Otto Pulz

Increase of the Content of Polyunsaturated Fatty Acids in Porphyridium cruentum by Low-temperature Stress and Acetate Supply

The influence of a cold stress and the addition of the acetate, which plays an essential role in the intermediary metabolism, on the synthesis of long-chain polyunsaturated fatty acids in Porphyridium cruentum Rhodophyceae was investigated. The results obtained demonstrate that under temperature stress an increased synthesis of long-chain polyunsaturated fatty acids on a dry mass basis is achieved, whereas a decline was observed concerning the biomass yield. In contrast, the addition of acetate has a stimulating effect on fatty acid biosynthesis as well as on biomass production. A shift of the fatty acid spectrum in favour of higher unsaturated fatty acids was obtained only under temperature stress

The influence of low and high oxygen concentration on the yield and spectrum of fatty acids in Porphyridium cruentum

Summary The influence of O2-concentration on the growth rate of the red alga Porphyridium cruentum, on the fatty acid spectrum, as well as on the content of the individual fatty acids was subject of investigations. The O2-concentration was changed at different times of the batch cultivation. The influence of increased as well as of decreased O2-concentrations was investigated. It was evident that high oxygen concentration inhibited the biomass production. Nevertheless, this stress factor was connected with increasing EPA and AA contents as a short-time effect. This timely limited increase of EPA and AA was connected with a corresponding increase of the content of total fatty acids and at the expense of a decreasing content of palmitic acid. In the absence of oxygen the. biomass production increased and the content of most of the fatty acids decreased for a short period of 6 h. After an adaption period of 24 h the fatty acid content increased also in this case. The effect of O2-caused EPA increase is most evident if the oxygen concentration is increased on the 5th day of batch cultivation.

Increasing the Content of Polyunsaturated Fatty Acids in Spirulina Platensis and Porphyridium Cruentum by Variation of Light and Nutrients

The investigation of the influence of light on PUFA synthesis in microalgae has brought about a partly controversial pattern. Based on the GLA distribution in lipid fractions (mainly glycolipids) and on investigations of Sukenik et al. [2] who detected an increased MGDG and DGDG content at reduced light intensity, the following items were investigated: Influencing the GLA content of Spirulina platensis by additions of acetate, variation of light intensity and exposure to light, combination of acetate addition and light variation. Influencing the AA and EPA content of Porphyridium cruentum by variation of light intensity or exposure to light, with spec ia l attention to PUFA changes immed iate ly a f ter changed exposure to light.