Increase of protein content and production of lignocellulolytic enzymes by simultaneous solid-state fermentations of brewery, olive mill and winery wastes

Abstract

Frequently, the agro-industrial wastes are used as animal feed, however many times these wastes have a poor nutritional quality, mainly they have a low protein content and their digestibility is hard. These disadvantages can be avoided by solid-state fermentation (SSF) of the wastes by filamentous fungi. Winery, brewery and olive mill wastes were used as solid substrates for the production of lignocellulolytic enzymes and to increase the crude protein content of agro-industrial wastes. After selection of the fungus in previously study, it was performed an experimental design to evaluate the benefits of using mixtures of wastes in different proportions as solid substrate in SSF by A. ibericus. The optimum substrate was a mixture of brewery spent grain and vine-shoot trimmings which achieved and increase the protein content (16.3 %), xylanase (89.33 U/g), cellulose (3.46 U/g) and -glucosidase (21.91 U/g) activities. Through this study, it was possible to conclude that the SSF by A. ibericus is a suitable biotechnology process to increase the nutritional quality of agro-industrial wastes and to produce value-added products as enzymes in the same low-cost process.