Surfactin from Bacillus subtilis enhances immune response and contributes to the maintenance of intestinal microbial homeostasis.

UNLABELLED: Surfactin, a lipopeptide biosurfactant produced by Bacillus spp., has emerged as a promising bioactive compound due to its potent inhibitory effects on bacterial and viral pathogens. This showcases its potential as a non-antibiotic strategy for managing infectious diseases. Our investigation reveals that surfactin administration significantly promotes weight gain and improves immune organ indices in mice, reflecting enhanced immunity and gut health. Surfactin augments phagocytic function in peritoneal macrophages and boosts proliferative responses in splenic lymphocytes post-chicken red blood cell immunization. Furthermore, it increases intestinal villi height, indicative of superior nutrient absorption. It elevates mucin secretion and expression of intestinal mucosal proteins, such as secretory IgA, Muc1, and Muc2, and tight junction proteins claudin-1, occludin, and Zo-1 in the jejunum and colon. Crucially, surfactin modifies the gut microbiota composition by reducing Escherichia coli populations and ameliorating cyclophosphamide-induced gut dysbiosis. Our data suggest that oral surfactin could be a valuable therapeutic modality to alleviate immune suppression and gut damage, proposing a new pathway for immunomodulatory treatment.

IMPORTANCE

The potential of surfactin as a microbial surfactant extends beyond its surfactant properties, impacting immune regulation and gut health. As the need for alternatives to traditional antibiotics continues to grow, surfactin's ability to enhance host defense mechanisms against common pathogens without directly targeting them with antibiotics offers a strategic advantage. Understanding how surfactin shapes the immune landscape and the gut microbiome can inform innovative interventions against immunosuppression and intestinal impairment, particularly in contexts such as cyclophosphamide-induced toxicity.