Studying Carbon Metabolism in Phaeodactylum tricornutum

M.B. BOSCO, M. ALEANZI, V. MÁRQUEZ, A. BECCARIA, A.A. IGLESIAS

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual de SAIB; 2007

SAIB

EN-P21.S T U D Y I N G C A R B O N M E TA B O L I S M I NPHAEODACTYLUMTRICORNUTUMBosco MB,Aleanzi M, MárquezV, Beccaria A, Iglesias AA.Lab Enzimología Molecular, FBCB, UNL, Paraje ?El Pozo?, CC242, S300ZAASanta Fe. E-mail: mbbosco@fbcb.unl.edu.arPhaeodactylumtricornutumEscherichia coliDiatoms are key constituents of aquatic phytoplanktoncommunities. Their contribution to marine primary productivitywas estimated between 30-40%. They can grow auto-, hetero-, andmixotrophically. Because of its small genome (less than 30 Mb) andthe possibility of being routinely transformed,has emerged as a model species for dissecting diatombiology. Our interest is to characterize changes in enzymes levelsand properties associated with different growing conditions of thealgae. We optimized the diatom auto- and mixotrophic growthusing diverse substrates in batch mode. The highest biomassconcentration for mixotrophic growth was obtained using acidcasein hydrolysate (1.5 g/l) and glycerol (46.05 g/l) as nutrients.Distinct activities of enzymes involved in carbon metabolism wereassayed in extracts of the diatom samples. Also, the genes codingfor fructose1,6bisP aldolase (FBA), three glyceraldehyde3Pdehydrogenases, two P-glycerate kinases (PGK) and triosePisomerase were cloned. Expression of the genes inrendered the proteins in inclusion bodies, except for FBA andPGK1 that were obtained as soluble recombinant enzymes.Characterization of the kinetic, regulatory and structural propertiesof the enzymes is being helpful to better understand metabolicpathways and their regulation in the diatom.