鱼腥藻7120中异形胞发育的影响因子

以鱼腥藻7120为对象，考察了碳源浓度和种类、氮源浓度和种类、光强及NaCl浓度对鱼腥藻7120异形胞发育及发生频率的影响. 结果表明，NaNO3和NH4Cl都会抑制异形胞的分化，NaNO3对异形胞的抑制可以通过提高CO2浓度而解除，但NH4Cl的抑制作用是彻底的；而添加NaHCO3却不能在NO3-存在时诱导鱼腥藻产生异形胞；提高光强和NaCl浓度能够增加异形胞的比例. 证明了胞内碳氮比例的升高是异形胞分化的直接原因.

Factors Influencing the Heterocyst Differentiation in Anabaena sp. PCC7120

Anabaena sp. strain PCC7120 was a filamentous cyanobacterium that was capable of both oxygenic photosynthesis and aerobic nitrogen fixation. Heterocysts were developed from vegetative cells, which provided a suitable anaerobic environment for nitrogenase. The regulation of heterocyst development was influenced by several factors including concentrations, species of carbon and nitrogen sources, light intensity and NaCl concentration. In this paper, the effects of these factors on heterocyst differentiation in Anabaena sp. PCC7120 were studied. Results showed that NaNO3 and NH4Cl inhibited the development of heterocyst. But the elevated CO2 eliminated the inhibition of NaNO3 but not that of NH4Cl. The addition of NaHCO3 into the medium did not induce the production of heterocyst. Heterocyst frequency was enhanced by higher light intensity and NaCl concentration. It was found that heterocyst differentiation was induced in the presence of NaNO3 by elevated CO2, which was different from the opinion that Anabaena sp. strain PCC 7120 contained only vegetative cells in the presence of NaNO3.