| Iodine is one of necessary trace elements to human bodies. But inorganic iodine can't be well absorbed by bodies and even produces toxicity. Iodine will have wide edible valuation only when it is transformed into organic iodine . This research chose Spirulina maxima (Setch. et Gard.) Geitler, an important health and therapeutic food, to transform inorganic iodine into organic one by cultivation of Spirulina in inorganic iodide-enriched culture medium, in order to produce iodine-rich Spirulina which has potential value in food, medicine and additive fields.The experimential results showed that different kinds of iodides could affect the growth and iodine content in cells of Spirulina maxima differently. Under 0-200mg/L iodide concentration, KI promoted the growth of Spirulina maxima much more significantly than KIO4 and NaIO4. KIO4 and NaIO4 began to inhibit the cell growth under relatively lower level of concentration (50mg/L). It is suggested that iodine content in algal cells depend on the sorts and concentration of iodide added into cultrue medium. KI, compared with KIO4 and NaIO4, was an optimal iodide for accumulation of iodide in Spirulina maxima cells and its appropriate concentration for culture of iodine-rich Spirulina maxima was 4000mg/L. Under this concentration, the dry weight harvest of Spirulina in experimental group (225mg/L) was as about 1.1 times as the control (241mg/L). Algal cells resulted in highest accumulation rate of iodine that the total iodine content in experimental group (0.1777%dw) was as about 4.8 times as the control (0.0372%dw). Inorganic iodine content of experimental group (0.0597%dw) was about 7.1 times as the control (0.0084%dw) and organic iodine (0.1180%dw) was as about 4.2 times as the control (0.0288%dw).The organic iodine accounted for 66.4% of total iodine content in cells of Spirulina which was mainly combined to protein (41.2%). Percentage in lipid and hydrocarbon was 10.1% and 14.7% respectively.Iodide-enriched culture (4000mg/L KI) has also resulted in the higher percent of organic biochemical compounds in cells of Spiurlina. The protein,total saccharide and amino acid was 74.1 l%dw, 25.46%dw and 76.93%dw respectively, which was respectively 1.40, 1.06 and 1.39 times of those of controls (52.77%dw, 24.07%dw and 55.32%dw). It was suggested that KI-enriched culture of Spirulina could not only promote the growth of algal cells and raise the total iodine content, but also raise the contents of protein, saccharide and amino acid in algal cells.The single factor test of various cultivating conditions on growth and accumulation of iodine of Spirulina maxima showed that the single factor under which accumulating rule of iodine reached highest was as follow: nitrogen concentration 2.5g NaNO^L, phosphorus concentration 0.0195g KH2PO4/L, pH 8.98, temperature 28癈 and illumination 23001ux white light. The normal test showed that the optimal combinations of cultivating conditions for high harvest of algal cells and iodine content were pH=9.0, N/P=30/1 and 28 癈.Using algal light reactor (volume SOL) to cultivate Spirulina maxima has resulted in higher production of algal cells in dry-weight (801.1mg/L), which was as 1.10 times as that cultivated in common flask under the same conditions (729.2mg/L), and the total iodine content of former (0.2202%dw) was slightly higher (1.06 times ) than the latter (0.2077%dw). These suggested that using light-reactor to cultivate iodine-rich Spirulina maxima could not only raise its production , but also improve its quality.Iodide-enriched cultivation of Spirulina maxima in 103L pool showed that adding KI could promote the dry weight production of algal cells (the first and second batch of culture were 276.53mg/L and 139.26mg/L respectively), which were as about 3 times as the control (119.83mg/L and 53.10mg/L respectively). The total iodine content of the experimental groups (0.101%dw and 0.093%dw respectively) were both higher than the control (0.080%dw and 0.071%dw respectively). Organic iodine in Spirulina maxima cells was... |
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