title: Growth promotion of Spirulina by steelmaking slag: application of solubility diagram to understand its mechanism.
abstract: A solubility diagram was employed to understand growth promotion of Arthrospira (Spirulina) platensis by steelmaking slag (SMS). The growth promotion effect of 112 % of freshwater microalga A. platensis was obtained using 5 g/L SMS. However, metabolites, such as pigments, and protein content of A. platensis were not significantly affected. Several metals dissolved in Spirulina-Ogawa-Terui medium were detected by inductively coupled plasma atomic emission spectrometry just after the addition of SMS. The solubility diagram provides information on the chemical speciation of metal elements based on pH and concentration. It is a useful tool to understand the effect of metals on microalgal growth. The metal elements used to control microalgal growth are essential minerals but also act as a source of oxidative stress. Regarding the affecting mechanism of SMS, iron may be the primary element regulating microalgal growth via pathway involving reactive oxygen species, as revealed by superoxide dismutase assay.
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Fukuoka, 808-0196, Japan.
authors.forename: Reijiro
authors.initials: R
authors.lastname: Nogami
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Fukuoka, 808-0196, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Nishida
authors.affiliation: Department of Algal Biotechnology, Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Rd, Cau Giay Dist, Hanoi, Vietnam.
authors.forename: Dang Diem
authors.initials: DD
authors.lastname: Hong
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Fukuoka, 808-0196, Japan. wakisaka@life.kyutech.ac.jp.
authors.forename: Minato
authors.initials: M
authors.lastname: Wakisaka
keywords: Growth promotion; Oxidative stress; Solubility diagram; Spirulina; Steelmaking slag