OPTIMIZATION OF SOLID-STATE FERMENTATION PARAMETERS FOR THE PRODUCTION OF XYLANASE BY TRICHODERMA-LONGIBRACHIATUM ON WHEAT BRAN

Solid-state fermentation has the potential to produce inexpensive enzy mes for use in high-volume industrial applications. Process parameters such as substrate moisture content and length of fermentation can hav e a significant effect on the amount and timing of enzyme production. This study was conducted in two stages, a screening stage and an optim ization stage, to determine the effects of moisture content of the sub strate, surfactant addition upon inoculation depth of the substrate, a nd duration of fermentation on xylanase activity produced by Trichoder ma longibrachiatum. Screening fermentations were conducted at 25 degre es C, 50 and 75% wet basis moisture content (w.b.), 0.0 and 0.2% v/v s urfactant addition, 0.5 and 1.5 cm depth of wheat bran, and 5 and 10 d ays of fermentation. Optimization fermentations were conducted at 25 d egrees C, 45, 55, and 65% moisture content (w.b.), 1.0, 1.5, and 2.0 c m depth of wheat bran, and three and five days of fermentation. Experi ments were conducted as full factorial experiments with three replicat ions of each treatment. The optimal values of the process variables we re selected based on the units of xylanase activity produced per gram of wheat bran (U/g). Moisture content, depth of substrate, and duratio n of fermentation had significant main effects on the production of en zyme activity. Surfactant addition upon inoculation had interaction ef fects with moisture content, and the duration of fermentation by moist ure content interaction also was significant. The treatment of 55% moi sture content, 1.5 cm depth of substrate, and five days of fermentatio n resulted in the highest average xylanase activity (716 U/g wheat bra n).