7.3 Mass-Production of Microalgae
The single-celled green alga Chlorella has drawn attention as a food source because
of its high photosynthetic performance and protein content. Studies on its bulk
culturing have been carried out around the world since World War II. Established in
1957, the Japan Chlorella Research Institute has conducted research on bulk culturing that has led to the development the open and closed circulation methods that
today serve as the prototypes for bulk culturing of microalgae (Aaronson and
Dubinsky 1982).
Research on Chlorella production as a source of protein was halted after its costs
were found to be prohibitive in temperate climates such as Japan’s. Experiments
with the application of Chlorella algal bodies at the time, however, found physiological effects for both humans and animals, and their use for purposes other than
protein began drawing attention. Commercial Chlorella production began in 1964,
and the alga has been developed into a foodstuff with both nutritional and pharmacological potential (Pires 2015).
Commercial production of Chlorella is currently under way in countries such as
Japan, Taiwan, and Bulgarian. Most of the algal bodies produced are consumed as
health food. Applications span a diverse range of fields besides food, including
agriculture, marine products, and bioenergy. Because of the great diversity of microalgae, this section will first explain about the bulk culturing methods used for
Chlorella production, their characteristics, and current uses of Chlorella.
7.3.1 Chlorella Production
A. Bulk Culturing
(1) Forms of Culturing
Large-scale culturing of Chlorella may be classified into three types according to
the method used to supply carbon and energy sources: photoautotrophic culture,
which uses inorganic carbon to multiply through photosynthesis; mixotrophic
culture, which uses involves photosynthesis and use of organic as well as inorganic
carbon; and heterotrophic culture, which uses organic carbon (Liu and Hu 2013).
Photoautotrophic culture typically takes place in outdoor settings and has a yield
of roughly 2.0–23.3 g dry leaf bodies per square meter per day. In principle, the use
of solar energy should allow for the most economical production of leaf bodies.
Because the upper limit of production is determined by amount of sun exposure and
the process requires a large culturing area and large amounts of medium, however,
culturing temperatures cannot be adjusted in the winter, and productivity from
photoautotrophic culturing in a temperate region such as Korea is low. Moreover,
the process also requires a supply of carbon dioxide.
7.3 Mass-Production of Microalgae
205
The single-celled green alga Chlorella has drawn attention as a food source because
of its high photosynthetic performance and protein content. Studies on its bulk
culturing have been carried out around the world since World War II. Established in
1957, the Japan Chlorella Research Institute has conducted research on bulk culturing that has led to the development the open and closed circulation methods that
today serve as the prototypes for bulk culturing of microalgae (Aaronson and
Dubinsky 1982).
Research on Chlorella production as a source of protein was halted after its costs
were found to be prohibitive in temperate climates such as Japan’s. Experiments
with the application of Chlorella algal bodies at the time, however, found physiological effects for both humans and animals, and their use for purposes other than
protein began drawing attention. Commercial Chlorella production began in 1964,
and the alga has been developed into a foodstuff with both nutritional and pharmacological potential (Pires 2015).
Commercial production of Chlorella is currently under way in countries such as
Japan, Taiwan, and Bulgarian. Most of the algal bodies produced are consumed as
health food. Applications span a diverse range of fields besides food, including
agriculture, marine products, and bioenergy. Because of the great diversity of microalgae, this section will first explain about the bulk culturing methods used for
Chlorella production, their characteristics, and current uses of Chlorella.
7.3.1 Chlorella Production
A. Bulk Culturing
(1) Forms of Culturing
Large-scale culturing of Chlorella may be classified into three types according to
the method used to supply carbon and energy sources: photoautotrophic culture,
which uses inorganic carbon to multiply through photosynthesis; mixotrophic
culture, which uses involves photosynthesis and use of organic as well as inorganic
carbon; and heterotrophic culture, which uses organic carbon (Liu and Hu 2013).
Photoautotrophic culture typically takes place in outdoor settings and has a yield
of roughly 2.0–23.3 g dry leaf bodies per square meter per day. In principle, the use
of solar energy should allow for the most economical production of leaf bodies.
Because the upper limit of production is determined by amount of sun exposure and
the process requires a large culturing area and large amounts of medium, however,
culturing temperatures cannot be adjusted in the winter, and productivity from
photoautotrophic culturing in a temperate region such as Korea is low. Moreover,
the process also requires a supply of carbon dioxide.
7.3 Mass-Production of Microalgae
205