Dissecting the Phenotypic Complexity of Biofilm Development and Quorum Sensing in Salmonella enterica Serovars

This study investigates the mechanisms of biofilm formation and quorum sensing in Salmonella enterica serovars, with particular emphasis on their implications for clinical safety and public health. The ability of this bacterium to form biofilms on various surfaces poses significant challenges for control and eradication efforts, contributing to persistent infections and enhanced antimicrobial resistance. The study explores quorum quenching strategies to inhibit biofilm formation through certain treatments. The research employes crystal violet staining, bacterial growth curve analysis, and fluorescence microscopy to evaluate the effects of quorum sensing (QS) and natural product-based quorum quenching strategies on biofilm formation on abiotic (polystyrene) surfaces. Short- to medium-chain acyl-homoserine lactones (AHLs), particularly C8-HSL were assessed for their role in promoting biofilm development, alongside plant-derived and dietary natural products with reported antimicrobial activity, including aloe emodin (from Aloe vera ), epigallocatechin gallate (EGCG) (from green tea, Camellia sinensis ), thymoquinone from ( Nigella sativa) garlic extract (active compound Allium sativum ), and turmeric extract (active extract Curcuma longa ). Results demonstrated that C8-HSL significantly enhanced biofilm formation (Figs. 2–4; Tables 1–2), with 0.2 mM identified as the most effective concentration (Fig. 4). In contrast, the tested natural products exhibited quorum quenching and anti-biofilm activity, significantly reducing biofilm biomass and structural integrity (Figs. 5 and 6). Fluorescence microscopy further supported these findings by demonstrating enhanced biofilm formation in the presence of quorum sensing molecules and disrupted biofilm architecture following quorum quenching treatment (Figs. 7 and 8). These findings highlight the central role of quorum sensing in Salmonella enterica pathogenicity and demonstrate the potential of plant-derived and dietary natural products as alternative quorum quenching agents for biofilm control. The study suggests that further research, including the use of genetically engineered mutants, is required to elucidate the specific genetic pathways involved in QS-mediated biofilm regulation. Overall, this research advances understanding of biofilm formation and quorum sensing in Salmonella enterica and supports the development of novel strategies to manage persistent infections and improve food safety.