Pellets formation in Aspergillus niger MYA 135: rol of hyphal morphology and conidia adhesion

PERA, LICIA MARÍA; COLÍN, VERÓNICA; ROMERO, CINTIA MARIANA; BAIGORI, MARIO DOMINGO

Tucumán

Congreso; SAIB 45 th Annual meeting; 2009

Argentine Society for Biochemistry and Molecular Biology Research

The morphology of filamentous fungi in submerged culture affects the broth rheology and in this turn may affect product yield. Thus, results of quantification of A niger MYA135 conidia adhesion capacity during the first hours of cultivation and its relationship with pellets formation were described. Modifications in the environmental conditions were tested by changing either the incubation temperature, the initial pH or by the addition of either CaCl2 or FeCl3 to medium. Conidia adhesion was quantify in polystirene microtiter plates by using sulforhodamine B staining. The adhesion unit was defined as the amount of adherent substance that produces an increase in absorbance at 570 nm of 0.01 per min per ml of culture. The hyphal growth unit length (lHGU ) was calculated by dividing the total hyphal length by the number of tips. This study suggested that conidia adhesion units per ml higher than 0.50 could be necessary to afford pellets formation. Thus, conidia showing 0.43 adhesion units per ml were followed by a dispersed mycelial growth. It was also observed that once the pellet was formed the lHGU had an important influence on its final diameter. Multiple linear regression with pellets diameters versus conidia adhesion (6h) and lHGU explains 82.6 % of the variability of the data (R2=0.826; R2(adj) =0.777; P=0.002).This work was supported by grants 693/04 CONICET and CIUNT 26/D409.