Feather is the main waste of poultry industries and constitutes of 90% keratin. Wastes composed of keratin are insoluble and recalcitrant to degradation using conventional decomposing methods. Microbial degradation for keratinous wastes is a promising approach for being eco-friendly and economically. However, due to insolubility of keratinous waste, it has several challenges in upstream and downstream processes such as culture medium optimization, designing of bioreactor, bioreaction/flow type, bioreactor configurations considering mass and heat transfer limitations, rheology derived problems, monitoring of microbial activity, choosing of the right scale-up parameter and purification. In this study, the challenges for keratin degradation processes were discussed with the aim of opening new opportunities for keratinous waste treatments in industrial level.
Keywords: Bioreactor configurations; Insoluble protein; Keratin; Upstream processes.