Estudio de ácidos grasos y peroxidación lipídica en Euglena gracilis en condiciones de estrés

ROCCHETTA, I., MAZZUCA, M., BALZARETTI, V., CONFORTI, V. AND RÍOS DE MOLINA, M.C.

Buenos Aires

Congreso; VI Reunión Anual de SETAC Latinoamérica; 2003

Sociedad de Toxicología y Química Ambiental

The effect of hexavalent chromium was evaluated on the fatty acid content in two strains of Euglena gracilis, MAT (isolated from a highly polluted river, Matanza River) and UTEX 753 (from the Culture Collection of Algae of Texas University). Both strains were grown in autotrophic (Cramer and Myers medium) and photoheterotrophic (Buetow medium) conditions, using acetate like carbon exogenous source for the last one. The cells were exposed to different metal concentrations closed to the IC50 for 96 hours. The amount of polyunsaturated fatty acids (PUFAs) was the most affected, specially w6 (20:4; 18:2) and w3 (18:3). An important decrease was observed using the highest chromium concentration for the cells cultured in both mineral media. Hexavalent chromium had no effect on the total content of the mono-unsaturated fatty acids which were constant for all conditions. The saturated fatty acids showed an important increase only in treated cells growth in Buetow medium. In this culture medium the cells showed an  increase in the saturated fatty acids (14:0; 16:0).  This could be possible, to counteract the plyunsaturated fatty acid related with a repair/defence mechanism. PUFAs mentioned before, are correlated directly with the presence of chloroplasts, which are widely damaged by chromium. No differences were observed in both metal treated strains in the same culture conditions.  Autotrophic or photoheterotrophic conditions determined the major differences between fatty acid contents in both control and treated cells.