Die Mureintypen in der Gattung Microbacterium

The quantitative amino acid composition of the murein of M. flavum, M. thermosphactum, M. lacticum and M. liquefaciens was determined. The murein of M. flavum and M. thermosphactum contains DAP, Blu and Ala at a molar ratio of about 1:1:1,5-1,7. In addition, 1,8 moles of ammonia were found per mole of glutamic acid, indicating, that both DAP and Glu are present as amides. The murein of M. lacticum and M. liquefaciens showed the following molar ratios. M. lacticum: Hyg¹+Glu:Gly:L-Lys:D-Ala=1:2:2:1; M. liquefaciens: Hyg+Glu:Gly:Hsr: D-Orn:D-Ala=1:2:1:1:1. The amino acid sequence of the murein of M. liquefaciens was determined by analysing the various peptides from acid partial hydrolysates of the cell walls. The murein of M. liquefaciens resembles the murein of M. lacticum. The tetrapeptide bound to the muramic acid has the sequence: Gly-Hyg(Glu)-Hsr-D-Ala. The cross-linkage is performed in the same way as in M. lacticum. The interpeptide bridge N^δ-Gly-D-Orn is bound by its glycine end to the α-carboxyl group of Hyg(Glu) and by the α-amino group of D-Orn to D-Ala of an adjacent peptide subunit. The primary structure of the murein of M. flavum and M. thermosphactum is similar to that of the murein of Corynebacterium diphtheriae as has been shown by the quantitative amino acid composition and the fingerprints of the partial hydrolysates of the cell walls. M. flavum and M. thermosphactum can be distinguished from M. lacticum and M. liquefaciens not only by murein type but also in morphology and certain physiological characteristics. They are closely related to the human and animal pathogenic corynebacteria and should be removed from the genus Microbacterium. M. lacticum and M. liquefaciens, on the other hand, differ significantly from human and animal pathogenic corynebacteria and show greatest similarity to certain plant pathogenic corynebacteria.