Bacterial competition: A proteomic study of Lactococcus lactis and Listeria monocytogenes

BACTERIAL COMPETITION: A PROTEOMIC STUDY OF LACTOCOCCUS LACTIS AND LISTERIA MONOCYTOGENES I. Alloggioa, C. Pirasa, , A. Soggiua, V. Grecob , E. Coscianic, N. Losioc, A. Urbanib,d, L. Bonizzia, P. Roncadaa,e. a DIVET, Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Italy b Fondazione Santa Lucia – IRCCS, Rome, Italy c Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Brescia, Italy d Department of Experimental Medicine and Surgery, University of Rome “Tor Vergata”, Rome, Italy e Istituto Sperimentale Italiano L. Spallanzani, Milano, Italy Listeria monocytogenes (LM) is an ubiquitous pathogen responsible of listeriosis. The mortality rate is close to 24% mainly in immunocompromised persons (1). In the spreading of this pathology milk and dairy products often represent a key point as reservoir for this pathogen (2). This represents a serious burden if considering the possibility of human infection and the financial loss due to the strict rules for food exportation. In particular food processing represents one of the major steps that could be associated to LM growth (3). It has been documented how, in food processing, the contamination is probably due to the presence of LM after the first post-pasteurization process of milk (4). Inhibition of LM growth through the competition of other bacteria could represent a solution to this problem. In particular the production of bacteriocins by some species of Lactococcus could play a key role in pathogens growth inhibition (5). Aim of this work is to study in vitro the exoproteome different strains of Lactococcus lactis growing in competition with LM in order to highlight the molecular mechanisms involved in this process and to give new insight to counteract the pathogen by use natural lactic acid bacteria. Work supported by Ministry of Health CCM Project : Milano EXPO 2015 (LB) References 1. Farber, J.; Peterkin, P., Listeria monocytogenes, a food-borne pathogen. Microbiological reviews 1991, 55, (3), 476. 2. Greenwood, M. H.; Roberts, D.; Burden, P., The occurrence of Listeria species in milk and dairy products: a national survey in England and Wales. International journal of food microbiology 1991, 12, (2), 197-206. 3. Northolt, M.; Beckers, H.; Vecht, U.; Toepoel, L.; Soentoro, P.; Wisselink, H., Listeria monocytogenes: heat resistance and behaviour during storage of milk and whey and making of Dutch types of cheese. Netherlands Milk and Dairy Journal 1988, 42. 4. Kozak, J.; Balmer, T.; Byrne, R.; Fisher, K., Prevalence of Listeria monocytogenes in foods: Incidence in dairy products. Food Control 1996, 7, (4), 215-221. 5. Stecchini, M. L.; Aquili, V.; Sarais, I.; Pitotti, A., Inhibition of Listeria monocytogenes by Lactococcus lactis subsp. lactis isolated from Italian raw ham. Journal of food safety 1992, 12, (4), 295-302.