Fermentative metabolism of Chlamydomonas reinhardtii

Journal Article · Tue May 01 00:00:00 EDT 1984 · Plant Physiol.; (United States)

OSTI ID:6137017

Gfeller, R P; Gibbs, M

The anaerobic starch breakdown into end-products in the green alga Chlamydomonas reinhardtii F-60 has been investigated in the dark and in the light. The effects of 3-(3,4-dicholorophenyl)-1,1-dimethylurea (DCMU) and carbonyl cyanide-p-trifluoromethoxyphenyl hydrazone (FCCP) on the fermentation in the light have also been investigated. Anaerobic starch breakdown rate (13.1 +/- 3.5 micromoles C per milligram chlorophyll per hour) is increased 2-fold by FCCP in the dark. Light (100 watts per square meter) decreases up to 4-fold the dark rate, an inhibition reversed by FCCP. In the dark, formate, acetate, and ethanol are formed in the ratios of 2.07:1.07:0.91, and account for roughly 100% of the C from the starch. H/sub 2/ production is 0.43 mole per mole glucose in the starch. Glycerol, D-lactate, and CO/sub 2/ have been detected in minor amounts. In the light, with DCMU and FCCP present, acetate is produced in a 1:1 ratio to formate, and H/sub 2/ evolution is 2.13 moles per mole glucose. When FCCP only is present, acetate production is lower, and CO/sub 2/ and H/sub 2/ evolutions is 1.60 and 4.73 moles per mole glucose, respectively. When DCMU alone is present, CO/sub 2/ and H/sub 2/ photoevolution is higher than in the dark. Without DCMU, CO/sub 2/ and H/sub 2/ evolution is about 100% higher than in its presence. In both conditions, acetate is not formed. In all conditions in the light, ethanol is a minor product. Formate production is least affected by light. The stoichiometry in the dark indicates that starch is degraded via the glycolytic pathway, and pyruvate is broken down into acetyl-CoA and formate. Acetyl-CoA is further dissimilated into acetate and ethanol. In the light, acetate is produced only in the presence of FCCP and, when photophosphorylation is possible, it is used in unidentified reactions. Ethanol formation is inhibited by the light in all conditions. 30 references, 5 figures, 2 tables.

• Research Organization: Brandeis Univ., Waltham, MA
• DOE Contract Number: AC02-76ER03231
• OSTI ID: 6137017
• Journal Information: Plant Physiol.; (United States), Vol. 75:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CHLAMYDOMONAS
METABOLISM
STARCH
ACETATES
BIOCHEMISTRY
BIOLOGICAL PATHWAYS
DAILY VARIATIONS
ETHANOL
FERMENTATION
FORMATES
ORGANIC COMPOUNDS
STOICHIOMETRY
VISIBLE RADIATION
ALCOHOLS
ALGAE
BIOCONVERSION
CARBOHYDRATES
CARBOXYLIC ACID SALTS
CHEMISTRY
ELECTROMAGNETIC RADIATION
HYDROXY COMPOUNDS
MICROORGANISMS
PLANTS
POLYSACCHARIDES
RADIATIONS
REAGENTS
SACCHARIDES
UNICELLULAR ALGAE
VARIATIONS
550500* - Metabolism