PROTEOMIC ANALYSIS OF THE Enterococcus mundtii CRL 35?Escherichia coli O157:H7 INTERACTION DURING ITS GROWTH IN MEAT MEDIUM

ORIHUEL, A; BONACINA, J; VIGNOLO G; SAAVEDRA L; FADDA S

San Miguel de Tucumán

Simposio; International Symposium on Lactic Acid Bacteria; 2016

CERELA_CONICET

Shiga Toxin-producing Escherichia coli (STEC) is one of major concern for the sustainabilityof the meat industry and a serious threat for public health. Many studies allowed to confirmthe role of cattle as the main reservoir of STEC. Enterohemorrhagic E. coli (EHEC) a subgroupwithin the STEC pathotype, is important for its negative impact on public health and associatedwith 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 mostcommon cause of acute renal failure and the second cause of kidney transplantation in childrenand teenagers. For these reasons, and considering the current consumers exigencies forproducts with high standards of hygiene, without chemical additives, biological solutions areurgent. In this context, the use of Lactic Acid Bacteria (LAB) as bioprotective cultures is knownand well documented for certain pathogens. However the efficiency of LAB and its metabolitesto inhibit EHEC has been little explored. In previous studies, E. mundtii CRL35 showedto accelerate the death phase of E. coli O157:H7 NCTC12900 when grown in co-culture in ameat model. Therefore, in order to understand the molecular basis of this interaction, theobjective of this study was to evaluate the differential protein expression of both speciesduring their growth in co-culture, using two-dimensional electrophoresis. The analysis wascarried 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 CRL35persistedin steady state. One hundred nine spots showed statistically significant difference (> 1.1 foldchange) in their expression level. Those proteins showing differences higher than 2 fold weresubjected to MALDI TOF-MSMS analysis (44 spots). Twenty two spots were successfully identified.The identified proteins corresponded to both microorganisms and belonged to variousfunctional groups. Differential protein expression was related to behavior and growth state ofeach microorganism. In fact, those proteins differentially expressed at 6 h, during the exponentialgrowth, belonged to carbohydrates metabolism, such as glucose-6-phosphate isomerase,phosphopyruvate hydratase or transketolase and corresponded to E. mundtii CRL35indicating more active energy metabolism than E. coli O157:H7 during similar growth state(6 h). On the other hand, proteins overexpressed at 30 h, were mainly from E. coli O157:H7,and related to stress conditions (glutamate decarboxylase and catalase HPI) according tothe death phase spanning the pathogen at 30 h. Additional proteomic assays are ongoing todeepen in BAL-EHEC interaction.