Feather Waste Biorefinery using Chryseobacterium sp. A9.9 Adapted to Feathers as its Sole Carbon and Nitrogen Source

Abstract: Feathers represent a natural source of proteins packed in a highly stable structure. Because of their recalcitrance, feathers can take considerable time to naturally decompose. To help avoid their accumulation in the environment, feather waste needs to be sustainably handled, e.g., by converting them into more valuable products through microbial processes. Here, we screened bacteria from the rhizosphere of Mimosa pudica for their ability to degrade feathers and use them as their substrate. Three candidates produced proteases that were active in a wide range of temperature (30–70 °C) and pH (5–11). One of the isolates, identified as Chryseobacterium sp. A9.9, effectively degraded feathers, yielding 45% mass shrinkage in 24 h. Laboratory adaptation of Chryseobacterium sp. A9.9 using feathers as its sole carbon and nitrogen source for 30 passages improved its ability to degrade feathers and to produce proteases with higher activity, yielding higher total protein content. In addition, because Chryseobacterium sp. A9.9 produces flexirubin, a yellow pigment with potential biomedical applications, the system may add value to the bioconversion process. The use of microorganisms from local resources and simple methods to improve their performance to degrade recalcitrant wastes such as feathers provides an attractive approach to biomass valorization. Graphical Abstract: [Figure not available: see fulltext.]