Proteomic Analysis of the Enterococcus mundtii CRL 35 ? Escherichia coli O157:H7 Interaction during Its Growth in Meat Medium

ORIHUEL, A; SAAVEDRA L; FADDA S

San Miguel de Tucuman

Simposio; V Simposio Internacional de Bacterias Lácticas-SIBAL CERELA- CONICET; 2016

CERELA CONICET

Shiga Toxin-producing Escherichia coli (STEC) is of major concern for the sustainability of the meat industry and a serious threat for public health. Many studies allowed to confirm the role of cattle as the main reservoir of STEC. Enterohemorrhagic E. coli (EHEC) a subgroup within the STEC pathotype, is important for its impact on public health and associated with severe disease in humans. E. coli O157:H7 is the prototype of this bacterial group. In Argentina, the hemolytic uremic syndrome, mainly caused by EHEC, constitutes the most common cause of acute renal failure and the second cause of kidney transplantation in children and teenagers. For these reasons, and considering the current consumers exigencies for products with high standards of hygiene, without chemical additives, biological solutions are urgent. In this context, the use of Lactic Acid Bacteria (LAB) as bioprotective cultures is known and well documented for certain pathogens. However the efficiency of LAB and its metabolites to inhibit EHEC has been little explored. In previous studies, E. mundtii CRL35 showed to accelerate the death phase of E. coli O157:H7 NTCC12900 when grown in co-culture in a meat model. Therefore, in order to understand the molecular basis of this interaction, the objective of this study was to evaluate the differential protein expression of both species during their growth in co-culture, using two-dimensional electrophoresis. The analysis was carried out at two specific times of growth: 6 h, when both microorganisms grew exponentially, and 30 h, when the pathogen reached its death phase while E. mundtii CRL35 persisted in steady state. One hundred nine spots showed statistically significant difference (> 1.1) in their expression level. Those proteins showing differences higher than 2 fold were subjected to MALDI TOF-MS MS analysis (44 spots). Twenty two spots were successfully identified. The identified proteins corresponded to both microorganisms and belonged to various functional groups. Differential protein expression was related to behavior and growth state of each microorganism. In fact, those proteins differentially expressed at 6 h, during the exponential growth, belonged to carbohydrates metabolism, such as glucose-6-phosphate isomerase, phosphopyruvate hydratase or transketolase and corresponded to E. mundtii CRL35 indicating more active energy metabolism than E. coli O157:H7 during similar growth state (6 h). On the other hand, proteins over expressed at 30 h, were mainly from E. coli O157:H7, and related to stress conditions (glutamate decarboxylase and catalase HPI) according to the death phase spanning the pathogen at 30 h. Additional proteomic assays are ongoing to deepen in BAL-EHEC interaction.