光照-温度交互作用及不同氮源对拟柱孢藻生长的影响

Effects of Temperature-irradiance Interactions and Three Nitrogen Sources on Growth of Cylindrospermopsis raciborskii

摘要:

为探讨不同环境因子对拟柱孢藻（Cylindrospermopsis raciborskii）生长的影响，对从广东省镇海水库分离的2株拟柱孢藻在不同的温度和光照组合，及不同氮源条件下的生长进行了研究。结果表明，在3种光强下，拟柱孢藻N1和N8藻株的生长随温度的上升而增加，均在28℃高光强下达到最大比生长速率，而N8藻株对低温的适应能力要高于N1藻株。拟柱孢藻N1和N8在各硝态氮浓度下均能正常生长，但仅能在中低浓度的铵态氮和尿素氮中生长，高浓度（128~247 mg L^-1）的铵态氮和尿素氮会显著抑制藻细胞生长；在3种氮源下，N1藻株的比生长速率均显著大于N8藻株，这说明N1藻株对不同氮源的利用能力要高于N8藻株。因此，广东省的拟柱孢藻具株系多样性，喜好高温，适应较宽的光照范围，并可利用多种氮源用于生长，这可能是该地区拟柱孢藻水华频发的原因。

Abstract:

In order to evaluate the effects of critical environmental factors on growth of Cylindrospermopsis raciborskii, the growth of two strains isolated from Zhenhai Reservoir in Guangdong Province was studied under combining temperature from 12℃ to 32℃ and irradiance (from 30 to 120 µmol m^-2s^-1) and three nitrogen sources (nitrate-N, ammonium-N and urea-N). The result showed that the growth of N1 and N8 strains of C. raciborskii increased with temperature under three light conditions and their growth rate was the biggest at 28℃ with high irradiance. Cylindrospermopsis raciborskii N1 strain was not able to grow at both 12℃ and 16℃, while N8 strain only could not be at 12℃. These suggested that the strain N8 had higher tolerance to low temperature than N1. The strains N1 and N8 grew well under nitrate-N (2-247 mg L^-1), but only at a low level of ammonium-N and urea-N. Moreover, the growth of both strains completely inhibited under high ammonium-N and urea-N (128-247 mg L^-1). The specific growth rates of N1 strain under three nitrogen sources were always higher than those of N8 strain, which indicated that the capability for strain N1 to utilize nitrogen was stronger than strain N8. In conclusion, Cylindrospermopsis raciborskii isolated from Guangdong Province has high strain diversity and adapt to high temperatures and a wide range of light intensities, and is able to use multisource of nitrogen. This may be the reason for frequent occurrence of C. raciborskii in the studied region.