NAFTOKINONES AS INHIBITORS OF BIOFILM FORMATION OF A Yersinia enterocolitica REFERENCE STRAIN.

CECILIA LUCERO ESTRADA; NATALIA DI MARCO; CARLOS R. PUNGITORE

Tucumán

Congreso; XII Congreso Argentino de Microbiología General (SAMIGE); 2017

Asociación Civil de Microbiología General

Yersinia enterocolitica is a Gram-negative coccobacillus belonging to Enterobactereaceae family. It ispathogenic to humans and warm-blooded animals. It is frequently isolated from samples of water,animals and a wide variety of foods. The main route of transmission is oral, by ingestion of water orcontaminated food, where it can reach a high concentration, even if these are kept refrigerated. At 25°C it has the ability to form biofilms, which are accumulations of bacterial cells surrounded mainly byhighly hydrated polysaccharides that give the involved bacteria protection against multiple adverseenvironmental conditions. Y. enterocolitica has an intercellular communication system called QuorumSensing (QS), which allows it to communicate with each other through chemical molecules calledN-acyl-homserine lactones, to develop coordinated behaviors depending on cell density, such asbiofilm formation, among others. The naphthoquinones are a chemical compounds group present in agreat variety of plants whereby they are used as base in traditional medicine. It has been shown thatsome representatives of this group of compounds are able to inhibit the biofilms formation of severalbacterial species. The high occurrence of strains resistant to various antimicrobials due to theirindiscriminate use has led to the search for new compounds that inhibit virulence factors such asbiofilm, instead of inhibiting the planktonic growth of cells, which would lead to less resistance, this iswhy the objective of this work was to evaluate the activity of 28 naphthoquinones, obtained bychemical semi-synthesis, in the biofilm development of the reference strain Y. enterocolitica WAPB1B/O:8, that carries the virulence plasmid (pYV+). For biofilm inhibitors screening, the crystal violettechnique with trypticase soy broth supplemented with 0.25% glucose was used followed by thedetermination of the Minimum Inhibitory Concentration of Biofilm (CIMB). Finally, QS was evaluated asa possible biofilm inhibitor mechanism by measuring diameters of violacein halos produced by thebiosensor strain Chromobacterium violaceum 026 when it is in contact with homoserine lactonesfromother bacteria. Of the 28 studied compounds, six were biofilm inhibitors 1, 2, 16, 21, 22, and 23;none of them inhibited planktonic growth. The CIMB was 50 mM for compounds 1, 2 and 16; 25 mM for21 and 22 and 3.05 mM for 23. None of these naphthoquinones showed QS inhibition, indicating thatthey inhibitory effect is carried out by another mechanism of action. These results demonstrate thepotential of naphthoquinones to inhibit the biofilm formation of this important enteropathogenicmicroorganism.