Ultrasounds pretreatment of olive pomace to improve xylanase and cellulase production by solid-state fermentation

Abstract

Olive mills generate a large amount of waste that can be revaluated. This work aim to improve the production lignocellulolytic enzymes by solid-state fermentation using ultrasounds pretreated olive mill wastes. The composition of olive mill wastes (crude and exhausted olive pomace) was compared and several physicochemical characteristics were significantly different. The use of both wastes in SSF was evaluated and a screening of fungi for xylanase and cellulase production was carried out. After screening, the use of exhausted olive pomace and Aspergillus niger led to the highest enzyme activities, so that they were used in the study of ultrasounds pre-treatment. The results showed that the sonication led to a 3-fold increase of xylanase activity and a decrease of cellulase activity. Moreover, the liquid fraction obtained from ultrasounds treatment was used to adjust the moisture of solid and a positive effect on xylanase (3.6-fold increase) and cellulase (1.2-fold increase) production was obtained.

Mediterranean agro‐industrial wastes as valuable substrates for lignocellulolytic enzymes and protein production by solid‐state fermentation

“…The goal was the selection of fungus that produces higher cellulose and xylanase activities and increases the protein content of agro‐industrial wastes. In previous work, these strains showed potential for producing lignocellulolytic enzymes on agar plates. In addition, A. uvarum MUM 08.01 showed good results in the increase of protein of agro‐food wastes mixtures …”

“…Ashes were determined by high temperature treatment at 575 °C for 2 h in a muffle furnace. C and minerals were analysed following the process described by Salgado and co‐workers Table shows the initial composition of solid wastes.…”

Lipase production by solid‐state fermentation of olive pomace in tray‐type and pressurized bioreactors

“…The composition of substrates before and after SSF was determined to evaluate the increase of nutritional quality and potential applicability for animal feed. Initial characterization of OP was performed by Leite et al . and is presented in Table .…”

“…and is presented in Table . Characteristics of WB and of fermented substrate (SSF OP + WB), such as MC, total solids, ash, lignin, hemicellulose, cellulose, lipids, protein concentration, reducing sugars, phenols, nitrogen, carbon, crude protein, minerals and heavy metals, were determined according to Leite et al . and Salgado et al …”

“…The composition of substrates before and after SSF was determined to evaluate the increase of nutritional quality and potential applicability for animal feed. Initial characterization of OP was performed by Leite et al 31 and is presented in Table 1. Characteristics of WB and of fermented substrate (SSF OP + WB), such as MC, total solids, ash, lignin, hemicellulose, cellulose, lipids, protein concentration, reducing sugars, phenols, nitrogen, carbon, crude protein, minerals and heavy metals, were determined according to Leite et al 31 and Salgado et al 25 The extracts for antioxidant determination in unfermented and fermented substrates were obtained by methanol extraction with liquid:solid ratio of 20:1 (v/w).…”