The composition of a bioprocessed shiitake mushroom mycelia and rice bran formulation and its antimicrobial effects against Salmonella enterica subsp. enterica serovar Typhimurium strain SL1344 in macrophage cells and in mice

Authors: KIM, SUNG PHIL - Ajou University Of Korea; LEE, SANG JONG - Str Biotech Co Ltd; NAM, SEOK HYUN - Ajou University Of Korea; Friedman, Mendel

Submitted to: BMC Complementary and Alternative Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2018
Publication Date: 12/5/2018
Citation: Kim, S., Lee, S., Nam, S., Friedman, M. 2018. The composition of a bioprocessed shiitake mushroom mycelia and rice bran formulation and its antimicrobial effects against Salmonella enterica subsp. enterica serovar Typhimurium strain SL1344 in macrophage cells and in mice. BMC Complementary and Alternative Medicine. 18:(1)322. https://doi.org/10.1186/s12906-018-2365-8.
DOI: https://doi.org/10.1186/s12906-018-2365-8

Interpretive Summary: Rice plants produce bioactive rice brans and hulls, while mushrooms produce bioactive polysaccharides and other compounds. The main objective of the present study was to elucidate the mechanism that governs the inactivation of foodborne Salmonella Typhimurium pathogenic bacteria in mice by a bioprocessed (fermented) mixture of rice bran added to a Shiitake mushroom mycelia culture. The orally administered extracts of the bioprocessed product inhibited the growth of Salmonella in infected mouse organs (cecum, mesenteric lymph node, spleen, and liver). Detailed efforts using murine macrophage cells to define the biomarkers associated with the possible mechanism of the antibiotic effect indicates that the bactericidal activity in mice is associated with an enhanced autophagic activity leading to systemic bactericidal action. Studies are needed to confirm the health benefits of the new food-based antimicrobial formulation in animal feeds, human foods, and in humans.

Technical Abstract: The present study investigated the antibacterial effect of a bioprocessed (fermented) rice bran extract (BPRBE) from Lentinus edodes liquid mycelia culture against Salmonella Typhimurium SL1344 in vitro and in mice. BPRBE stimulated uptake of the bacteria into RAW 264.7 murine macrophage cells. Activation of the cells was confirmed by increases in NO production resulted from elevation of inducible nitric oxide synthase (iNOS) mRNA and protein expressions. Salmonella infection down-regulated expression of the following protein biomarkers of autophagy (a catabolic process for stress adaptation of cellular components): Beclin-1, Atg5, Atg12, Atg16, LC3-'and LC3-'. BPRBE promoted the upregulation of protein expressions, inducing bacterial destruction in autolysosomes of RAW 264.7 cells. ELISA analysis on IFN-ß showed that inflammatory cytokine secretion and bactericidal activity had similar profiles, suggesting that BPRBE enhanced cell-autonomous and systemic bactericidal activities via autophagic capture of Salmonella. The treatment also elicited increased excretion in feces and decreased translocation of bacteria to internal organs. Although inactive in vitro, the antibiotic mechanism of BPRBE involves phagocytosis of extracellular bacteria, autophagic capture of intracellular bacteria, and prevention of translocation of bacteria across the intestinal epithelial cells. The new bioprocessed rice bran-mushroom mycelia formulation has the potential to serve as a functional antimicrobial food and medical antibiotic.