title: A pilot-scale floating closed culture system for the multicellular cyanobacteriumArthrospira platensisNIES-39.
abstract: Microalgae are considered to be efficient bio-resources for biofuels and bio-based chemicals because they generally have high productivity. The filamentous cyanobacteriumArthrospira(Spirulina)platensishas been widely used for food, feed, and nutrient supplements and is usually cultivated in open ponds. In order to extend the surface area for growing this alga, we designed a pilot-scale floating closed culture system for cultivatingA. platensison open water and compared the growth and quality of the alga harvested at both subtropical and temperate regions. The biomass productivity ofA. platensisNIES-39 was ca. 9 g dry biomass m-2day-1in summer at Awaji Island (warm temperature region) and ca. 10 and 6 g dry biomass m-2day-1in autumn and winter, respectively, at Ishigaki Island, (subtropical region) in Japan. If seawater can be used for culture media, culture cost can be reduced; therefore, we examined the influence of seawater salt concentrations on the growth ofA. platensisNIES-39. Growth rates ofA. platensisNIES-39 in diluted seawater with enrichment of 2.5 g L-1NaNO3, 0.01 g L-1FeSO4·7H2O, and 0.08 g L-1Na2EDTA were considerably lower than SOT medium, but the biomass productivity (dry weight) was comparable to SOT medium. This is explained by the heavier cell weight of the alga grown in modified seawater media compared to the alga grown in SOT medium. Furthermore,A. platensisgrown in modified seawater-based medium exhibited self-flocculation and had more loosely coiled trichomes.
authors.affiliation: Kobe University Research Center for Inland Seas Rokkodai, Nadaku, Kobe, 657-8501 Japan ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 3-5 Sanbancho, Chiyodaku, Tokyo, 102-0075 Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Toyoshima
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nadaku, Kobe, 657-8501 Japan ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 3-5 Sanbancho, Chiyodaku, Tokyo, 102-0075 Japan.
authors.forename: Shimpei
authors.initials: S
authors.lastname: Aikawa
authors.affiliation: Kobe University Research Center for Inland Seas Rokkodai, Nadaku, Kobe, 657-8501 Japan ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 3-5 Sanbancho, Chiyodaku, Tokyo, 102-0075 Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamagishi
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nadaku, Kobe, 657-8501 Japan ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 3-5 Sanbancho, Chiyodaku, Tokyo, 102-0075 Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
authors.affiliation: Kobe University Research Center for Inland Seas Rokkodai, Nadaku, Kobe, 657-8501 Japan ; Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 3-5 Sanbancho, Chiyodaku, Tokyo, 102-0075 Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawai
keywords: Arthrospira (Spirulina) platensis NIES-39; Biomass productivity; Floating closed culture system; Modified seawater medium; Outdoor culture