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Heterotrophic (Dark) CO 2 Fixation by Euglena gracilis. Possible regulation by tricarboxylic acid cycle intermediates
Author(s) -
PEAK J. G.,
PEAK M. J.
Publication year - 1976
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1976.tb05264.x
Subject(s) - euglena gracilis , citric acid cycle , tricarboxylic acid , carbon fixation , euglena , biochemistry , heterotroph , biology , metabolism , nitrogen fixation , bacteria , photosynthesis , gene , genetics , chloroplast
SYNOPSIS. Heterotrophic (dark) CO 2 fixation by Euglena gracilis strain Z varies with phase of batch culture and mode of nutrition. Dark CO 2 fixation increased transiently during the growth of cells under photoautotrophic (CO 2 , light) and heterotrophic (glucose, dark) conditions. Cells grown heterotrophically with acetate or ethanol had no transient increase in fixation. The addition of acetate to a heterotrophically growing culture during the period of increasing dark CO 2 fixation resulted in rapid elimination of this fixation. The results suggest that dark CO 2 fixation in Euglena functions in anaplerotic feeding of the tricarboxylic acid cycle, drained by biosyntheses during growth. Induction of the glyoxylate cycle by acetate may provide an alternate source of tricarboxylic cycle intermediates, obviating the requirement for dark CO 2 fixation as a source of the intermediates.