Deoxynucleosides as promising antimicrobial agents against foodborne pathogens and their applications in food and contact material surfaces

<i>V. parahaemolyticus</i> biofilms accumulate on various seafoods and contact surfaces where they induce cross-contamination, spoilage and persistence in the food industry. Recently, nucleosides are being repurposed for antibacterial and technological applications including preservation and flavor enhancement. Therefore, for the first time, we explored the effects of various nucleosides against the biofilm and planktonic lifestyles of <i>Vibrio</i> spp, vis-à-vis the mechanisms, synergism with food additive, food and surface decontamination potentials. Among the sixty-six nucleosides evaluated, 2',3'-dideoxyadenosine (ddA) and 2'-deoxy-5-fluorocytidine (FdCyd) were identified as exceptional biofilm inhibitors, achieving 98 and 100 % reduction respectively. FdCyd exhibited low minimum inhibitory concentration (MIC) of 30, 40 and 10 μg/mL against <i>V. parahaemolyticus</i>, <i>V. harveyi</i> and <i>Salmonella typhimurium</i> while ddA had MICs 40, 40 and >500 μg/mL, respectively. Also, the nucleosides disrupted <i>Vibrio</i> biofilm architecture and caused loss of cell membrane integrity mediated by oxidative stress. Their combinations with sodium tripolyphosphate, a known food additive enhanced antimicrobial activities against <i>V. parahaemolyticus</i> by 4-16-folds. While FdCyd significantly inhibited mixed-biofilm formation of <i>Vibrio</i> and <i>Salmonella</i>, both nucleosides eradicated pre-formed biofilms from food contact surfaces, and showed preservative potentials in squid. Notably, they downregulated genes encoding biofilms and quorum sensing (<i>aphA</i>, <i>cpsA</i>, <i>luxS</i> & <i>opaR</i>), outer membrane (<i>tolC</i>), response regulators (<i>toxR</i>, <i>rpoS</i>) and DNA synthesis (<i>dnaE</i>) as revealed by transcriptomic studies. These results demonstrate that nucleosides, especially FdCyd are promising novel compounds for controlling biofilm formation, maintaining hygiene and safety in food industry.