Kinetic of production and mode of action of the Lactobacillus paracasei subsp. paracasei anti-listerial bacteriocin, an Algerian isolate Farida Bendali a, * , Brigitte Gaillard-Martinie b , Michel Hebraud c , Djamila Sadoun a a Laboratoire de Microbiologie Applique´e, De´partement de Microbiologie, Faculte ´ des Sciences de la Nature et de la Vie, Universite´ A. Mira de Bejaia, Bejaia, Algeria b INRA Centre Clermont Ferrand – Theix, Plateau technique de Microscopie e´lectronique, 63122 Saint-Gene`s-Champanelle, France c INRA Centre Clermont Ferrand – Theix, UR454 Microbiologie, 63122 Saint-Gene`s-Champanelle, France article info Article history: Received 26 October 2007 Received in revised form 19 February 2008 Accepted 26 February 2008 Keywords: Lb. paracasei subsp. paracasei L. innocua CLIP 74915 L. monocytogenes EGDe Anti-bacterial activity Kinetic of production Cell lysis abstract Lactobacillus paracasei subsp. paracasei was isolated in our laboratory from breast-fed newborn faeces and identified phenotypically and genotypically. The strain was able to produce a bacteriocin-like sub- stance active towards listerial strains (Listeria innocua CLIP 74915 and Listeria monocytogenes EGDe). The maximum production of the substance by producing strain was detected in the late logarithmic growth phase (14 h in MRS and 18 h in BHI broths). It displayed bactericidal mode of action with leakage of cellular content (K þ and ATP) leading to cell lysis as secondary effect. A reduction of about 5 log with 35.7  0.2% of cell lysis and of about 4 log with 82.0  0.3% of cell lysis were observed, respectively, in a phosphate buffer and BHI suspensions. This was further demonstrated by electron microscopy that showed severe modifications in the cell morphology with a concomitant lysis. Ó 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. 1. Introduction Listeria monocytogenes is an opportunistic food-borne pathogen that infects primarily pregnant women, newborns and elderly (Tauxe, 2002). Numerous reviews have suggested that some lactic acid bacteria (LAB) were able to control the growth of this pathogen in food products (Ennahar, Aoude-Werner, Assobhei, & Hasselmann,1998; McAuliffe, Hill, & Ross, 1999; Mataragas, Drosinos, & Metaxopoulos, 2003). The anti-microbial effect exerted by LAB is due to the production of many compounds mainly organic acids, peroxide hydrogen and bacteriocins. Among them the latter have attracted a great interest due to their application in food preservation. During the last few years, a large number of new LAB-bacteriocins have been identified and characterized (Cuozzo et al., 2003; Lozo, Vukasinovic, Strahinic, & Topisirovic, 2004; Zendo, Koga, Shigeri, Nakayama, & Sonomoto, 2006). Bacteriocins are ribosomally synthesized, bioactive peptides or proteins which have a bactericidal or bacteriostatic effect on other species (Garneau, Martin, & Vederas, 2002). The modes of action of bacteriocins differ; generally the cytoplasmic membrane is their primary target. They dissipate the proton motive force through the formation of pores in the phospholipids bilayer. This action results in the inhibition of protein or nucleic acid bio- synthesis and loss of ions (Bauer & Dicks, 2005). In this work, we have investigated the kinetic of production and the mode of action of the bacteriocin-like substance produced by a strain of Lactobacillus paracasei subsp. paracasei, a faecal isolate. Strains of the so-called Lactobacillus casei group comprising the species Lb. casei, Lb. paracasei subsp. paracasei and subsp. tolerans and Lactobacillus rhamnosus are being increasingly applied in novel-type yoghurts as probiotics (Erdogrul & Erbilir, 2006) and as non starter LAB in the cheese manufacture (Morea, Matarante, Di Cagno, Baruzzi, & Minervini, 2007). The choice of this strain was directed by the fact that few reports deal with the anti-bacterial compounds produced by this species. Recently, Atanassova et al. (2003) reported the production of a bacteriocin (z43 kDa) by the strain Lb. paracasei subsp. paracasei M3, used as a starter for Bul- garian yellow cheese and Lozo et al. (2004) reported the production of bacteriocin 217 (Bac217; w7 kDa) by Lb. paracasei subsp. paracasei BGBUK2-16 from traditionally homemade white-pickled cheese. Understanding the mode of action of the bacteriocin would be important to allow effective utilization of this protein; in this sense, we have studied the mode of action of the substance produced by Lb. paracasei subsp. paracasei, on Listeria innocua and * Corresponding author. Tel.: þ213 034 21 43 33/34/35; fax: þ213 034 21 47 62. E-mail addresses: kamelea03@hotmail.com (F. Bendali), martinie@clermont. inra.fr (B. Gaillard-Martinie), hebraud@clermont.inra.fr (M. Hebraud), djsadoun@ yahoo.fr (D. Sadoun). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt LWT- Food Science and Technology 41 (2008) 1784–1792 Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$34.00 Ó 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2008.02.010