Mutacin H-29B is identical to mutacin II (J-T8)

Mutacin H-29B, produced by S. mutans strain 29B, was purified by successive hydrophobic chromatography from a liquid preparation consisting of cheese whey permeate (6% w/v) supplemented with yeast extract (2%) and CaCO3 (1%). Edman degradation revealed 24 amino acids identical to those of mutacin II (also known as J-T8). The molecular mass of the purified peptide was evaluated at 3246.08 ± 0.1 Da by MALDI-TOF MS.A simple procedure for production and purification of mutacins along with its characterization is presented. Our results show that the amino acid sequence of mutacin H-29B is identical to the already known mutacin II (J-T8) over the first 24 residues. S. mutans strains of widely different origins may thus produce very similar bacteriocins.Bacteriocins are ribosomally synthesised proteinaceous bactericidal substances produced by bacteria [1]. Mutacins are bacteriocins produced by Streptococcus mutans [2] that are active against Gram-positive and some Gram-negative bacteria [3,4]. To date, four types of mutacin have been described: the mono- or di-peptide lantibiotic and the mono- or di-peptide non-lantibiotic mutacin [5-8]. Lantibiotics contain unusual amino acids such as Lan, BM-Lan and dehydrated amino acid residues [9]. Posttranslational modification of the prepeptide occurs through amino acid dehydration, formation of thioether bridges and cleavage of the leader peptide during transport outside of the cell [9].We previously classified mutacin-producing strains into 24 groups (designated A to X) and 7 clusters according to their activity spectra against bacterial pathogens and their immunity towards other mutacins [10,4]. The strain 29B producing mutacin H-29B was found to be closely related in its activity spectrum with strain T8 which produces mutacin II (also known as J-T8) [4]. The DNA probe designed to hybridize with the mutA gene of mutacin II (J-T8) also hybridised with the DNA of strain 29B [11]. We present here a simple procedure for production an