LAMVAB - A NEW SELECTIVE MEDIUM FOR THE ISOLATION OF LACTOBACILLI FROM FECES

The development of a new selective medium, LAMVAB, for the isolation o f Lactobacillus species from faeces is described. The medium is highly selective due to a low pH and the presence of vancomycin (20 mg l(-1) ). In addition, the medium contains cysteine-HCl to enhance anaerobic conditions, and bromocresol green as a pH indicator. Competing faecal flora is inhibited by the low pH (enterobacteria, bacteroides and othe r Gram-negative anaerobes, clostridia) and the vancomycin (enterococci , bifidobacteria, clostridia). Characterization of the strains isolate d on LAMVAB from human faeces included all common faecal lactobacilli and no other lactic acid bacteria. In one sample, vancomycin-resistant cocci were present and in another sample, yeasts were isolated. It ca n be concluded that the new medium is highly selective and permits the growth of all common faecal lactobacilli. The new medium can also be appl:ed as a selective medium for lactobacilli in probiotics, which co ntain mixed populations of lactobacilli, bifidobacteria and enterococc i. (C) 1997 Elsevier Science B.V.