Effects of Fucoidan on the Inhibition of Biofilm Formation of Salmonella enterica Subsp. enterica Serovar Typhimurium on Seafoods and Its Molecular Antibiofilm Mechanisms

Foodborne illnesses, particularly those caused by <i>Salmonella enterica</i> subsp. <i>enterica</i> Serovar <i>Typhimurium</i>, present a significant challenge to public health, especially within the seafood industry due to biofilm formation on foods. This study investigated the antibiofilm potential of fucoidan, a sulfated polysaccharide, against <i>Salmonella enterica</i> subsp. <i>enterica</i> Serovar <i>Typhimurium</i> biofilm on crab and shrimp surfaces. Fucoidan's minimum inhibitory concentration (MIC) was determined to be 150 µg/mL. Sub-MIC (1/8, 1/4, 1/2, and MIC) were evaluated for their impact on inhibition of biofilm formation. Fucoidan treatment resulted in significant, dose-dependent inhibition in biofilm formation, achieving 2.61 log CFU/cm² and 2.45 log CFU/cm² reductions on crab and shrimp surfaces, respectively. FE-SEM analysis confirmed biofilm disruption and cell membrane damage. Real-time PCR showed the downregulation of quorum-sensing (<i>luxS</i>) and virulence (<i>rpoS</i>, <i>avrA</i>, and <i>hilA</i>) genes. These results propose that fucoidan has the ability as a natural antibacterial agent for controlling <i>Salmonella enterica</i> subsp. <i>enterica</i> Serovar <i>Typhimurium</i> biofilms in seafood processing, thereby enhancing food safety and minimizing contamination.