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Microbial Keratinases: Enzymes with Promising Biotechnological Applications


Beti Vidmarorcid tiny and Maša Vodovnik*orcid tiny


Chair of Microbiology and Microbial Biotechnology, Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, SI-1230 Domžale, Slovenia



Article history:
Received: 3 January 2018
Accepted: 31 May 2018 


Key words:
keratin, keratinase, waste degradation, keratinolytic microorganisms, biotechnological applications



Keratin is a complex and structurally stable protein found in human and animal hard tissues, such as feathers, wool, hair, hoof and nails. Some of these, like feathers and wool, represent one of the main sources of protein-rich waste with significant potential to be transformed into value-added products such as feed, fertilizers or bioenergy. A major limitation impeding valorization of keratinous substrates is their recalcitrant structure and resistance to hydrolysis by common proteases. However, specialized keratinolytic enzymes produced by some microorganisms can efficiently degrade these substrates. Keratinases have already found a purpose in pharmaceutical, textile and leather industries. However, their wider implementation in other processes, such as cost-effective (pre)treatment of poultry waste, still requires optimization of production and performance of the available enzymes. Here we present a comprehensive review covering molecular properties and characteristics of keratinases, their classification, traditional and novel approaches in discovery of novel enzymes, production, characterization, improvement and biotechnological applications.



*Corresponding author: tel3 +38613203955
                                          fax2 +38617241005

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Bioethanol Production from Renewable Raw Materials and Its Separation and Purification: A Review

Arijana Bušić1orcid tiny, Nenad Marđetko1orcid tinySemjon Kundas2orcid tiny,  Galina Morzak3orcid tiny,  Halina Belskaya3orcid tiny,  Mirela Ivančić Šantek1orcid tinyDraženka Komes1orcid tiny, Srđan Novakand  Božidar Šantek1*orcid tiny


1University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva 6, HR-10000 Zagreb, Croatia
2Belarussian National Technical University, Power Plant Construction and Engineering Services Faculty, Nezavisimosti Ave. 150, BY-220013 Minsk, Belarus
3Belarussian National Technical University, Mining Engineering and Engineering Ecology Faculty, Nezavisimosti Ave. 65, BY-220013 Minsk, Belarus



Article history:
Received: 22 October 2017
Accepted: 21 May 2018 


Key words:
bioethanol, renewable feedstocks, raw material pretreatment, bioprocess operational modes, bioethanol separation and purification



Production of biofuels from renewable feedstocks has captured considerable scientific attention since they could be used to supply energy and alternative fuels. Bioethanol is one of the most interesting biofuels due to its positive impact on the environment. Currently, it is mostly produced from sugar- and starch-containing raw materials. However, various available types of lignocellulosic biomass such as agricultural and forestry residues, and herbaceous energy crops could serve as feedstocks for the production of bioethanol, energy, heat and value-added chemicals. Lignocellulose is a complex mixture of carbohydrates that needs an efficient pretreatment to make accessible pathways to enzymes for the production of fermentable sugars, which after hydrolysis are fermented into ethanol. Despite technical and economic difficulties, renewable lignocellulosic raw materials represent low-cost feedstocks that do not compete with the food and feed chain, thereby stimulating the sustainability. Different bioprocess operational modes were developed for bioethanol production from renewable raw materials. Furthermore, alternative bioethanol separation and purification processes have also been intensively developed. This paper deals with recent trends in the bioethanol production as a fuel from different renewable raw materials as well as with its separation and purification processes.



*Corresponding author: tel3 +38514605290
                                          fax2 +38514836424  

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