Volume 56, Issue No. 3

    https://doi.org/10.17113/ftb.56.03.18.5546 

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

Arijana Bušić¹, Nenad Marđetko¹, Semjon Kundas²,  Galina Morzak³,  Halina Belskaya³,  Mirela Ivančić Šantek¹, Draženka Komes¹, Srđan Novak¹ and  Božidar Šantek¹*

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

Summary:
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:  +38514605290
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    https://doi.org/10.17113/ftb.56.03.18.5736 

Lactic Acid Bacteria as Biological Control of Staphylococcus aureus in Coalho Goat Cheese

Rânmilla Cristhina Santos Castro, Anay Priscilla David de Oliveira, Eline Almeida Rodrigues de Souza, Tayla Marielle Antunes Correia, Jane Viana de Souza and Francesca Silva Dias*

Federal University of San Francisco Valley, Rod. BR 407, Km 12, Lote 543, Projeto de Irrigação Senador Nilo Coelho, s/nº, C1, BR-56.300-990 Petrolina, Pernambuco, Brazil

Article history:
Received: 21 February 2018
Accepted: 23 May 2018 
 

Key words:
coalho goat cheese, pathogens, multidrug resistance, staphylococcal enterotoxins, microbiological safety, technofunctional properties of Enterococcus faecium

Summary:
The aim of this study is to investigate the bacterial population in coalho goat cheese produced in the semi-arid northeast region of Brazil, to analyse the antibiotic resistance profiles of the identified pathogenic bacteria, to detect the staphylococcal enterotoxin genes and to evaluate the addition of autochthonous lactic acid bacteria (LAB) with technofunctional properties for the control of Staphylococcus aureus growth. In the analysed samples, strains of Escherichia coli (N=11), Salmonella spp. (N=18), Listeria spp. (N=6) and S. aureus (N=9) were classified as multidrug resistant (MDR). The most commonly isolated pathogen from the studied coalho goat cheese was S. aureus. Its isolates were positive for the genes encoding enterotoxins A (sea), B (seb), C (sec) and D (sed). The autochthonous LAB with the potential to inhibit S. aureus were identified as Enterococcus faecium. These strains were selected for in vitro tests of protective, safety, technological and functional properties. In the coalho goat cheese food matrix, these selected autochthonous LAB were able to reduce the enterotoxigenic MDR S. aureus load by approx. 3 log units.

*Corresponding author:  +558721014839
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    https://doi.org/10.17113/ftb.56.03.18.5658 

Microbial Keratinases: Enzymes with Promising Biotechnological Applications

Beti Vidmar and Maša Vodovnik*

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

Summary:
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:  +38613203955
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