Isolation And Biological Characteristics Of Mutant Of Dunaliella Salina Synthesizing Zeaxanthin

A high Zeaxanthin producing mutant (Zea1) of Dunaliella salina was obtained as the subject through mutagenesis by UV and NTG. This paper systematically studied the influence of intensity of illumination, NaCl, carbon source, nitrogen source, phosphate source to the the growth and Zeaxanthin accumulation of Zea1; four cultivate methods----traditional batch method, fractional adding, complete replacement and incomplete replacement were compared with the influence to the growth and Zeaxanthin accumulation of Zea1.The effect of defferent intensity of illumination on the cell number and Zeaxanthin accumulation of wild type and Zea1 as parameters were compared. The results showed that under the same illumination condition, cell number and Zeaxanthin accumulationn of Zea1 were a little higher than wild type. Hight light intensity was obviously in favour of cell growth and Zeaxanthin accumulation of Zea1, the cell number was as 1.29 and 7.08 times as those of normal light intensity and low light intensity, and the Zeaxanthin content was as 1.4 and 4.56 times as those of normal light intensity and low light intensity. Aged medium was against the growth and Zeaxanthin accumulation of Zea1, while Centrifugating and changing with fresh medium every other day was propitious to the growth and Zeaxanthin accumulation of Zea1. Especially at day 12, the cell number and the Zeaxanthin content in Zea1 were as 3.02 and 12.6 times as the control sample. The best concentration of NaCl for the the growth of Zea1was 0.75mol/L, and the best concentration of NaCl for the the Zeaxanthin accumulation was 1mol/L. Compared to the sucrose and NaHCO₃, glucose was best for the growth and Zeaxanthin accumulation of Zea1. Among three different nitrogen source, 1mmol/L of KNO₃ was the optimum concentration for the growth of Zea1, and 1mmol/L (NH₄)₂SO₄ was propitious to Zeaxanthin accumulation. To sum up the whole condition, 1mmol/L(NH₄)₂SO₄ was the best. 0.1 mmol/L KH₂PO₄ was the optimum to the growth and Zeaxanthin accumulation of Zea1.The quadric regression equation for the cell number and Zeaxanthin content of Zea1 to the concentration of glucose,(NH₄)₂SO₄ and KH₂PO₄ were established from the response surface methodology experiment. All the arguments showed significant efects to the cell number and Zeaxanthin content and the empirical method was reliable. The effect on the response value of three factor of C, N, P source to the cell number and Zeaxanthin content were reflected from the response surface methodology graph. Compared to yileld that the effect on the two response values of N source (x₂) was the most significant, P source (x₃) was less, C source was least. The optimization of labor organization of cell growth and Zeaxanthin accumulation of Zea1 was 12.33mmol/L glucose, 0.94mmol/L (NH₄)₂SO₄, 0.23mmol/L KH₂PO₄, the relative error between actual value and predicstive value were 2.27% and 2.8%, lower than 5%. The results showed the parameter from the response surface methodology experiment were accurate and reliable.Four cultivate methods, traditional batch method, fractional adding, complete replacement and incomplete replacement, were compared with the cell number and Zeaxanthin accumulationn as parameters of Zea1. The data showed that complete replacement method was beneficial to cell growth and Zeaxanthin accumulationn of Zea1.The survival rate of D. salina cells was decreased significantly by UV radiation in the period of 0⁶0s. After adding Dashi, in the same radiation time, the survival rate of D. salina cells was no difference compared to the control sample, under the UV radiation, the effect on the Dashi protection to the strian was not obvious. The survival rate of D. salina cells was decreased significantly by NTG mutagenesis in the period 0s²5min, After adding Dashi, in the same radiation time, the survival rate of D. salina declined more rapidly compared to the control sample, under the mutagenesis by NTG, the effect on the Dashi protection to the strian was obvious.