The Effect Of Different Concentration Of Salinity, Nitrogen And Phosphorous On The Growth And Metabolism Of Porphyridium Cruentum

In this paper, the effects of different contcentration of salinity, nitrate and phosphate on the growth and metabolism of Porphyridium cruentum were studied.The results indicated that Porphyridium cruentum could even normally grow under the high salinity of 70 and the cell density could reach 7.089×10⁶/mL, but the optimal salinity for cell growth was 20³0, at which the maximum beginning growth rate and the maximum cell density in the stationary phase were 1.004d^-1 and 8.641 ×10⁶/mL respectively;low salinity was favorable for the accumulation of chlorophyll a, dissoluble polysaccharides and dissoluble proteins, whereas the influence of the salinity to chlorophyll a of the unit cell was insignificant, moreover the contents of dissoluble polysaccharides and dissoluble proteins of the unit cell were higher in low salinity groups;the uptake of phosphate was irrelevant with salinity, but the utilization rate of nitrate increased with salinity.NaNO₃ had a little effect on the growth of Porphyridium cruentum comparatively, there were no distinct differences to the growth rate when the concentration of NaNO₃ was between 0.4¹.2g/L, but the increase of NaNO₃ could obviously prolong the logarithmic growth phase and increase the final biomass;KH₂PO₄ affected the growth of Porphyridium cruentum distinctly, which showed short growth period and poor initial growth state when concentration of KH₂PO₄ was lower than 0.015g/L and higher than 0.03g/L respectively;while NaNO₃ and KH2PO4 had little effect on accumulation of dissolvable polysaccharides, the content of NO₃^-, H₂PO₄^-(especially H₂PO₄^-) affected the synthesis of chlorophyll a and intracellular proteins significantly.The fastest beginning growth rate appeared in the contion of N/P=80, but the predominance of N/P=160 in the following phase was obvious, which provided with faster growth rate and higher final cell density;high N/P was more advantageous to the accumulation of energy in the cell;the suitable N/P for Porphyridium cruentum was about 120, which was far higher than the general optimal N/P standard of 16.