Synergism between ultrasonic pretreatment and white rot fungal enzymes on biodegradation of wheat chaff

•Ultrasonic pretreatment combined with lignolytic enzyme enhanced biodegradation of wheat chaff.•Increased amounts of sugar- and phenolic-derived components were generated as evidenced of degradation.•The pretreatment approach enhanced the in vitro rumen digestibility of the solid residues.

Lignocellulosic biomass samples (wheat chaff) were pretreated by ultrasound (US) (40 kHz/0.5 W cm−2/10 min and 400 kHz/0.5 W cm−2/10 min applied sequentially) prior to digestion by enzyme extracts obtained from fermentation of the biomass with white rot fungi (Phanerochaete chrysosporium or Trametes sp.). The accessibility of the cellulosic components in wheat chaff was increased, as demonstrated by the increased concentration of sugars produced by exposure to the ultrasound treatment prior to enzyme addition. Pretreatment with ultrasound increased the concentration of lignin degradation products (guaiacol and syringol) obtained from wheat chaff after enzyme addition. In vitro digestibility of wheat chaff was also enhanced by the ultrasonics pretreatment in combination with treatment with enzyme extracts. Degradation was enhanced with the use of a mixture of the enzyme extracts compared to that for a single enzyme extract.