An integrated strategy for the effective production of bristle protein hydrolysate by the keratinolytic filamentous bacterium Amycolatopsis keratiniphila D2. (15th April 2019)

• Record Type: Journal Article
• Authors: Falco, Francesco Cristino; Espersen, Roall; Svensson, Birte; Gernaey, Krist V.; Eliasson Lantz, Anna
• Is Part Of: Waste management. Volume 89(2019)
• Page Start: 94
• Page End: 102
• Publication Date: 2019-04-15
• Subjects: Pretreated pig bristle -- Amycolatopsis keratiniphila -- Two-stage bioprocess -- Keratin biodegradation -- Keratinolytic protease -- Bristle protein hydrolysate; PBM porcine bristle meal -- BPH bristle protein hydrolysate -- SEC size-exclusion chromatography -- BCAAs branched-chain amino acids; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2019.03.067
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: A. keratiniphila D2 directed the consolidate bioprocessing of pretreated pig bristles. A novel two-stage biological degradation process was developed. Fed-batch enzymatic hydrolysis was carried out at high solids loading (16% w/v). About 73% of the protein material was recovered through a single unit operation. The obtained bristle protein hydrolysate showed a 95% in vitro pepsin digestibility. Abstract: In a conventional microorganism-mediated biological process for degradation of keratinous waste material the production of keratin-specific proteases (i.e., keratinases) and the hydrolysis of keratin-rich residual biomass both take place during the same stage of the bioprocess and, as a consequence, occur simultaneously under suboptimal conditions. In the present study the keratinolytic actinomycete Amycolatopsis keratiniphila D2 was successfully employed to biodegrade thermally pretreated porcine bristles at high solids loading (16% w/v) via a novel cultivation methodology. Indeed, the two-stage submerged fermentation process developed in this work enabled to efficiently recover, in a single unit operation, about 73% of the protein material contained in the keratinous biowaste structure, resulting in an overall accumulation of 89.3 g·L −1 protein-rich hydrolysate and a productivity of 427 mg crude soluble proteins per litre per hour. The obtained protein hydrolysate powder displayed a 2.2-fold increase in its in vitro pepsin digestibility (95%) with respect to the non-hydrolysed pretreated substrate (43%). In addition, the chromatogram obtained by size-exclusion chromatography analysis of the final product indicated that, among the identified fractions, those consisting of small peptides and free amino acids were the most abundantly present inside the analysed sample. Given these facts it is possible to conclude that the soluble proteins, peptides and free amino acids recovered through the newly designed two-stage bioextraction process could represent a viable alternative source of protein in animal feed formulation.