Exploring the potential of spore surface-displayed keratinase for feather waste degradation using high-throughput...

With the development of the global poultry industry, millions of tons of feathers are produced each year. A significant proportion is improperly discarded, leading to a substantial loss of keratin resources from feathers. Utilizing feathers in the feed industry could reduce costs substantially. However, the new fermented feed industry lacks acid-resistant keratinase, making it unable to convert feather keratin effectively in a lactic acid bacteria fermentation environment.

This study established a high-throughput screening method using spore surface-display to identify acid-resistant mutants generated by error-prone PCR. A mutant H4 (N43K/N143I) was obtained with a significant increase in activity under acidic conditions, and it was 1.34-fold more active than the wild type in a pH 5 environment. Bioinformatic analysis showed that the increase in stress resistance and activity of H4 was due to an increase in certain weak interaction forces and alterations in energy levels. The addition of H4 spore suspension as an enzyme preparation to feather meal fermentation feed with the participation of lactic acid bacteria improved the content of small peptides and free amino acids significantly. After being subjected to short-term high-temperature treatments, the H4 spore preparation was still able to degrade chicken feathers.

These results suggest that the spore surface-displayed keratinase mutant H4 has potential for improved effectiveness in feather degradation within the fermented feed industry. © 2025 Society of Chemical Industry.