Ogbonna J C, Ichige E, Tanaka H
Institute of Applied Biochemistry, University of Tsukuba, Tsukuba City, Ibaraki, Japan.
Appl Microbiol Biotechnol. 2002 Mar;58(4):532-8. doi: 10.1007/s00253-001-0901-8. Epub 2002 Jan 24.
Interactions between photoautotrophic and heterotrophic metabolism in photoheterotrophic culture of Euglena gracilis were studied. Under a low light supply coefficient, these two metabolic activities seem to proceed independently. The cell growth rate in photoheterotrophic culture was about the sum of the growth rates in pure photoautotrophic and heterotrophic cultures. However under a high light supply coefficient, both photoautotrophic and heterotrophic (glucose assimilation) metabolic activities were inhibited, resulting in a low photoheterotrophic growth rate. The photoheterotrophic culture was more sensitive to photoinhibition compared to the pure photoautotrophic culture. Inhibition of glucose assimilation in the photoheterotrophic culture was due to both direct and indirect (through photosynthesis) effects of high light intensity. Cell growth, glucose assimilation and alpha-tocopherol content of the cells were higher when ambient air was used for aeration than when a mixture of carbon dioxide and air was used. Even when photosynthesis was inhibited by addition of 3-(3,4-dichlorophenyl)- 1,1-dimethylurea to photoheterotrophic culture, light stimulated alpha-tocopherol synthesis by E. gracilis.
研究了纤细裸藻光异养培养中光合自养代谢与异养代谢之间的相互作用。在低光照供应系数下，这两种代谢活动似乎独立进行。光异养培养中的细胞生长速率约为纯光合自养培养和异养培养中生长速率之和。然而，在高光照供应系数下，光合自养和异养（葡萄糖同化）代谢活动均受到抑制，导致光异养生长速率较低。与纯光合自养培养相比，光异养培养对光抑制更敏感。光异养培养中葡萄糖同化的抑制是由于高光强度的直接和间接（通过光合作用）效应。当使用环境空气曝气时，细胞的生长、葡萄糖同化和α-生育酚含量高于使用二氧化碳和空气混合物时。即使通过向光异养培养中添加3-（3,4-二氯苯基）-1,1-二甲基脲抑制光合作用，光仍能刺激纤细裸藻合成α-生育酚。
