RESEARCH ARTICLE Heterologous expression and purification of keratinase from Actinomadura viridilutea DZ50: feather biodegradation and animal hide dehairing bioprocesses Mouna Ben Elhoul 1,2 & Nadia Zaraî Jaouadi 1,2 & Khelifa Bouacem 3 & Fawzi Allala 3 & Hatem Rekik 1,2 & Sondes Mechri 1 & Haifa Khemir Ezzine 4 & Neila Miled 4 & Bassem Jaouadi 1,2 Received: 2 April 2020 /Accepted: 21 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract The keratin-degrading bacterium Actinomadura viridilutea DZ50 secretes a keratinase (KERDZ) with potential industrial inter- est. Here, the kerDZ gene was extracellularly expressed in Escherichia coli BL21(DE3)pLysS using pTrc99A vector. The recombinant enzyme (rKERDZ) was purified and biochemically characterized. Results showed that the native and recombinant keratinases have similar biochemical characteristics. The conventional dehairing with lime and sodium sulfide degrades the hair to the extent that it cannot be recovered. Thus, these chemical processes become a major contributor to wastewater problem and create a lot of environmental concern. The complete dehairing was achieved with 2000 U/mL rKERDZ for 10 h at 40 °C. In fact, keratinase assisted dehairing entirely degraded chicken feather (45 mg) and removed wool/hair from rabbit, sheep, goat, or bovine’ hides (1.6 kg) while preserving the collagen structure. The enzymatic process is the eco-friendly option that reduces biological (BOD) (50%) and chemical (COD) oxygen demands (60%) in leather processing. Consequently, the enzymatic hair removal process could solve the problem of post-treatments encountering the traditional leather processing. The enzymatic (rKERDZ) dehaired leather was analyzed by scanning electron microscopic (SEM) studies, which revealed similar fiber orien- tation and compactness compared with control sample. Those properties support that the rKERDZ enzyme–mediated process is greener to some extent than the traditional one. Keywords Heterologous expression . Keratinase . Feather degradation . Leather industry . Animal hide dehairing Introduction Part of the proteolytic enzymes group, keratinases (EC 3.4.21), catalyze the hydrolysis of keratins. These are recognized for their high stability and tightly packed protein structures through disulfide and hydrogen bonds. As a consequence, they are ex- tremely resistant to proteolytic breakdown with trypsin, papain, or pepsin (Xie et al. 2010). Keratinolytic enzymes are mainly obtained from bacteria and fungi (Gurav et al. 2020; Zaraî Jaouadi et al. 2015). Several actinomycetes were reported to produce keratinases with interesting biotechnological appli- cations (Habbeche et al. 2014). These enzymes made a focal point of interest for many investigations thanks to their broaden industrial uses, e.g., in agro-chemistry, food industry, or tan- nery (Sobucki et al. 2017). The classic methods in the leather process involve three prime ways: pre-tanning where hides or skins are cleaned using sodium sulfide (Na 2 S) and lime; tan- ning where the leather materials are stabilized with chromium Responsible Editor: Philippe Garrigues * Bassem Jaouadi bassem.jaouadi@cbs.rnrt.tn; biotechecozym@gmail.com 1 Laboratory of Microbial Biotechnology, Enzymatic, and Biomolecules (LMBEB), Centre of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour Km 6, P.O. Box 1177, 3018 Sfax, Tunisia 2 Biotech ECOZYM Start-up, Business Incubator, Centre of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour Km 6, P.O. Box 1177, 3018 Sfax, Tunisia 3 Laboratory of Cellular and Molecular Biology (LCMB), Microbiology Team, Faculty of Biological Sciences, University of Sciences and Technology of Houari Boumediene (USTHB), P.O. Box 32, El Alia, Bab Ezzouar, 16111 Algiers, Algeria 4 National Leather and Shoe Center (CNCC), 17, Road of leather, Z.I. Sidi Rezig, 2033 Ben Arous, Tunisia Environmental Science and Pollution Research https://doi.org/10.1007/s11356-020-11371-1