混合氮源对扁藻与金藻共培养和单种培养生长的影响

Effects of mixed nitrogen sources on growth of mixed culture and monoculture of Platymonas subcordiformis and Isochrysis galbana

采用均匀设计,研究了硝酸钠(NO3-N)、尿素(NH2-N)和硫酸铵(NH4-N)3种氮源对亚心形扁藻(Platymonas subcordiformis)与球等鞭金藻(Isochrysis galbana)共培养和单种培养生长的影响。结果表明,不同氮源对扁藻与金藻在不同培养方式下的生长均存在显著差异(P<0.05)。共培养时,硝酸钠质量浓度对扁藻和金藻的总细胞密度(Yt)和最终细胞密度的体积比(Yr)没有影响,尿素质量浓度对Yt有正调节作用,而硫酸铵质量浓度对Yt有负调节作用、对Yr有正调节作用。当培养液中NH2-N质量浓度为21.01 mg/L,扁藻和金藻接种体积比(Xv)为14.15时,Yt最大(1 508.9×104个/mL);当NH4-N质量浓度、Xv分别为21.00 mg/L和14.15时,Yr最大,为87.46。单种培养金藻时,硝酸钠略优于尿素,2种氮源对其生长均有正调节作用,而硫酸铵起负调节作用。当培养液中加21.01 mg/L的NO3-N和NH2-N时,金藻的细胞密度达到最大值(862.6×104个/mL);不同氮源对扁藻生长的调节作用与金藻相反,当扁藻接种密度为4.6×104个/mL,培养液中NH4-N质量浓度为21.00mg/L时,扁藻细胞密度达到102.2×104个/mL,其值最大。

Uniform design was performed to examine effects of 3 mixed nitrogen sources on growths of mixed cultures and monocultures of Platymonas subcordiformis and Isochrysis galbana. The results showed the growth performances of P. subcordiformis and I. galbana in different treatments were significantly different （P〈0. 05）. In mixed culture, the experimental concentration of NaNO3 had no effects on total cell density （Yt） and volumetric ratio （Yr）, and the concentration of CO（NH2）2 had a positive influence upon Yt, but the concentration of （NH4）2SO4 resulted in a negative effect on Yt compared to the Yr, which was sharply increased. When the cell volmetric ratio （Xv） of inoculative P. subcordiformis to I. galbana was 14. 15 and each concentration of NH2-N and NH4-N was 21.01 mg/L, the optimum Yt and Yr got to 1 508.9×10^4 cell/ mL and 87.46, respectively. In monoculture of I. galbana, the nitrogen source of NaNO3 was slightly better than that of CO（NH2）2, and both all had positive effects on growth of I. galbana. On the contrary, nitrogen source of （NH4）2SO4 was of inverse influence on the algal growth. According to the optimum result, the maximal cell density of I. galbana was 862.6 × 10^4 cell/mL when concentrations of NO3-N and NH2-N were given at 21.01 mg/L each. Meanwhile, in monoculture of P. subcordiformis, the contrary conclusions were also drawn while enriched the same nitrogen sources and concentrations in the monoculture medium. If the inocula- tive cell density and concentration of NH4-N were 4.6 × 10^4 cell/mL and 21.01 mg/L, respectively, the top cell density of P. subcordiformis can be got theoretically, which was 102. 2×10^4 cell/mL.