Effect of variation of nitrogen and phosphorus concentrations in the zarrouk's medium for Spirulina sp. Culture
1992
Sumalee Dulaya-anukij
Laboratory cultures of Spirulina sp were on reducing nitrogen (NO3-N) and phosphorus (PO4-P) concentrations in the Zarrouk's medium separately. The set nitrogen levels were 2 %, 6 %, 12 %, 25 % and 50 % of the medium, and the set phosphorus levels were 1 %, 3 % and 25 % of the medium. Each experiment had a control and last for 5 days. Specific growth rate (from OD560), increasing of dry weight and chlorophyll per day were used to determine the growth conditions. The increasing of chlorophyll per day was used to indicate algal quality. The algae grew normally for 1, 2, 4, 5 and 5 days in the sequences of nitrogen levels respectively. In 1 % phosphorus level the algae had lower quality within 24 hrs; those in 3 % and 25 % phosphorus levels grew normally for 4 and 5 days respectively. The rates of nitrogen and phosphorus utilizations of the controls were in the ranges of 22.91-83.91 and 4.62-13.98 mg/l per 1 increasing of OD560 per day respectively. The nitrogen and phosphorus concentrations that made the algae lower the quality depended on the optical density and growth rate of the algae. The 12 % nitrogen and 3 % phosphorus levels were the lowest levels in this experiment that could grow algae until harvesting and decrease 18.1 % and 65.8 % of the nitrogen and phosphorus costs respectively and the nutrients had to be added every 4 days
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