CONICET | Buscador de Institutos y Recursos Humanos

Occurrence of cyanobacterial blooms constitutes a major concern for human and livestock health and environment preservation. The model filamentous cyanonabcerium Anabaena variabilis reduces its doubling time from ca 30 h to 8 h when organic carbon is supplied to the culture medium, at the time that glycogen accumulation takes place. In this work we analyzed the effect of fructose on carbon metabolism in A. variabilis. We show that the nitrogen and carbon sources and light regulate the expression of the sucrose synthase (SuS, UDP-glucose: D-fructose 2-a-D-glucosyl transferase, EC 2.4.1.13) encoding gene (susA), in a similar way that they regulate the accumulation of polysaccharides. Furthermore, glycogen content in an Anabaena sp. mutant strain with an insertion inactivation of susA was lower than in the wild-type strain under diazotrophic conditions, while both glycogen and polysaccharides levels were higher in a mutant strain constitutively overexpressing susA. We also show that there are soluble and membrane-bound forms of SuS in Anabaena. Taken together, these results indicate that SuS is involved in the sucrose to polysaccharides conversion under fast-growing conditions induced by the availability of organic carbon, combined nitrogen and light. Supported by PICT Nº 21227-53, PIP 6105, UNMdP and FIBA.