Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt Using brewer's spent grain to formulate culture media for the production of bacteriocins using Patagonian strains Alicia Paz a,b , Sabrina da Silva Sabo a,b,c , Marisol Vallejo d , Emilio Marguet d , Ricardo Pinheiro de Souza Oliveira c , José Manuel Domínguez a,b,* a Department of Chemical Engineering, Faculty of Sciences, University of Vigo (Campus Ourense), As Lagoas s/n, 32004 Ourense, Spain b Laboratory of Agro-food Biotechnology, CITI (University of Vigo)-Tecnópole, Parque Tecnológico de Galicia, San Cibrao das Viñas, 32900 Ourense, Spain c Department of Biochemical and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, University of São Paulo, Av. Lineu Prestes 580, Bl 16, 05508-900, São Paulo, Brazil d Cátedra de Biología Celular y Molecular, Facultad de Ciencias Naturales (FCN), Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB), Sede Trelew. Roca 115, 1º Piso, 9100 Trelew, Chubut, Argentina ARTICLE INFO Keywords: Brewer's spent grain Bacteriocins Lactococcus lactis Enterococcus mundtii Listeria monocytogenes ABSTRACT This study evaluates the use of hemicellulosic hydrolyzates, derived from brewer's spent grain (BSG), as a means of generating bacteriocins. The producer strains, Lactococcus lactis Tw11 and Enterococcus mundtii Tw492, were isolated from animals of Argentine Patagonia. Different culture formulations were tested, and antimicrobial activity was determined against Listeria monocytogenes CECT-934. The presence of Tween 80 allowed the release of bacteriocins produced by both strains, with inhibition halos of 15.46 mm ± 0.05 using L. lactis Tw11, and 24.47 mm ± 0.09 using E. mundtii Tw492. Also, under these conditions the concentration of lactic acid was seen to increase to 3.21 g L -1 ± 0.12 using L. lactis Tw11, yet remained very similar (2.45 g L -1 ± 0.01) with E. mundtii Tw492. The activity of the bacteriocins was scarcely affected by additional supplementation with salts. This research suggests that BSG and other similar materials can be used in the production of bacteriocins em- ploying ecofriendly methods. 1. Introduction The European Union, with a production of 383 million hectoliters of beer in 2014, has become the second largest beer producer in the world after China (The Brewers of Europe, 2016). During the brewing process, malted barley is subjected to enzymatic degradation, which releases fermentable (maltose and maltotriose) and non-fermentable (other dextrins) carbohydrates, as well as soluble proteins, polypeptides and amino acids. This medium, which is fermented into beer, is called wort, and the insoluble grain components are called brewer's spent grain (BSG) (Lynch, Steffen, & Arendt, 2016; Russ, Mörtel, & Meyer-Pittroff, 2005). The worldwide annual production of BSG has been estimated at approximately 38.6 million tons (Mussatto, 2014). BSG is a lig- nocellulosic material consisting mainly of sugars, but also contains proteins and minerals. Its composition varies depending on the brewing processes, the point of harvest, the type of cereal, and the adjuncts used (Lynch et al., 2016; Mussatto, 2014; Santos, Jiménez, Bartolomé, Gómez-Cordovés, & Del Nozal, 2003). BSG is rich in protein (20–25% dry matter), fiber and energy, and for this reason has traditionally been used as animal feed (Lynch et al., 2016; Mussatto, 2014). More recently its possible applications for human food have been discussed. For ex- ample, the protein fraction is of interest here due to its high levels of essential amino acids with antioxidant properties (Niemi, Martins, Buchert, & Faulds, 2013; Vieira, da Silva, Carmo, & Ferreira, 2017). BSG also has applications in biotechnology for the generation of culture media, since its cell walls can be degraded into their con- stituents by hydrolytic processes, such as glucose from cellulose, and xylose, mannose, galactose, arabinose, hydroxycinnamic and acetic acids from non-cellulosic polysaccharides (Mussatto, 2014). Although a wide variety of hydrolytic procedures have been reported in the lit- erature, not all of these are suitable, since the sugars released can de- grade under harsh conditions, with the consequent formation of un- desirable compounds and inhibitors, such as furfural and hydroxymethylfurfural (Jönsson & Martín, 2016; Mussatto & Roberto, 2006). One of the most common treatments consists of a pre-treatment based on acid hydrolysis (prehydrolysis) that allows the hemicellulosic fraction to solubilize in its constituent monomers (Mussatto & Roberto, 2005; Mussatto, Dragone, & Roberto, 2007). Hence, the released sugars could be used by microbial transformation as precursors of enzymes https://doi.org/10.1016/j.lwt.2018.05.027 Received 8 January 2018; Received in revised form 9 May 2018; Accepted 9 May 2018 * Corresponding author. Department of Chemical Engineering, Faculty of Sciences, University of Vigo (Campus Ourense), As Lagoas s/n, 32004 Ourense, Spain. E-mail address: jmanuel@uvigo.es (J.M. Domínguez). LWT - Food Science and Technology 96 (2018) 166–174 Available online 10 May 2018 0023-6438/ © 2018 Elsevier Ltd. All rights reserved. T