TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Components: The co-concentrating fatty acids do not comprise juniperonic acid (JPA) and/or sciadonic acid. The biomass is a microalgal biomass. The microalgal biomass is a Nitzschia laevis biomass. The diatoms comprise Nitzschia species, preferably N.laevis. Preferred Method: The microorganisms are cultured in a culture medium under non-limiting nitrogen and non-limiting phosphate provision. The method (M1) further involves extracting fatty acids from the biomass to yield a fatty acid composition. The method (M1) further involves enriching the fatty acid composition in EPA or purifying EPA from the fatty acid composition to yield an enriched or purified fatty acid composition. The EPA in the fatty acid mixture forms at least 5% of total fatty acids. The diatoms are cultured in heterotrophic culture in a fermenter. The method (M2) involves culturing the diatoms by continuous fermentation. The culturing process is carried out at 12-35 degrees C, and at pH of 7-8.7. The method (M3) involves adding fresh nutrient solution having a molar ratio of available carbon to nitrogen of 1-30 to the fermenter during the culturing process. The method (M3) involves harvesting the diatoms at a rate as the average number of diatoms in the fermenter remains constant over time when the harvested volume is replaced with fresh nutrient solution having a molar ratio of available carbon to nitrogen of 1-30. The conditions in method (M4) include a mutagenic agent, an agent selective for increased EPA productivity, or an agent selective for decreased ARA productivity. Preferred Composition: The level of EPA in the fatty acid composition is at least 5 wt.% of the total fatty acids in the composition. The level of EPA in the enriched or purified fatty acid composition is at least 30 wt.% of the fatty acids in the composition. The carbon source comprises glucose.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The source of bioavailable silicon is in the form of silicate. The concentration of silicate does not fall below 150 mu M. The silicate is in the form of sodium or potassium metasilicate. The nutrient solution comprises phosphorus in the form of phosphate. The molar ratio of organic carbon to phosphorus in the form of phosphate is not greater than 1250:1. The molar ratio of carbon to silicon in the form of silicate source is 100:1-850:1. The nutrient solution comprises phosphorus in the form of phosphate. The molar ratio of carbon to phosphorus in the form of phosphate is 100:1-1250:1.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The carbon source is chosen from glucose, hydrolyzed starch or hydrolyzed whey. The nitrogen source is in the form of sodium nitrate or potassium nitrate. The nitrogen sources are supplemented with an amino acid source. The amino acid source is chosen from corn steep liquor, yeast extract, tryptone, peptones, lysine and glutamate. ACTIVITY - Cardiovascular-Gen; Anorectic; Antidiabetic; Cytostatic; Immunosuppressive; Hypotensive. No biological data given.    MECHANISM OF ACTION - None given.    EXAMPLE - No suitable example given.