RESUMO

Alginate production by Azotobacter vinelandii in chemostat cultures was evaluated at different dilution rates (D) and inlet sucrose concentrations of 5 and 20 g l(-1). At the low inlet sucrose concentration, the molecular weight of alginate increased from 800 to 1800 kDa when D increased from 0.05 to 0.10 h(-1), whereas the opposite trend was observed with the high inlet sucrose concentration. This behaviour can be explained by changes in specific sucrose uptake rate. Thus, a decrease in alginate molecular weight was dependent on the specific sucrose uptake rate when this rate was higher than 0.42 g g(-1) h(-1). The manipulation of the D can be used to select the molecular weight of alginate in continuous culture.

Assuntos

Alginatos/química , Azotobacter vinelandii/citologia , Azotobacter vinelandii/metabolismo , Técnicas de Cultura de Células/métodos , Biomassa , Ácido Glucurônico/biossíntese , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Peso Molecular , Sacarose/metabolismo