Updated project metadata. We studied the microbial community-based degradation of keratin, a recalcitrant biological material, by four well-characterized synergistic soil isolates, which have previously been shown to display synergistic interactions during biofilm formation; Stenotrophomonas rhizophila, Xanthomonas retroflexus, Microbacterium oxydans and Paenibacillus amylolyticus. We observed enhanced keratin weight loss in cultures with X. retroflexus, both in dual and four-species co-cultures, as compared to expected keratin degradation by X. retroflexus alone. To unravel the degradation shotgun-proteomics was performed on the secretome of all culture types including X. retroflexus.