Rain Pluvialis Signal Substances

Astaxanthin, as a good colorant additive and a bioactive substance, has great commercial potential. The limited output of astaxanthin nowadays can meet the increasing demand worldwide. Therefore, much attention has been given to a unicellular green alga, Haematococcu pluvialis, in recent years due to its ability to accumulate large amount of astaxanthin. The possible effects of different traditional factors, like light (light regime and light intensity), temperature, nutrients (N, P, C, Fe, trace mental elements), vitamins, salinity and pH on the cell growth of this alga have been studied in number of laboratories and countries with a lot fruitful results. Unfortunately, the cell growth rate is still poor, the cell density of the culture is relatively low and the cell cycle is not well regulated. We suspected a new factor (auto-signals) maybe impress the cell growth of the motile cells, induce the cell transformation from the motile cells to the non-motile cells, and limit the scale up of culture this green alga. However, little is known about this interesting subject both in theory and in practice. Our aims of this thesis focus on above issue. Some positive progresses have been achieved thank to the financial supports from IFS (International Foundation for Sciences) and NSFC (National Nature Sciences foundation of China). The main results obtained are listed as below: 1. Auto-signals did exist in the old culture supematant and pay a significant inhibitory role in regulating cell cycle. The inhibitory effect of old culture supernatant would be easily detected especially in aerated culture and CO2 enriched aerated culture, but not in static culture. In the latter culture mode, other factors, such as inorganic carbon, cover up the inhibitory effect, which maybe the reason why this important inhibitory phenomenon has long been neglected in many eariy works. 2. The auto-signals in the old culture supematant would be extracted by ethyl acetate and dissolved in dimethyl sulphoxide. HC03, CO32 and other inorganic carbon were not connected with auto-signals although they really existed in the old culture supematant and affected the cell growth too. 3. Auto-signals were produced from Haematococcus itself and excreted into the culture medium because the production of auto-signals was culture-time dependent. No inhibitory effect was detected at the early culture stage. The longer the culture supernatant was treated by the alga, the more the auto-signals accumulated in the culture supernatant, and the heavier the cell growth was inhibited. This maybe the right reason why H. pluvia is would be easily cultivated for long. 4. The accumulation of auto-signals was connects with cell density too. More signals were produced in the high cell density culture. Therefore, auto-signals became one of the factors serious blocking cell growth in high even ultra-high culture of H. pluvialis, and need pay much attention to study deeply. 5. Auto-signals were mainly produced by the motile cells of H. pluvial is. When the motile cells transfonned into the non-motile cells, no evident showed a further increase of auto-signals in the old culture supernatant. 6. Although the mechanism of the auto-signals regulating the cell cycle has not clear yet, we still concluded a decrease in the motile cell parallel with a increase in the non-motile cell when H. pluvialis exposed to old culture supernatant or its crude extracts. Therefore, we sugges...