中文摘要：

采用液体悬浮培养方法研究了有机碳源对发状念珠藻（Nostoc flagelliforme）单体细胞生长及光合作用的影响。结果表明发状念珠藻单体细胞具有利用有机碳源进行混合营养生长的能力,葡萄糖和蔗糖对其生长具有明显的促进作用,乳糖、木糖、乙酸钠和甘油也能促进其生长。在BG-11培养基中添加浓度为3.98g·L^-1葡萄糖,培养7d,细胞生物量（干重）达到1.77g·L^-1,是同等培养条件下光合自养所得干重的4.81倍。通过测定添加有机碳源初时和生长2d后发状念珠藻单体细胞的光合放氧速率的变化情况,发现在培养初时,低光照强度（低于50μmol·m^-2s^-1）有机碳源不能促进藻细胞的光合作用;在光饱和点（100μmol·m^-2s^-1）混合营养藻细胞的净光合放氧速率达到192.31μmolO2·（mgChl）^-1·h^-1,是光合自养细胞的1.57倍。进入对数期后,混合营养藻细胞的净光合作用降低,但是呼吸速率达到703.43μmolO2·（mgChl）^-1·h^-1,是光合自养细胞的14.27倍;真正光合作用（净光合作用和呼吸作用之和）提高。

英文摘要：

The effects of organic sources on the growth and photosynthesis of Nostoc flagelliforme cells in liquid suspension culture were studied.The results show that the glucose and sucrose in the medium can promote the growth of N.flagelliforme cells efficiently;in addition,lactose,xylose,acetate and glycerol can also promote the growth of N.flagelliforme cells.It indicates that the N.flagelliforme cells have the ability of utilizing the organic carbon sources to grow mixotrophically.In the BG-11 medium with glucose concentration of 3.98 g·L^-1 and after 7 d of cultivation,the cell density of N.flagelliforme can reach 1.77 g·L^-1,which is 4.81 folds of that obtained under autophototrophic condition.Through the determination of the photosynthetic rate variation of N.flagelliforme cells at its beginning and after 2 d cultivation of mixotrophic growth,it was found that,at the initial time after addition of organic carbon sources,the maximum net photosynthetic rate of N.flagelliforme cells is low when the light intensity of illumination is low（lower than 50 μmol·m^-2·s^-1）.However,the net photosynthetic rate of N.flagelliforme cells in mixotrophic culture reaches 192.31μmolO2·（mgChl）^-1·h^-1 at light saturation point,which is 1.57 folds of that obtained under autophototrophic culture.After 2 d of cultivation,the net photosynthetic rate of N.flagelliforme cells in mixotrophic culture decreases,while their respiration rate increases to 703.43 μmolO2·（mgChl）^-1·h^-1,which is 14.27 folds of that in autophototrophic culture.Thus,the gross photosynthesis rate（net photosynthetic rate plus respiration rate） of N.flagelliforme cells increases.