A sterile syringe was used to collect samples via the sampling tube driven to the very bottom of the fermentor. Prior to sample withdrawal, 3 mL of culture broth was taken and discharged in order to wash the remains away from the sampling tube. When taking the sample a few mil­liliters of fermentation broth was taken aseptically from the vessel and with the exception of an aliquot used for optical density (OD) measurement, the sample was immediately subjected to phase separation (4000 rpm, 10 min). The supernatant collected was assayed for reducing sugar content, glucose concentration, and cellulase activity.

Optical Density

OD was read at 660 nm (OD660) against distilled water (14).

Determination of Reducing Sugar Content

Total reducing sugar was determined by the dinitrosalicylic acid (DNS) method (15) using D-glucose as a standard. Appropriately diluted samples were made up to 1.5 mL with distilled water, and 3 mL of DNS reagent was added. The color obtained after boiling the mixture for 5 min and then diluting with 16 mL of distilled water was evaluated by reading the absorbance at 550 nm. Total reducing sugar generated during the assay was estimated as glucose equivalents.