Keratin wastes are abundantly available but rich in hard-degrading fibrous proteins, and the keratinase-producing microorganisms have gained significant attention due to their biodegradation ability against keratinous materials. In order to improve the degradation efficiency of feather keratins, the keratinase gene (kerJY-23) from our previously isolated feather-degrading Ectobacillus sp. JY-23 was overexpressed in Bacillus subtilis WB600 strain. The recombinant KerJY-23 strain degraded chicken feathers rapidly within 48 h, during which the activities of disulfide reductase and keratinase KerJY-23 were sharply increased, and the free amino acids especially the essential phenylalanine and tyrosine were significantly accumulated in feather hydrolysate. The results of structural characterizations including scanning electron microscopy, Fourier transform infrared spectrum, X-ray diffraction, and X-ray photoelectron spectroscopy, demonstrated that the feather microstructure together with the polypeptide bonds and SS bonds in feather keratins were attacked and destroyed by the recombinant KerJY-23 strain. Therefore, the recombinant KerJY-23 strain contributed to feather degradation through the synergistic action of the secreted disulfide reductase to break the SS bonds and keratinase (KerJY-23) to hydrolyze the polypeptide bonds in keratins. This study offers a new insight into the underlying mechanism of keratin degradation, and provides a potential recombinant strain for the valorization of keratin wastes. 

Effective biodegradation on chicken feather by the recombinant KerJY-23 Bacillus subtilis WB600: A synergistic process coupled by disulfide reductase and keratinase.

The unique role of keratinases in keratin hydrolysis has garnered huge interest in the recovery of feather waste. However, owing to the high hydrophobicity of feather keratins, the catalytic capacity of keratinases for hydrolyzing feathers is typically low. In this study, we aimed to improve the keratinase feather hydrolysis efficiency by fusing a substrate-binding domain into the enzyme. We screened several carbohydrate-binding modules (CBMs) and linking peptides. We selected the most promising candidates to construct, clone, and express a fusion keratinase enzyme KerZ1/CBM-L8 with a feather hydrolysis efficiency of 7.8 × 10-8 g/U. Compared with those of KerZ1, KerZ1/CBM-L8 has a feather hydrolysis efficiency that is 2.71 times higher, a kcat value that is 179% higher, which translates to higher catalytic efficiency, and Km and binding constant (K) values that are lower, which indicate a higher KerZ1/CBM-L8-keratin binding affinity. Moreover, the number of binding sites to the substrate (N), determined using isothermal titration calorimetry, was 24.1 times higher than that of KerZ1. Thus, the fusion of the substrate-binding domain improved the binding ability of the keratinase enzyme to the hydrophobic substrate, which improved its feather hydrolysis efficiency. Therefore, using the fusion keratinase would significantly improve the recovery of feather waste.

Fusion of Substrate-Binding Domains Enhances the Catalytic Capacity of Keratinases and Promotes Enzymatic Conversion of Feather Waste.

Effective hydrolysis of feather waste by keratinase is an important way to develop high-quality alternative proteins for feed. It has been shown that the reduction of disulfide bonds is the key rate-limiting step in the hydrolysis of feathers by keratinases. However, the reductive activity of keratinase itself is low. In order to increase the reductive activity of the catalytic system, we screened endogenous disulfide reductase from Bacillus subtilis and constructed a synergistic catalytic system, KerZ1/yjbI-S2-P1, consisting of keratinase and disulfide reductase by co-expression optimization. The reductive activity and feather hydrolytic activity of the synergistic system were 5.67-fold and 5-fold higher than the original system. Feathers were hydrolyzed to a higher extent compared with the original system. The total amino acid and soluble protein concentrations in the products increased by 99% and 59%, respectively. This study provides a more environmentally friendly and efficient reduction capability for keratinase to hydrolysis waste feathers, and also demonstrates a new way of alternative protein feedstock mining. 

A synergistic catalytic system of keratinases and disulfide reductases for the bioconversion of feather wastes to feed alternative protein

KerJY-23 was a novel keratinase from feather-degrading Ectobacillus sp. JY-23, but its enzymatic characterization and structure are still unclear. In this study, the KerJY-23 was obtained by heterologous expression in Escherichia coli BL21(DE3), and enzymatic properties indicated that KerJY-23 was optimal at 60 °C and pH 9.0 and could be promoted by divalent metal ions or reducing agents. Furthermore, KerJY-23 had a broad substrate specificity towards casein, soluble keratin, and expanded feather powder, but its in vitro degradation against chicken feathers required an additional reducing agent. Homology modeling indicated that KerJY-23 contained a highly conserved zinc-binding HELTH motif and a His-Asp-Ser catalytic triad that belonged to the typical characteristics of M4-family metallo-keratinase and serine-keratinase, respectively. Molecular docking revealed that KerJY-23 achieved a reinforced binding on feather keratin via abundant hydrogen bonding interactions. This work not only deepened understanding of the novel and interesting metallo-serine keratinase KerJY-23, but also provided a theoretical basis for realizing the efficient use of waste feather keratin. 

Structural and enzymatic characterization of a novel metallo-serine keratinase KerJY-23.

Microbial degradation of feathers offers potential for bioremediation, yet the microbial response mechanisms warrant additional investigation. In prior work, Pseudomonas aeruginosa Gxun-7, which demonstrated robust degradation of feathers at elevated concentrations, was isolated. However, the molecular mechanism of this degradation remains only partially understood. To investigate this, we used RNA sequencing (RNA-seq) to examine the genes that were expressed differentially in P. aeruginosa Gxun-7 when exposed to 25 g/L of feather substrate. The RNA-seq analysis identified 5571 differentially expressed genes; of these, 795 were upregulated and 603 were downregulated. Upregulated genes primarily participated in proteolysis, amino acid, and pyruvate metabolism. Genes encoding proteases, as well as those involved in sulfur metabolism, phenazine synthesis, and type VI secretion systems, were notably elevated, highlighting their crucial function in feather decomposition. Integration of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) taxonomies, combined with a review of the literature, led us to propose that metabolic feather degradation involves environmental activation, reducing agent secretion, protease release, peptide/amino acid uptake, and metabolic processes. Sulfite has emerged as a critical activator of keratinase catalysis, while cysteine serves as a regulatory mediator. qRT–PCR assay results for 11 selected gene subset corroborated the RNA-seq findings. This study enhances our understanding of the transcriptomic responses of P. aeruginosa Gxun-7 to feather degradation and offers insights into potential degradation mechanisms, thereby aiding in the formulation of effective feather waste management strategies in poultry farming.

A Comparative Transcriptome Analysis Unveils the Mechanisms of Response in Feather Degradation by Pseudomonas aeruginosa Gxun-7

Research progress on the degradation mechanism and modification of keratinase

Diatoms are ideal aquaculture baits because they are not only rich in products with added value, such as eicosapentaenoic acid (EPA), docosahexaenoic acid, chrysolaminarin, and fucoxanthin (Fx) but also substantial primary producers in aquaculture. It is difficult to cultivate diatoms at a high density using traditional photoautotrophy. For improving diatom growth rate, biomass, and metabolites, mixotrophy and heterotrophy employing organic carbon sources are promising. However, preparing a conventional single organic carbon source is complicated and costly. This paper reviews the diatom species that can utilize organic carbon, the types of organic carbon used by diatoms (saccharides, alcohols, carboxylic acids, nitrogenous organic carbon, phenols), and the main bottlenecks and technical means of diatom heterotrophy and mixotrophy from an aquaculture perspective. For the first time, the impact of fermented feed on diatom culture was discussed to guide the development of a more efficient and practical nutrient supplement to promote. 

Progress in the cultivation of diatoms using organic carbon sources

The flexible linker and CotG were more effective for the spore surface display of keratinase KERQ7

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Zhen Wang

Author Tools

Chat about Author

Papers

Research progress on the degradation mechanism and modification of keratinase

Progress in the cultivation of diatoms using organic carbon sources

The flexible linker and CotG were more effective for the spore surface display of keratinase KERQ7