Efficient biodegradation of feathers by a novel and stable metallo-keratinase production strain Stenotrophomonas sp. Yang-5 isolated from swan farming soil

Abstract

Feather waste produced by livestock and poultry breeding industry is a kind of biomass resource with great application prospect. Current study aims to obtain a feather-degradation bacteria that could efficiently biodegrade feather waste and maintain environmental friendliness. By using the casein agar medium, a novel keratinase production strain Stenotrophomonas sp. Yang-5 was isolated and then identified by subsequent 16S rRNA sequence. Further keratinase production medium was optimized by single factor and orthogonal experiments. Also, crude keratinase was characterized. Consequently, the highest enzyme activity of 161.95 ± 3.65 U/mL was obtained after 48 h of incubation with optimized conditions consisting of reaction temperature 32.5 °C, initial pH 7.5, 0 g/L CaCl₂, 50 g/L fructose, and 15 g/L feather. Yang-5 keratinase demonstrated a broad temperature range of 25 °C − 95 °C and optimal catalytic efficiency at pH 9.0. The keratinase had a half-life of more than 120 min at 70° C, indicating satisfactory thermal stability. Furthermore, 0.25 mol/L Mg²⁺, Mn²⁺, K⁺, and Ca²⁺ could enhance the enzyme activity to some extent and assigned as the metallo-class of keratinase, among of which Mn²⁺ resulted in the highest improvement by 2-fold activity enhancement. In addition, 5% (v/v) reducing agents including DMSO, DTT and 2-mercaptoethanol all reinforced the enzyme activity by 3–5 folds. To sum up, thermostable alkaline metallo-keratinase from Stenotrophomonas sp. Yang-5 exhibited favorable stability and could serve as a promising candidate for feather waste degradation as well as environmental protection and feed additive industry.

Graphical Abst ract

Keywords:

• Feather waste
• biodegradation
• keratinase
• biochemical characterization
• thermal stability

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All authors are consent to publish.

Authors’ contributions

Zhi Chen conducted the experiments and draft of the manuscript as well as the revision. Xiangjing Xu helped the proofreading for the manuscript. Xin Ju, Lishi Yan and Liangzhi Li helped the experiment design and figures preparation. Dongzhi Wei provided the resource. All authors read and approved the final manuscript.

Disclosure statement

The authors declare that they have no conflict of interest.

Data availability statement

All datasets generated for this study are included in the article. The data used to support the findings of this study are available from the corresponding author upon request.

Additional information

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.