Studying Carbon and Energy Metabolism in Autotrophic and Heterotrophic Chlorella Cells

CORREGIDO, MC; PIATTONI, CV; IGLESIAS, AA

Mar del Plata

Congreso; LI Reunión Anual de SAIB; 2015

SAIB

In plants, photosynthetic (or autotrophic) and non photosynthetic (or heterotrophic) cells have different carbon and energy fluxes, being photosynthates produced by autotrophic cells and providing carbon and energy to heterotrophic cells. Instead, some unicellular green algae can growth as photosynthetic or heterotrophic (also mixotrophic) cells according to the culture conditions. Chlorella sp, is a particular example, since it is able to produce and accumulate varying proportions of lipids (predominantly heterotrophic) and/or starch (mainly photosynthetic) according to the growing conditions. The metabolic changes produced in each kind of cells are not completely understood. To study the dynamics of carbon partitioning in Chlorella sp. we grew the cells in two different media: BOLD3N and M16, auto- and hetero-trophic, respectively. The resulting cells showed different protein profiles by 2D-electrophoresis. Differential expression of specific proteins was also detected by western blot analysis. We determined the activity of enzymes involved in key steps of carbon metabolism and found important differences in cells accumulating starch or lipids. The ability of Chlorella to modify its metabolism and change the type of carbon reserve constitutes a useful system to understand carbon partitioning in cells accumulating lipids and/or starch, a subject that is critical in biotechnology.