2.4. Inoculum
Aspergillus niger spores for inoculum were produced in 50 ml of Czapek Dox medium in a 250 ml Erlenmeyer flask and incubated at 28 C for 8 days. A spore suspension was prepared by adding 50 ml distilled water with Tween 80 (2%) and was stored at 4 C for a maximum of 3 weeks. The suspension contained 1010 spores/ml.