STUDIES ON THE PRODUCTION OF USEFUL CHEMICALS, ESPECIALLY FATTY-ACIDSIN THE MARINE DIATOM NITZSCHIA-CONSPICUA GRUNOW

A local marine diatom, Nitzschia conspicua Grunow, was cultured in enr iched synthetic seawater using flasks (agitated by magnetic stirring) and a 1.2 1 fermenter. Lipids, fatty acids, proteins, carbohydrates an d ash of the flask cultures were determined at various stages of growt h (day 3, 5, 7, 10, 13, 15 and 17). The fermenter culture was harveste d during the stationary phase for similar chemical analyses. N. conspi cua attained a higher biomass concentration during the stationary phas e when cultured in the fermenter (188 mg dry weight l-1) than in flask s (140-151 mg dry weight l-1). However, both systems showed similar sp ecific growth rates based on chlorophyll-a concentration. Appreciable amounts of the essential fatty acids 20:4 (0.6-4.7% total fatty acids) and 20:5 (1.9-4.7% total fatty acids) are present in this diatom. Max imal amounts of these fatty acids were produced after 7 days' growth ( i.e. 2 days after the end of the exponential phase). Lipids, fatty aci ds, proteins, carbohydrates and ash varied with culture age in N. cons picua.