essential amino acid content). This first data was
enough to launch many research projects for industrial purposes in the 1970s, because micro-organisms
(yeast, chlorella, spirulina, some bacteria and moulds) seemed at that time to be the most direct route to
inexpensive proteins – the iconic “single cell proteins”.
At the same time when Léonard rediscovered spirulina in Africa, a request was received from a company
named Sosa-Texcoco Ltd by the “Institut français du pétrole” to study a bloom of algae occurring in the
evaporation ponds of their sodium bicarbonate production facility in a lake near Mexico City. As a result,
the first systematic and detailed study of the growth requirements and physiology of spirulina was
performed. This study, which was a part of Ph.D. thesis by Zarrouk (1966), was the basis for establishing
the first large-scale production plant of spirulina (Sasson, 1997).
While finally no micro-organism fulfilled its promise of cheap protein, spirulina continued to give rise to3
3 GENERAL CHARACTERISTICS OF SPIRULINA
3.1 Morphology and taxonomy
3.1.1 Morphology
Spirulina is symbiotic, multicellular and filamentous blue-green microalgae with symbiotic bacteria that
fix nitrogen from air. Spirulina can be rod- or disk-shaped. Their main photosynthetic pigment is
phycocyanin, which is blue in colour. These bacteria also contain chlorophyll a and carotenoids. Some
contain the pigment phycoythrin, giving the bacteria a red or pink colour. Spirulina are photosynthetic
and therefore autotrophic. Spirulina reproduce by binary fission.
The helical shape of the filaments (or trichomes) is characteristic of the genus and is maintained only in a
liquid environment or culture medium. The presence of gas-filled vacuoles in the cells, together with the
helical shape of the filaments, result in floating mats. The trichomes have a length of 50 to 500 μm and a
width of 3 to 4 μm. However, cyanobacteria have a cell wall similar to that of Gram-negative bacteria:
they contain peptidoglucan, a lysozyme-sensitive heteropolymer that confers shape and osmotic
protection to the cell, in addition to other material not sensitive to lysozyme. In the 1970s, sphaeroplasts,
produced by disintegration of their cell wall by enzymatic treatment, were isolated from Oscillatoria
formosa, Fremyella dipplosiphon, Plectonema calothricoides and Synecchoccus lividus, as well as from
Anabaena ambique and Anacystis nidulans. In the case of spirulina, protoplasts had been obtained by
several researchers. For example, Abo-Shady et al. (1992) succeeded in obtaining protoplasts of Spirulina
platensis with high efficiency by lysozyme treatment at the exponential phase of algal growth at 30 °C
under illumination with 1 450 lux/m2/second. The body surface of spirulina is smooth and without
covering so it easily digestible by simple enzymatic systems.
3.1.2 Taxonomy
In 1827, P.J. Turpin isolated spirulina from a freshwater sample (Ciferri, 1983). In 1844, Wittrock and
Nordstedt reported the presence near the city of Montevideo of a helical, septal and green-blue
microalgae named Spirulina jenneri f. platensis. But it was not until 1852 that the first taxonomic report
written by Stizenberger appeared. He gave this new genus the name Arthrospira based on the septa
presence, helical form and multicellular structure. Gomont confirmed Stizenberger’s studies in 1892. This
author attributed the aseptate form to the Spirulina genus, and the septal form to the Arthrospira genus.
Geitler in 1932, because of the common helical morphology, reunified the members of the two genera
under the designation Spirulina without considering the septum presence, only morphological similarity.
In 1989, these micro-organisms were separately classified into two genera Spirulina and Arthrospira; this
classification is currently accepted (Tomaselli, Palandri and Tredici, 1996; Sánchez et al., undated).
Arthrospira maxima and A. platensis are the most important species in this genus and among these existed
taxonomic differences in filaments, vacuoles and external cover or capsule regularity of each filament
(Tomaselli, 1997). The worldwide investigation on microalgae has been carried out under the name of
“spirulina”; this common designation between scientists and consumers has proved difficult to change.
The microalgae under discussion belongs to the genus Arthrospira, but it will probably be called Spirulina
for some time. For the purpose of this report we refer to both collectively as “spirulina”.
The systematic position of cyanobacteria has been a matter of discussion, as these photosynthetic
organisms were first considered algae. In 1962, a distinction between prokaryotes and eukaryotes was
clearly established. The main difference is based upon the presence of cell organelles enveloped by a
phospholipidic membrane in eukaryotes. Stanier and Van Neil (1962) incorporated green-blue algae into
the prokaryote kingdom and proposed to call these micro-organisms cyanobacteria. This designation was
accepted and first published in 1974 in the Bergey's Manual of Determinative Bacteriology (Guglielmi,
Rippka and Tandeau De Marsac, 1993).
3.2 Natural habitat, source and growth
Besides Lake Texcoco, the largest spirulina lakes are in Central Africa around Lakes Chad and Niger, and
in East Africa along the Great Rift Valley. Under normal water conditions, Spirulina may be one of many
algal species. Lakes Bodou and Rombou in Chad have a stable monoculture of spirulina dating back
centuries. It is also a major species in Kenya's lakes Nakuru and Elementeita and Ethiopia's lakes
Aranguadi and Kilotes. Spirulina thrives in alkaline lakes where it is difficult or impossible for other micro
research and increasing production, reflecting its perceived nutritional assets (Falquet, 2000).4
organisms to survive (Kebede and Ahlgren, 1966). In natural lakes, the limited supply of nutrients usually
regulates growth cycles. New nutrients come from either an upwelling from inside the waterbodies,
influxes of nutrients from rivers or from pollution. The algae population grows rapidly, reaches a
maximum density, and then dies off when nutrients are exhausted. A new seasonal cycle begins when
decomposed algae release their nutrients or when more nutrients flow into the lake.
Spirulina is found in soil, marshes, freshwater, brackish water, seawater and thermal springs. Alkaline,
saline water (>30 g/l) with high pH (8.5–11.0) favour good production of spirulina, especially where
there is a high level of solar radiation at altitude in the tropics. Spirulina platensis and Spirulina maxima
thrive in highly alkaline lakes of Africa and Mexico where the cyanobacteria population is practically
monospecific. The higher the pH and the conductivity of the water, the greater is the likely predominance
of Spirulina spp. This is the case in the lakes of the lakes of the Rift Valley of eastern Africa, where pH can
reach values close to 11 and sodium carbonate is abundant. Spirulina platensis was isolated from waters
containing from 85 to 270 g of salt per litre, and optimum growth occurred between 20 and 70 g of salt
per litre. A relatively high cytoplasmic pH (4.2 to 8.5) may account for the ability of this micro-organism
to utilize ammonia as a source of nitrogen at high alkaline pH values (Sasson, 1997).
Spirulina is, like most cyanobacteria, an obligate photoautotroph, i.e. it cannot grow in the dark on media
containing organic carbon compounds. It reduces carbon dioxide in the light and assimilates mainly
nitrates. The main assimilation product of spirulina photosynthesis is glycogen. Spirulina shows an
optimum growth between 35 and 37 °C under laboratory conditions. Outdoors, it seems that an increase
in temperature up to 39 °C for a few hours does not harm the blue-green alga, or its photosynthetic
ability. Thermophilic or thermotolerant strains of spirulina can be cultivated at temperatures between 35
and 40 °C. Such a property has the advantage of eliminating microbial mesophilic contaminants. The
minimum temperature at which growth of spirulina takes place is around 15 °C during the day. At night,
spirulina can tolerate relatively low temperatures. The resistance of spirulina to ultraviolet rays seems to
be rather high (Richmond, 1986).
3.3 Biochemical composition
The basic biochemical composition of spirulina can be summarized as follows:
Protein: Spirulina contains unusually high amounts of protein, between 55 and 70 percent by dry weight,
depending upon the source (Phang et al., 2000). It is a complete protein, containing all essential amino
acids, though with reduced amounts of methionine, cystine, and lysine, as compared to standard proteins
such as that from meat, eggs, or milk; it is, however, superior to all standard plant protein, such as that
from legumes.
Essential fatty acids: Spirulina has a high amount of polyunsaturated fatty acids (PUFAs), 1.5–2.0 percent
of 5–6 percent total lipid. In particular spirulina is rich in γ-linolenic acid (36 percent of total PUFAs), and
also provides γ-linolenic acid (ALA), linoleic acid (LA, 36 percent of total ), stearidonic acid (SDA),
eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA).
Vitamins: Spirulina contains vitamin B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B6 (pyridoxine), B9
(folic acid), B12 (cyanocobalamin), vitamin C, vitamin D and vitamin E.
Minerals: Spirulina is a rich source of potassium, and also contains calcium, chromium, copper, iron,
magnesium, manganese, phosphorus, selenium, sodium and zinc.
Photosynthetic pigments: Spirulina contains many pigments including chlorophyll a, xanthophyll, betacarotene,
echinenone, myxoxanthophyll, zeaxanthin, canthaxanthin, diatoxanthin, 3-hydroxyechinenone,
beta-cryptoxanthin, oscillaxanthin, plus the phycobiliproteins c-phycocyanin and allophycocyanin.
Detailed biochemical composition analyses have been conducted of spirulina grown either under
laboratory conditions, collected in natural condition or in mass culture system using different agroindustrial
waste effluent. This was found to vary in response to the salinity of the growing medium –
Vonshak et al. (1996) reported that salt-adapted cells had a modified biochemical composition with a
reduced protein and chlorophyll content, and increased carbohydrate content. However the following
provides a review of the literature on the broad composition of spirulina.5
3.3.1 Proximate composition
Spirulina has high quality protein content (59–65 percent), which is more than other commonly used
plant sources such as dry soybeans (35 percent), peanuts (25 percent) or grains (8–10 percent). A special
value of spirulina is that it is readily digested due to the absence of cellulose in its cell walls (as it is the
case for eukaryotic green microalgae such as Chlorella, Ankistrodesmus, Selenastrum, Scenedesmus):
after 18 hours more than 85 percent of its protein is digested and assimilated (Sasson, 1997). The
composition of commercial spirulina powder is 60 percent protein, 20 percent carbohydrate, 5 percent
fats, 7 percent minerals, and 3–6 percent moisture, making it a low-fat, low calorie, cholesterol-free
source of protein.
Table 1: Various proximate analysis results of spirulina (% dry matter)
Component FOI, France SAC,
Thailand
IPGSR,
Malaysia
BAU,
Bangladesh
Crude protein 65 55–70 61 60
Soluble carbohydrate 19 14
Crude lipid 4 5–7 6 7
Crude fiber 3 5–7
Ash 3 3–6 9 11
Moisture 4–6 6 9
Nitrogen free extract (NFE) 15–20 4 17
FOI = French Oil Institute; SAC = Siam Algae Co. Ltd; IPGSR = Institute of Post-graduate Studies and Research laboratory,
University of Malaya; BAU = Bangladesh Agricultural University
3.3.2 Amino acids
Spirulina protein has a balanced composition of amino acids, with concentrations of methionine,
tryptophan and other amino acids almost similar to those of casein although this depends upon the
culture media used.
Table 2: Amino acid composition of spirulina (g/100 g)
Source
Lysine
Phenylalanine
Tyrosine
Leucine
Methionine
Glutamic acid
Aspartic acid
Tryptophan
Cystine
Siam
Algae
Co. Ltd.,
Thailand
2.60–3.30 2.60–3.30 2.60–3.30 5.90–6.50 1.30–2.00 7.30–9.50 5.20–6.00 1.00–1.60 0.50–0.70
IPGSR,
Malaysia
4.63±0.07 4.10±0.08 3.42±0.10 8.37±0.13 2.75±0.05 7.04±0.14 5.37±0.11 1.98±0.05 0.6±0.03
Table 2: Continued
Source
Serine
Arginine
Histidine
Threonine
Proline
Valine
Isoleucine7
when cells exhibited the higher polysaccharide content. In the case of Cr VI, the highest gmax exhibited
by cells cultivated in Zarrouk medium and showing the higher protein content (at pH 2.0). But pH did not
affect the adsorption of Pb II in the range of 3 to 5.5, nor of Cd in the range of 4 to 7. For Cr II, adsorption
observed only at a pH equal to 2.0 or lower.
3.3.5 Chelating of toxic minerals (neutralization of toxic minerals)
Spirulina has a unique quality to detoxify (neutralize) or to chelate toxic minerals, a characteristic that is
not yet confirmed in any other microalgae (Maeda and Sakaguchi, 1990; Okamura and Aoyama, 1994).
Spirulina can be used to detoxify arsenic from water and food. It also may be used to chelatize or detoxify
the poisonous effect of heavy metals (minerals) from water, food and environment. Beijing University has
extracted bioactive molecules from spirulina which could neutralize or detoxify the toxic and poisonous
effect of heavy metals, and which showed anti-tumor activity. Several institutions in China are focusing on
biomolecules which show anti-tumor, anti-age and anti-radiation properties (Liu, Guo and Ruan, 1991; Li
and Qi, 1997).
3.3.6 β-carotene and vitamins
The β-carotene, B-group vitamin, vitamin E, iron, potassium and chlorophyll available in the spirulina can
promote the metabolism of carbohydrate, fats, protein, alcohol, and the reproduction of skin, muscle and
mucosa. Spirulina contains large amounts of natural β-carotene and this β-carotene is converted into
vitamin A. According to the findings of the National Cancer Institute, United States of America, an intake
of 6.0 mg β-carotene daily may be effective in minimizing the risk of cancer. If anybody takes 4.0 g
spirulina daily, that is sufficient to get 6 mg β-carotene. At the same time, sufficient amount of B-group
vitamins, iron and calcium will be obtained. However, these nutrients obtained from 4.0 g of spirulina are
equivalent to or more than those obtained by eating more than 100 g of terrestrial bright-coloured
vegetables.
Alanine
Glycine
IPGSR,
Malaysia
3.84±0.06 4.94±0.07 2.81±0.06 3.35±0.06 4.11±0.05 4.02±0.06 3.85±0.10 10.81±0.14 6.66±0.10
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