Influence of metal ions on pellet morphology and polygalacturonase synthesis by Aspergillus niger 3T5B8

Sônia Couri, Gustavo Adolfo Saavedra Pinto, Lilian Ferreira de Senna, Hebe Labarthe Martelli
2003 Brazilian Journal of Microbiology  
The effects of cations addition on pellet morphology and polygalacturonase (PG) synthesis by Aspergillus niger 3T5B8 were studied and compared with a control system. Fe(II), Cu(II), Zn(II) and Mn(II) were added to the fermentation medium separately, and also as combined groups of cations. The addition of Fe 2+ and/or Zn 2+ ions was significantly positive to the enzyme production. A positive effect in the biomass content, however, was only obtained when the same metal ions were added separately.
more » ... e added separately. On the other hand, Cu 2+ and Mn 2+ ions had almost no effect on these parameters. The morphology of the pellets was studied by image processing techniques. Small pellets with small cores were usually obtained when Fe 2+ and Zn 2+ ions were individually or collectively added to the medium. The pellets produced in media containing Fe 2+ or Zn 2+ ions were compact, while the ones produced in a medium containing both cations were considered diffuse. Autolysis of the core was observed for large control pellets, due to the deficient nutrient transfer to the interior of the pellet. The pellets obtained in a medium containing both Fe 2+ and Zn 2+ ions were high enzyme producers, probably due to a loose morphology, induced by the presence of combined groups of metal ions in the medium, favoring the nutrient transfer.
doi:10.1590/s1517-83822003000100005 fatcat:u3ukrlh44nczxkj7ksgsz5z6ee