Naftokinones as inhibitors of biofilm formation of a Yersinia enterocolitica reference strain.

DI MARCO, NATALIA; CARLOS RODOLFO PUNGITORE; LUCERO ESTRADA CECILIA STELLA MARYS

San Miguel de Tucumán

Congreso; XII Congreso Argentino de Microbiología General.; 2017

Sociedad Argentina de Microbiología General

Yersinia enterocolitica is a Gram-negative coccobacillus belonging to Enterobactereaceae family. It is pathogenic 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 or contaminated food, where it can reach a high concentration, even ifthese are kept refrigerated. At 25 °C it has the ability to form biofilms, which are accumulations of bacterial cells surrounded mainly by highly hydrated polysaccharides that give the involved bacteria protection against multiple adverse environmental conditions. Y. enterocolitica has an intercellular communication system called Quorum Sensing (QS), which allows it to communicate with each other through chemical molecules called N-acyl-homserine lactones, to develop coordinated behaviors depending on cell density, such as biofilm formation, among others. The naphthoquinones are a chemical compounds group present in a great variety of plants whereby they are used as base in traditional medicine. It has been shown that some representatives of this group of compounds are able to inhibit the biofilms formation of several bacterial species. The high occurrence of strains resistant to various antimicrobials due to their indiscriminate use has led to the search for new compounds that inhibit virulence factors such as biofilm, instead of inhibiting the planktonic growth of cells, which would lead to less resistance, this is why the objective of this work was to evaluate the activity of 28 naphthoquinones, obtained by chemical semi-synthesis, in the biofilm development of the reference strain Y. enterocolitica WAP B1B/O:8, that carries the virulence plasmid (pYV+). For biofilm inhibitors screening, the crystal violet technique with trypticase soy broth supplemented with 0.25% glucose was used followed by the determination of the Minimum Inhibitory Concentration of Biofilm (CIMB). Finally, QS was evaluated as a possible biofilm inhibitor mechanism by measuring diameters of violacein halos produced by the biosensor strain Chromobacterium violaceum 026 when it is in contact with homoserine lactones From other 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 for 21 and 22 and 3.05 mM for 23. None of these naphthoquinones showed QS inhibition, indicating that they inhibitory effect is carried out by another mechanism of action. These results demonstrate the potential of naphthoquinones to inhibit the biofilm formation of this important enteropathogenic microorganism.