PHOTO-ORGANOTROPHIC GROWTH OF EUGLENA-GRACILIS Z ON GLYCOLATE

1. Euglena gracilis Z cultured photo-organotrophically, under normal atmosphere and continuous light, in mineral medium supplemented with 25 mM glycolate as the sole carbon source was able to metabolize this substrate. 2. Final productivities (weights per ml) of proteins, lipids and paramylum were twice as abundant in glycolate medium as in mineral medium. 3. The generation time, which was not dependent upon glycolate (25 or 50 mM), was reduced by an increased illumination. Incorporations of NaH 14CO3 and [l-14C]glycolate had shown that: (i) a small amount of photorespiratory CO2 participated in paramylum synthesis and (ii) important decarboxylations from glyoxylate and glycine took place. 4. The ultrastructural characteristics of Euglena gracilis grown with glycolate resembled those of photo-autotrophic cells. 5. We demonstrated that in such cells it was the RuBP carboxylase which had the preponderant role and not the PEP carboxylase which on the other hand was remarkably active in cells grown with lactate source.