Metabolism of D-lactate and structurally related organic acids in Chlamydomonas reinhardtii

Thesis/Dissertation · Tue Dec 31 23:00:00 EST 1985

OSTI ID:6549778

Husic, D W

During the initial minutes of anaerobiosis, /sup 14/C-labeled D-lactate, derived from the photosynthetic sugar phosphate pool, accumulated in the unicellular green alga, Chlamydomonas reinhardtii. The production of the D-isomer of lactate by algae is in contrast to plant and mammalian cells in which L-lactate is formed. After initial lactate formation, Chlamydomonas exhibits a mixed-acid type fermentation, thereby avoiding lactate accumulation and enabling the cells to tolerate extended periods of anaerobiosis. A pyruvate reductase which catalyzes the formation of D-lactate in Chlamydomonas was partially purified and characterized. Lactate produced anaerobically was metabolized only when Chlamydomonas cells were returned to aerobic conditions, and reoxidation of the D-lactate was apparently catalyzed by a mitochondrial membrane-bound dehydrogenase, rather than by the soluble pyruvate reductase. Mutants of Chlamydomonas, deficient in mitochondrial respiration, were used to demonstrate that lactate metabolism was linked to the mitochondrial electron transport chain. In addition, the oxidation of glycolate, a structural analog of lactate, was also linked to mitochondrial electron transport in vivo.

• Research Organization: Michigan State Univ., East Lansing (USA)
• OSTI ID: 6549778
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AEROBIC CONDITIONS
ALGAE
CARBON 14 COMPOUNDS
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHLAMYDOMONAS
ENZYMES
FRACTIONATION
GLYCOLIC ACID
HYDROXY ACIDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LACTATES
MEMBRANES
METABOLISM
MICROORGANISMS
MITOCHONDRIA
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
OXIDOREDUCTASES
PLANTS
SEPARATION PROCESSES
TRACER TECHNIQUES
UNICELLULAR ALGAE