General Features 355 Cell Wall 357 Genomes 359 Transcriptional Regulators 361 Posttranscriptional Regulation 364 Plasmids and Transposon Use 364 Conclusion 367 References 367Corynebacterium was originally dened in 1896 by Lehmann and Neumann to accommodate nonmotile parasitic and pathogenic bacteria, including diphtheroid bacilli [1]. Diphther is the Greek word for “membrane” and describes the fact that these latter bacteria can typically be isolated from a false membrane in the pharynx developed due to the necrotic action of the toxin made by Corynebacterium diphtheriae. Before the establishment of modern systematics, the taxon Corynebacterium accommodated a number of heterogeneous bacteria. However, based on the extended use of chemotaxonomic markers, mainly in the last third of the past century, like cell wall chemistry, lipid composition and DNA base composition, the taxon Corynebacterium was brought into sharper focus and it also was recognized that it is a member of the so-called CMN-group of bacteria including, in addition to Corynebacterium, also Mycobacterium and Nocardia. It is now clear that based on 16S rRNA/rDNA sequence patterns, Corynebacterium forms a robust and well-dened monophyletic group that together with Dietzia, Gordonia, Mycobacterium, Nocardia, Rhodococcus, Skermania, Tsukamurella, and Williamsia, forms the suborder Corynebacterineae belonging to the order Actinomycetales [2]. Recent reviews covering several aspects of pathogenic and nonpathogenic Corynebacterium species are available [3-6].