Revalorization of chicken feather waste into a high antioxidant activity feather protein hydrolysate using a novel psychrotolerant bacterium

Abstract

In this study, we assessed the capacity of Pedobacter sp. 3.14.7 —a novel Antarctic keratinolytic bacterium— of producing a feather protein hydrolysate (FPH) with high antioxidant activity. This strain was able to degrade raw feather into protein hydrolysate under optimal conditions of 30 g l−1 of feather concentration, pH 6.0, and 20 °C. Maximum enzymatic activity was detected after a 192-h cultivation period (125.67 ± 3.06 U ml−1). Quenching of the ABTS radical (2,20-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid) by the hydrolysate reached a value of approximately 95%, with a 50% Inhibitory Concentration (IC50) value of 0.57 ± 0.01 g l−1. An interesting reducing power of the FPH towards Fe+3 was also detected (2.19 Abs700 units in the presence of 2.03 g l−1 protein). The hydrolysate also displayed a moderate nitric oxide-scavenging activity, with an IC50 of 0.53 ± 0.01 g l−1. This FPH's free amino acid content is high (almost 5 g l−1). Results indicate that this hydrolysate may be useful as supplementary protein and antioxidant in animal feed formulations.