Reutericin 6, a bacteriocin produced by Lactobacillus reuteri LA6 that was
isolated from the faeces of a human infant at 2 months of age, was purified
to homogeneity from broth culture-supernatant by reverse-phase chromatogra
phy. Molecular weight (5652) by mass spectrometry and primary structure of
reutericin 6 were identical to that of gassericin A produced by Lactobacill
us gasseri LA39 which was isolated from the faeces of the same human infant
at 4 months old Reutericin 6 was shown to be a class II and cyclic bacteri
ocin. PCR amplification on the chromosome DNA of L. reuteri LA6 as a templa
te with the primers based on the DNA sequences cloned (gassericin A and aci
docin B from Lactobacillus acidophilus M46) and sequencing revealed that L.
reuteri LA6 has the structural gene for gassericin A with no variations am
ong those primers, These results indicate that a bacteriocin of the same st
ructure has been produced by different lactobacilli species isolated from t
he same infant. (C) 2001 Academic Press.