Inorganic carbon acquisition by Chlamydomonas acidophila across a pH range
Inorganic carbon acquisition by Chlamydomonas acidophila across a pH range
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嗜酸衣藻在 pH 范围内获取无机碳
作者：
E. Spijkerman
嗜酸衣原体Negoro有一个较高的最大增长率通气时，5%CO2（v/v）比在非通气条件下，在外部pH值高于2。在pH为1.0或2.0的培养基中，观察到的最大生长速率下降CO2通气后，与nonaerated条件相比。在非常低和非常高的外部pH条件下，都检测到外部碳酸酐酶的诱导;这在CO2通气细胞中比在非通气细胞中更加明显。因此，这表明碳酸酐酶的诱导是嗜酸衣原体应激反应的一部分。在pH 2.65和pH 6.0下驯化的嗜酸衣原体的一些生理特性的比较表明，CO2通气增加总的最大光合作用在两个pH值，而呼吸，光驯化，和光抑制没有受到影响。在pH 2.65时，嗜酸衣藻在非通气条件下具有碳浓缩机制，而在pH 6的CO2通气条件下则没有。在O-2生产中使用的CO2的亲和力是不依赖于CO2曝气，但它是在pH值为6比它是在pH值为2.65低得多。CO2动力学特征表明，自然环境中嗜酸衣原体的光合作用不受无机碳的限制
Chlamydomonas acidophila Negoro had a higher maximum growth rate upon aeration with 5% CO2 (v/v) than in nonaerated conditions at an external pH above 2. In medium with a pH of 1.0 or 2.0, a decrease in the maximum growth rate was observed upon CO2 aeration in comparison with nonaerated conditions. At both very low and very high external pH conditions, an induction of external carbonic anhydrase was detected; this being more pronounced in CO2-aerated cells than in nonaerated cells. It is therefore suggested that the induction of carbonic anhydrase is part of a stress response in Chlamydomonas acidophila. Comparison of some physiological characteristics of Chlamydomonas acidophila acclimated at pH 2.65 and at pH 6.0, revealed that CO2 aeration increased gross maximum photosynthesis at both pHs, whereas respiration, light acclimation, and photoinhibition were not effected. At pH 2.65, Chlamydomonas acidophila was found to have a carbon-concentrating mechanism under nonaerated conditions, whereas it did not under CO2-aerated conditions at pH 6. The affinity for CO2 use in O-2 production was not dependent on CO2 aeration, but it was much lower at pH 6 than it was at pH 2.65. CO2 kinetic characteristics indicate that the photosynthesis of Chlamydomonas acidophila in its natural environment is not limited by inorganic carbon