Valorization of alkaline-enzymatic hydrolysates from sheep wool as bio-input-based technologies for Trichoderma harzianum cultivation and green forages

The increase in sheep populations to meet the demand for meat generates large volumes of sheep wool, most of which is considered agro-industrial waste and poses a potential risk of contamination due to improper handling. Protein recovery is an attractive strategy for generating agricultural inputs, such as protein hydrolysates (PHs). This study aimed to evaluate the agrobiotechnological potential of sheep wool-derived PHs as (i) an alternative peptone source for Trichoderma harzianum and (ii) growth-promoting inputs in hydroponic green fodder (HGF) production. To this end, an alkaline-enzymatic hydrolysis process was evaluated, incorporating pretreatment with an anionic surfactant applied to sheep wool. SDBS-pretreated wool underwent alkaline solubilization (2.5% NaOH) followed by enzymatic hydrolysis using Esperase® or papain. The process achieved 90-92% solubilization and 29-39% hydrolysis, producing peptides of 10-2 kDa and increasing soluble nitrogen and primary amino groups. Compounds with reducing capacity were also detected without affecting antioxidant activity (FRAP and DPPH), particularly in the Esperase®. Sheep wool hydrolysates used as a peptone source promoted moderate mycelial growth and sporulation of T. harzianum, while enhancing enzymatic activity associated with biological control potential, as indicated by increased halo diameters. Furthermore, foliar application of hydrolysates at 3 g L−¹ in HGF promoted greater shoot length (8.2–9.6%) and higher total protein content (27.2%) compared to the control, along with an increase in dry matter content (4.1%). Overall, alkaline-enzymatic hydrolysis of sheep wool represents a promising strategy to produce bio-based inputs for microbial culture and plant growth.