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Unveiling the keratinolytic transcriptome of the black carpet beetle (Attagenus unicolor) for sustainable poultry feather recycling

  • Genomics, Transcriptomics, Proteomics
  • Published:
Applied Microbiology and Biotechnology Aims and scope Submit manuscript


The black carpet beetle (BCB) is a household pest unique in its ability to digest complex proteins such as keratin that makes up the majority of feather structure. Despite voluminous yield and high protein content ( > 85%), feathers are poorly digested by most known organisms and are thereby rendered an environmental hazard. Furthermore, keratinolytic microbial strains are typically thermophilic and therefore economically and environmentally unsustainable. Given the BCB’s ability to digest wool, feathers, and other keratin-rich materials, we assembled a de novo transcriptome of larvae fed on either feathers or standard chow. All proteolytic enzymes were identified via homology to the MEROPS database and subsequently annotated for a complete overview of enzymatic activity and distribution of peptidase clans in the transcriptome. Both differential expression and sequence homology screening were then used to identify potentially keratinolytic candidates from the assembly to be used in future expression experiments. The BCB transcriptome showed a high proportion of serine (22.6%) and cysteine (18.9%) proteases as well as metallopeptidases (25.5%) compared with other insect species. Regarding differential expression, serine and metalloproteases represented a large proportion of upregulated genes in the feather-fed group, constituting 42.9% and 57.1% of upregulated proteases, respectively. Additionally, several candidate transcripts identified through homology screening showed significant sequence overlap to seven existing keratinases, indicating a strong likelihood of keratinolytic function in this organism.

Key points

A de novo transcriptome of black carpet beetle larvae was assembled.

The transcriptome consisted of 67% of serine, cysteine, and metalloproteases.

Differential transcriptomes of beetles fed feather and chow were compared.

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Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.


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We would like to thank Dr. Peter Schweitzer and Dr. Qi Sun at the Cornell University Institute of Biotechnology for their technical assistance during the construction of the transcriptome and subsequent data analysis. We would also like to thank Dr. Ping Wang in the Department of Entomology, Cornell University for his discussion and knowledge on insect biology related to this project. In addition, we thank Dr. Mark Mandli at SC Johnson’s Institute of Insect Science for Family Health for the generous donation of beetle cultures.


This project was supported in part by the USDA National Institute of Food and Agriculture grant NO: 2019-69012-29905.

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MK and XL conceived and designed research. MK conducted experiments, analyzed data, and composed the manuscript. XL edited the final draft. All authors have read and approved of the manuscript. Each author has substantially contributed to the knowledge and conductance of the research detailed within and drafting of this manuscript.

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Correspondence to Xin Gen Lei.

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All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. This article does not contain any studies involving human participants performed by any of the authors.

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Keefe, M., Lei, X.G. Unveiling the keratinolytic transcriptome of the black carpet beetle (Attagenus unicolor) for sustainable poultry feather recycling. Appl Microbiol Biotechnol 105, 5577–5587 (2021).

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