Design of Fermentative Technology for the Valorization of Pig Bristle Keratins into Biostimulant for Agricultural Applications

The elimination of keratin-derived waste, such as pig bristles, represents a significant challenge due to its high production levels and resistance to degradation. However, the keratinous composition also makes pig bristles a valuable waste material with significant potential for bioconversion into biostimulants rich in bioavailable nitrogen, peptides, and amino acids. To achieve degradation, microorganisms with keratinolytic activity isolated from the raw material were selected. Based on the best performance in plant PGP traits, solubility, and protease activity, <i>Sporosarcina luteola</i> was chosen to implement a fermentation technology that converts pig bristle waste. The fermented product comprises three classes of biostimulant components: the biomass of <i>S. luteola</i>, the enzymatic secretions of this microorganism, and the hydrolyzed organic matter from pig bristles, which is rich in protein hydrolysates and free amino acids. The biostimulant was evaluated in soil at the biochemical level (enzymatic activities) and in plants under oxidative stress, demonstrating a positive effect. These findings highlight the fermentation process using <i>S. luteola</i> as a promising strategy for the comprehensive valorization of pig bristle waste, resulting in products with significant agronomic and environmental benefits.