AbstractKeratin, the main structural constituent of feathers, contains a lot of valuable amino acids which are potential bioactive compounds as well. Since conventional methods are not efficient enough to achieve complete removal of chicken feather waste, biological mode of feather degradation is one of the most appropriate ways to utilize feathers, thereby reducing wastes as well as generating value-added products from feathers. This study was focussed on valorizing chicken feather into feather hydrolysate (FH) containing bioactive compounds for plant growth promotion. Keratinolytic bacteria capable of degrading chicken feathers were isolated from the poultry waste dumping site of Russell Market, Shivajinagar, Bangalore, Karnataka, India. The isolated bacteria was identified as Bacillus tropicus LS 27. A minimal media with chicken feather as the sole source of carbon and nitrogen was prepared and inoculated with Bacillus tropicus LS 27 [5% (v/v)]. Degradation of keratin protein by bacteria caused the solubilization of amino acids which was confirmed by high-performance liquid chromatography (HPLC) analysis where an appreciable amount of amino acids like cysteine, valine, isoleucine, proline, lysine, methionine, and phenylalanine was detected. The Fourier transform infrared spectroscopy (FTIR) analysis of hydrolysed chicken feathers showed C=0 stretching, S-H bond stretching, and formation of carboxylic acid groups indicating effective degradation of chicken feathers. Scanning electron microscope (SEM) images revealed the degradation pattern of feathers showing complete degradation of barbs and barbules with a portion of rachis remaining. Feather hydrolysate was further explored for its antioxidant activity using DPPH scavenging assay, and the value was found to be 1.5 mg/mL. The bacterial cells when screened for heavy metal tolerance showed significant metal tolerance to lead (Pb) and chromium (Cr). Since Bacillus tropicus LS27 showed indole-3-acetic acid (IAA), siderophore, and ammonia production, the prepared feather hydrolysate along with the bacterial cells were used as soil amendment for plant growth studies over Spinacia oleracea L. The study revealed that plants supplemented with 20% (v/v) FH showed elevated plant growth, therefore proving to be optimum for the support of plant growth.Graphical abstract