Exploring the antibacterial mechanism and biofilm inhibition of Plantago asiatica L. extract against Bacillus cereus with application in milk

<i>Plantago asiatica</i> L. is an edible and medicinal plant with notable antibacterial activity. However, its antibacterial effects against <i>Bacillus cereus</i> have not yet been investigated. In this study, its extract exhibited a minimum inhibitory concentration (MIC) of 50 μg/mL against <i>B</i>. <i>cereus</i> ATCC 11778 and demonstrated effectiveness against antibiotic-resistant strains. Antibacterial activity, confirmed through growth kinetics and microscopy, was linked to cell membrane damage and disruption of genomic DNA and protein profiles. Beyond planktonic cells, the extract significantly combated biofilms, a key virulence factor, reducing biomass by over 77 % and key matrix components. Transcriptomic analysis provided mechanistic depth, revealing that the extract interfered with central metabolism, virulence, and membrane transport, and downregulated three key biofilm-related genes. This multi-faceted mechanism was validated in a practical food application, where 1 mg/mL of the extract completely inhibited bacterial growth in skim milk within 24 h. This study is the first to comprehensively demonstrate the dual antibacterial and antibiofilm efficacy of <i>P</i>. <i>asiatica</i> L. extract against <i>B</i>. <i>cereus</i>, establishing its potential as a novel, multi-targeted biointervention agent for the food industry.