The Utilization of Acetate by Wild-type and Mutant Chlamydomonas dysosmos

SUMMARY: Chlamydomonas dysosmos is capable of normal photosynthetic growth, and of heterotrophic growth in darkness on acetate, pyruvate or lactate. An ultraviolet-induced mutant (D. 2075) was isolated which behaved like an obligate photo-autotroph. In the presence of 2:4-dinitrophenol (5 × 10−5 m) or sodium azide (1 × 10-5 m), the wild-type organism similarly behaved in growth experiments like an obligate photo-autotroph. Mutant cells oxidized all added acetate to CO2. Wild-type cells oxidized a portion of the substrate, and utilized some of the energy so released for the assimilation of the remainder. There are indications that in the wild type the assimilation of acetate commences only after a period of acetate oxidation. The mutant is believed to be impaired in its ability to effect oxidative assimilation.