Original Papers

Archives of Microbiology

, Volume 140, Issue 2, pp 101-106

First online:

Botryococcus braunii carbon/nitrogen metabolism as affected by ammonia addition

  • Masayuki OhmoriAffiliated withLaboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California
  • , Fred R. WolfAffiliated withLaboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California
  • , James A. BasshamAffiliated withLaboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California

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Abstract

Carbon metabolism in photosynthesizing and respiring cells of Botryococcus braunii was radically changed by the presence of 1 mM NH4Cl in the medium, when the so-called “resting state” previously had been subjected to a nitrogen-deficient medium. Ammonia addition to the algae photosynthesizing with 14C-labelled HCO 3 - almost completely inhibited the synthesis of 14C-labelled botryococcenes and other hexane-extractable compounds, and also inhibited the formation of insoluble compounds; however, it resulted in a large increase in the synthesis of alanine, glutamine, other amino acids, and especially of 5-aminolevulinic acid. Total CO2 fixation decreased about 60% and O2 evolution decreased more than 50%.

CO2 fixation in the dark with ammonia present led to labelled products derived from phosphoenolpyruvate carboxylation, such as glutamine, glutamate, and malate. Respiratory uptake of O2 increased by about 70%.

The inhibition of terpenoid synthesis and increased synthesis of C5 amino acids by Botryococcus upon ammonia addition indicates 1) a diversion of acetyl coenzyme A from synthetic pathways leading to terpenoids and 2) increased operation of pathways leading to the synthesis of amino acids, especially 5-aminolevulinic acid, a precursor to chlorophyll biosynthesis.

Key words

5-aminolevulinic acid Ammonia botryococcus braunii Botryococcenes Carbon Hydrocarbon Metabolism Nitrogen Resting state Terpenoids