Functional properties of novel protective lactic acid bacteria and application in raw chicken meat against Listeria monocytogenes and Salmonella enteritidis Petros A. Maragkoudakis a , Konstantinos C. Mountzouris b , Dimitris Psyrras a , Silvia Cremonese a,c , Jana Fischer d , Mette D. Cantor d,1 , Effie Tsakalidou a, ⁎ a Department of Food Science and Technology, Agricultural University of Athens, Iera Odos 75,118 55 Athens, Greece b Department of Nutritional Physiology and Feeding, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece c Dipartimento Scientifico e Tecnologico, Facolta di Scienze MM. FF. NN., University of Verona, Strada le Grazie,15, 37134 Verona, Italy d Danisco A/S, Edwin Rahrs Vej 38. 8220 Brabrand, Denmark abstract article info Article history: Received 9 October 2008 Received in revised form 20 January 2009 Accepted 21 January 2009 Keywords: Lactic acid bacteria Protective Antimicrobial Chicken Salmonella Listeria In this study 635 lactic acid bacteria of food origin were evaluated for their potential application as protective cultures in foods. A stepwise selection method was used to obtain the most appropriate strains for application as protective cultures in chicken meat. Specifically, all strains were examined for antimicrobial activity against various Gram positive and Gram negative pathogenic and spoilage bacteria. Strains exhibiting anti-bacterial activity were subsequently examined for survival in simulated food processing and gastrointestinal tract conditions, such as high temperatures, low pH, starvation and the presence of NaCl and bile salts. Selected strains where then examined for basic safety properties such as antibiotic resistance and haemolytic potential, while their antimicrobial activity was further investigated by PCR screening for possession of known bacteriocin genes. Two chosen strains were then applied on raw chicken meat to evaluate their protective ability against two common food pathogens, Listeria monocytogenes and Salmonella enteritidis, but also to identify potential spoilage effects by the application of the protective cultures on the food matrix. Antimicrobial activity in vitro was evident against Gram positive indicators, mainly Listeria and Brochothrix spp., while no antibacterial activity was obtained against any of the Gram negative bacteria tested. The antimicrobial activity was of a proteinaceous nature while strains with anti-listerial activity were found to possess one or more bacteriocin genes, mainly enterocins. Strains generally exhibited sensitivity to pH 2.0, but good survival at 45 °C, in the presence of bile salts and NaCl as well as during starvation, while variable survival rates were obtained at 55 °C. None of the strains was found to be haemolytic while variable antibiotic resistance profiles were obtained. Finally, when the selected strains Enterococcus faecium PCD71 and Lactobacillus fermentum ACA-DC179 were applied as protective cultures in chicken meat against L. monocytogenes and S. enteritidis respectively, a significantly reduced growth of these pathogenic bacteria was observed. In addition, these two strains did not appear to have any detrimental effect on biochemical parameters related to spoilage of the chicken meat. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Fermented foods and beverages of all types have played a major role in human nutrition since the beginning of recorded human history. The enhanced preservation characteristics of fermented foods confer a pivotal advantage, still crucial for food preservation in less developed societies where refrigeration is still scarce. In modern societies, increasing consumer awareness and desire for natural products and processes emphasises the concept of biopreservation as a natural alternative for food preservation (Stiles, 1995). This includes the use of safety-enhancing bacteria in fermented foods known as protective cultures (Holzapfel et al., 1995). Lactic acid bacteria (LAB), in particular, constitute the most appropriate choice for application as protective cultures, since they are present in all fermented foods, have a long history of safe use and form part of the gut microflora of humans and animals. In addition, LAB produce a range of antimicrobial substances such as organic acids and bacteriocins that have been already exploited by the food industry. Promising LAB strains or their metabolic products have been applied in food against pathogens, mainly L. monocytogenes, in dairy products such as soft and hard cheese (Samelis et al., 2003; Foulquie Moreno et al., 2003a,b; Liu et al., 2008) and meat products such as sausages and ham (Callewaert et al., 2000; Ananou et al., 2005; Marcos et al., 2008). In addition, protective LAB cultures have International Journal of Food Microbiology 130 (2009) 219–226 ⁎ Corresponding author. Tel.: +302105294661; fax: +305294672. E-mail address: et@aua.gr (E. Tsakalidou). 1 Chr. Hansen A/S, Boege Alle 10-12, 2970 Hoersholm, Denmark. 0168-1605/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2009.01.027 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro