Botryococcus braunii carbon/nitrogen metabolism as affected by ammonia addition

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 HCO3-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%.