Biomass production and nutrient uptake by Isochrysis aff. galbana (Clone T-ISO) cultured with a low cost alternative to the f/2 medium

Biomass production and uptake of nitrate, phosphate and ammonium were determined in batch culture of the marine microalgae Isochrysis aff. galbana (Clone T-ISO)for 7 days comparing an agricultural fertilizer media with the f/2 media. The average cellular density obtained with the f/2 media and the agricultural fertilizer showed no significant difference (P > 0.05) (average growth rate of 0.43 and 0.42 per day, respectively). During the first 4 days, the phosphate in the agricultural fertilizer media was consumed ten times faster than in the f/2 media. When nitrate and ammonium were added together, the ammonium was consumed eight times faster than the nitrate in a period of 5 days. Below concentrations of 1.36 mu M Of ammonium, nitrate began to be consumed. The nitrate uptake in the f/2 media increased substantially (to 555 mu M) from the fourth to the seventh day of culture. The cost of the f/2 media is eight times more expensive than that prepared with agricultural fertilizer. We conclude that agricultural fertilizer did not have a negative effect compared to f/2 on the growth rate of IT. aff. galbana (Clone T-ISO), produced the same amount of biomass as the f/2 media, and was much cheaper. The alternate media shows great potential for use in aquaculture for I. aff. galbnna (Clone T-ISO) production. (C) 1999 Elsevier Science B.V. All rights reserved.