Wednesday, May 11, 2016
Megaron Athens International Conference Center
Evangelia Zilelidou, Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Varvara Milina, Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Spiros Paramithiotis, Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Georgia Zoumpopoulou, Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Eleni Mavrogonatou, Laboratory of Cell Proliferation and Ageing, Institute of Biosciences and Applications, National Centre for Scientific Research “Demokritos”, Athens, Greece
Konstantinos Papadimitriou, Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Dimitris Kletsas, Laboratory of Cell Proliferation and Ageing, Institute of Biosciences and Applications, National Centre for Scientific Research “Demokritos”, 153 10, Athens, Greece
Effie Tsakalidou, Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Panagiotis Skandamis, Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Introduction: The interactions between
Listeria monocytogenes and food-associated bacteria are critical for the growth of the microorganism in food environments and often related to under-detection of
L. monocytogenes during enrichment. However limited information exists on the impact of food microorganisms on the virulence of the pathogen.
Purpose: The study investigated: i) growth, ii) expression of virulence genes and iii) in vitro virulence potential of L. monocytogenesin the presence of four different food-related microorganisms.
Methods: Growth of L. monocytogenes (ScottA) was evaluated as monoculture or in co-culture with L. innocua, Bacillus subtilis, Lactobacillus plantarum and Pseudomonas aeruginosa in Tryptic Soy Broth (10°C/10 days and 37°C/24 hours). The transcription of 9 key virulence genes (inlA, inlB, inlC, inlJ, sigB, prfA, hly, plcA, plcB), in addition to invasion efficiency (45min) and intracellular growth (4h) in Caco-2 cells, were determined for L. monocytogenesgrown singly or in co-culture previously incubated for 3 days at 10°C or 9 hours at 37°C.
Results: Significant differences in growth between single and co-cultures of ScottA were observed when grown with L. innocua at 37°C or 10°C (e.g. lower final populations) and B. subtilis at 37°C (e.g. growth cessation after 9 h). ScottA revealed considerably increased invasion efficiency when co-cultured with L. innocua but attenuated, efficiency in the presence of B. subtilis. Intracellular growth of L. monocytogenes in Caco-2 cells was reduced up to 35 folds compared to monoculture, when grown in co-cultures. The key virulence genes of L. monocytogenes were under-expressed after co-cultivation with B. subtilis at both temperatures while co-cultivation with L. innocua at 37°C, increased the overall gene expression levels of ScottA (e.g. 7-fold increase of prfA).
Significance: Investigating the impact and mechanisms of microbial interactions on growth and virulence of L. monocytogenes expands our understanding on the survival and infection potential of the pathogen in the gastrointestinal environment.
