Corynebacterium

The coryneform bacteria are a broad group of gram-positive, irregularly shaped rods (sometime oval-or club-shaped), aerobic or facultatively anaerobic, asporogenous, and nonpartially-acid-fast microorganisms classically used in the production of primary metabolites (amino acids, nucleotides, vitamins, etc.).1 The genus Corynebacterium was created in 1896 in order to assign a classiŠcation to Corynebacterium diphtheriae (the diphtheroid bacilli), as well as several animal pathogens and parasitic microorganisms.2 During most of the twentieth century, many microorganisms were included in this group based on their staining, morphological, and metabolic properties; in fact, in Bergey’s Manual of Determinative Bacteriology, the coryneform group comprised a broad and diverse number of bacteria of medical

(saprophytic animal and human pathogens), agricultural (plant pathogens), and industrial (saprophytic nonpathogenic amino-acid-producing strains) interest. In the 1990s, phylogenetic (based on 16S and 23S rDNA sequence analyses) and chemotaxonomic (cell wall composition and lipid proŠles) analyses resulted in the separation of some members of the coryneform group from those corresponding to plant pathogens.3 Nonetheless, the number of species described for the genus Corynebacterium expanded, from 17 in the Šrst edition of Bergey’s Manual of Systematic Bacteriology4 to more than 70 in the second edition (https://www.bergeys.org/). This large expansion of a bacterial genus is a rare occurrence in microbiology and re³ects the enormous interest in these bacteria, mainly in medicine but also by industry. While very few data are available concerning the numbers of corynebacterial species present in nature, given what is known thus far about the genus Corynebacterium, it can be reasonably assumed

6.1 Introduction ....................................................................................................................................................................... 59 6.1.1 ClassiŠcation, Morphology, and Biology .............................................................................................................. 59 6.1.2 Phenotypic and Phylogenetic Characterization ..................................................................................................... 60

6.1.2.1 Phenotypic Analysis................................................................................................................................ 60 6.1.2.2 Protein Analysis ...................................................................................................................................... 60 6.1.2.3 Phylogenetic Analysis ............................................................................................................................. 64

6.1.3 Pathogenesis and Diagnosis ................................................................................................................................... 65 6.1.3.1 Corynebacterium Diphtheriae ............................................................................................................... 65 6.1.3.2 Corynebacterium Species of the Lipophilic Group ................................................................................ 66 6.1.3.3 Corynebacterium Species of the Nonlipophilic Group .......................................................................... 67

6.2 Methods ............................................................................................................................................................................. 68 6.2.1 Sample Preparation ................................................................................................................................................ 68

6.2.1.1 Culture Media for Corynebacterium ...................................................................................................... 68 6.2.1.2 DNA Isolation ......................................................................................................................................... 68 6.2.1.3 RNA Isolation ......................................................................................................................................... 69

6.2.2 Detection Procedures ............................................................................................................................................. 69 6.2.2.1 Biolog (GP2) System ............................................................................................................................... 69 6.2.2.2 API Coryne System ................................................................................................................................ 69 6.2.2.3 IdentiŠcations Based on 16S rRNAs Genes............................................................................................ 70

6.3 Future Perspectives and Conclusions................................................................................................................................. 70 Acknowledgments ....................................................................................................................................................................... 71 References ................................................................................................................................................................................... 71

that corynebacteria are abundantly disseminated within a broad range of different natural habitats. In turn, much species diversity remains to be identiŠed and characterized.