Characterization of methanol extraction residue (MER) from Bacillus Calmette-Guérin (BCG)

Analysis of methanol extraction residue (MER) from Bacillus Calmette-Guerin (BCG) was carried out to determine some specific chemical compositional characteristics. Samples of MER were found to contain approximately 40% protein and/or peptide, 3% soluble lipids, 17% bound lipids, 8% elemental nitrogen, and less than 2% mycolic acids. Amino acid analysis showed the presence of alanine, glycine and glutamic acid as the major amino acids. The data are reported in terms of the range found for each constituent over the samples analyzed. Somewhat consistent results were obtained between different MER preparations, but notable compositional variations were observed in samples of MER suspensions.