Protopectinase production in solid state culture ofAspergillus awamori

Summary Protopectinases (PPases) are a heterogeneous group of enzymes that release water soluble pectin from insoluble protopectin in plant tissues by restricted degradation of the substrate. In all cases reported to date, PPases of bacterial or yeast origin were produced in liquid culture. Here, we describe the growth and PPase production ofAspergillus awamori IFO 4033 in solid state culture. Petri dishes containing 10 g of wheat bran and 15 ml of 0.2 M HCl were inoculated with 2 ml of a suspension with 1 × 10⁵ spores.ml⁻¹ and incubated for 48 h at 30°C. PPase activity on lemon (PPase-l) and apple (PPase-a) protopectins was maximum at 24 h of culture (1490 and 610 U.g⁻¹, respectively) and then decreased. Pectinase activity on lemon and apple pectin and polygalacturonase activity were maximum at 48 h. Hence, the crude enzyme pool obtained at 24 h of process was appropriate for extraction of citrus and apple pectin with a minor subsequent degradation of the solubilized pectin. The ratio of PPase-l to PPase-a changed during culture, so there seemed to be at least two PPases with different substrate specificity.