. Initial conidia adhesión of Aspergillus niger and its role in pellets formation.

COLÍN, VERÓNICA; BAIGORI, MARIO DOMINGO; PERA, LICIA MARÍA

Rosario. Santa Fe, Argentina.

Congreso; SAIB 42 th Annual Meeting.; 2006

SAIB

Initial conidia adhesion of Aspergillus niger and its role in pellets formation   Colin V, Baigorí MD and Pera LM   PROIMI-CONICET Av. Belgrano y Pje. Caseros, 4000 Tucumán, Tel: 03814344888, e-mail: lymb@arnet.com.ar   Introduction: Environmental conditions markedly influence the growth pattern of filamentous fungi, which can range from a pelleted to a dispersed filamentous form, influencing in this way both the growth rate and the product formation. Although pellets formation is primarily due to conidia agglomeration, the involved mechanism has not been clearly elucidated. The aims of this work were to quantify the initial conidia adhesion under different environmental conditions and to establish its role in pellets formation. Methods: Assays of conidia adhesion were done in 96-well polystyrene microtiter plates by using sulforhodamine B staining to quantify the adherent conidia. 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 effect of modifications in the environmental conditions was tested by changing either the temperature of incubation or the initial pH of the medium as well as by the addition of either CaCl2 or FeCl3. Results and conclusions: Differential adhesion degree in response to environmental conditions was detected. Under our experimental condition, initial adhesion units lower than 0.4 obtained either at initial pH 2 or in presence of 1 g/l FeCl3 were not compatible with pellets formation. This work was supported by grants 693/04 CONICET and PICTO 761