The Mechanism For Response Of Phaeodactylum Tricornutum To Environmental Factors

Diatoms, which play a vital role in the biogeochemical cycle, are responsible for one-fifth of the primary productivity on Earth. This phylogenetically young group includes two major classes, the pennates and the centrics, and they are widespread in all kinds of aquatic environments. Phaeodactylum tricornutum Bohlin is the first pennate diatom for which the complete genome is known. It has three convertible morphotypes: oval, fusiform, and triradiate. Its outer shell is weakly silicified, and silicification is restricted to one valve of the oval cells. Silicon is not required for the growth of P. tricornutum under laboratory conditions. Besides, P. tricornutum is an important animal feed in aquaculture, and is rich in active substances such as EPA and fucoxanthin. Furthermore, it is a potential source of biodiesel fuel. Thus P. tricornutum not only has important important ecological status, but also has great economic value.The genomic and physiological studies on P. tricornutum has been a hot research field, however, information on proteome investigations of the organism was rarely reported. In this study, we mainly use proteomics techniques, combine with physiological and biochemical methods to explore the variation on different levels(proteome, transcriptome, and physiological) of P. tricornutum, when the algae faces different environmental factors such as nutrient deficiency and illumination change.It was found that photosynthesis and the Calvin cycle were down-regulated, while glycolysis, the TCA cycle and lipid biosynthesis were up-regulated under the condition of nitrogen starvation; silicon may be beneficial for P. tricornutum living in deeper water; and its major light-harvesting complex, the fucoxanthin–chlorophyll a/c proteins, changes when it moves to deeper water; iron cannot improve lipid production of P. tricornutum, but it promotes the Calvin cycle. The effect of all the four flocculants is significant, and Fe Cl3 is the best flocculants for harvesting P. tricornutum when the target product is fucoxanthin, as it in?uenced physiological activity of P. tricornutum the least and it did not lead to degradation of high value products.This study has great ecological significance, and provide guidance for the optimization of culture conditons of oil-producing microalgae. Besides, it provides experimental basis for “Bottleneck” problems of large-scale microalgae cultivation.