# Feather Waste Biodegradation and Biostimulant Potential of Gordonia alkanivorans S7: A Novel Keratinolytic Actinobacterium for Sustainable Waste Valorization

## TL;DR

A new bacteria, Gordonia alkanivorans S7, can break down chicken feathers into a plant-friendly fertilizer, offering a sustainable waste solution.

## Contribution

This is the first study to show keratinolytic activity in the Gordonia genus for feather waste valorization.

## Key findings

- Gordonia alkanivorans S7 achieved up to 99% dry mass loss of chicken feathers in 168 hours.
- The resulting keratin hydrolysate stimulated plant root growth by up to 31% and shoot growth by up to 53%.
- The process offers an environmentally sustainable and economically viable solution for keratin waste.

## Abstract

The poultry industry produces significant quantities of keratin-rich waste, primarily feathers, whose traditional disposal methods—incineration or chemical treatment—result in environmental damage and resource depletion. This research introduces a sustainable biotechnological method for the valorization of feather waste utilizing Gordonia alkanivorans S7, an actinomycete strain extracted from petroleum plant sludge. This is the inaugural publication illustrating keratinolytic activity in the Gordonia genus. The optimization of the degradation process via the Taguchi approach led to the effective biodegradation of untreated home chicken feathers, achieving dry mass loss of up to 99% after 168 h in a mineral medium. The agricultural potential of the obtained keratin hydrolysate, which was high in organic components (C 31.2%, N 8.9%, H 5.1%, and S 1.7%), was assessed. Phytotoxicity tests demonstrated that the feather hydrolysate led to better growth of the indicator plants—Sorghum saccharatum and Lepidium sativum. The highest values of root growth stimulation were 26% for S. saccharatum and 31% for L. sativum, at a dose of 0.01%. Shoot growth stimulation was noted only for L. sativum, reaching 38% (0.01%), 53% (0.05%), and 37% (0.1%), as compared to the control sample. These results demonstrate the process’s combined economic and environmental benefits, providing a fresh approach to the production of bio-based plant biostimulants and sustainable keratin waste management.