The effect of prebiotics on production of antimicrobial compounds, resistance to growth at low pH and in the presence of bile, and adhesion of probiotic cells to intestinal mucus
Aims: Screening of five bile salt-resistant and low pH-tolerant lactic acid bacteria for inhibitory activity against lactic acid bacteria and bacterial strains isolated from the faeces of children with HIV/AIDS. Determining the effect of prebiotics and soy milk-base on cell viability and adhesion of cells to intestinal mucus. Methods and Results: Lactobacillus plantarum 423, Lactobacillus casei LHS, Lactobacillus salivarius 241, Lactobacillus curvatus DF 38 and Pediococcus pentosaceus 34 produced the highest level of antimicrobial activity (12 800 AU ml-1) when grown in MRS broth supplemented with 2% (m/v) dextrose. Growth in the presence of Raftilose®Synergy1, Raftilose®L95 and Raftiline®GR did not lead to increased levels of antimicrobial activity. Cells grown in the presence of Raftilose®Synergy1 took longer to adhere to intestinal mucus, whilst cells grown in the absence of prebiotics showed a linear rate of binding. Conclusions: A broad range of gram-positive and gram-negative bacteria were inhibited. Dextrose stimulated the production of antimicrobial compounds. Adhesion to intestinal mucus did not increase with the addition of prebiotics. Significance and Impact of the Study: The strains may be incorporated in food supplements for HIV/AIDS patients suffering from gastro-intestinal disorders. © 2006 The Society for Applied Microbiology.