4A.3 Nannochloropsis oceanica growth optimization study: nitrogen source and concentration

Friday, 13 November 2009: 10:55 AM
Symone Johnson, Center of Marine Biotechnology, Baltimore, MD; and R. Cluster

Nitrogen is one of the principle elements for plant growth. It can be delivered in different forms. By comparing three different salts which contain nitrogen as nutrients and changing the concentration of these salts, certain optimal growth conditions of the microalgae Nannochloropsis oceanica were determined. The three salts used in this study were Potassium nitrate, Ammonium sulfate and Urea. All of these sources have been shown to support microalgal growth. Urea and Ammonium sulfate both support rapid cell growth with significant changes in original protocol. Using Urea as a nitrogen salt requires a lack of autoclaving which can introduce contaminants into a culture. Using Ammonium sulfate involves raising the salinity, which increases production cost. Potassium nitrate promotes algal growth utilizing original protocol but is the most expensive of the three salts. The concentration normally used in COMB algae culture, 4000 micromol/L, appears to be the best possible option. Anything under this concentration, 2000 micromol/L in this study, does not promote cell division and anything over, 8000 micromol/L in this study, is a waste of chemicals and, therefore, a waste of money. The main goal of high density algal culture is to grow the maximum amount of algae for the least amount of money. The results of this study help to show exactly which salt, and in what concentration, will promote optimal cell growth while being aware of cost.
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