Abstract
The guanine plus cytosine (GC) contents of a collection of phytopathogenic coryneform bacteria, determined by buoyant density equilibrium centrifugation in CsCl gradients, fall in the range of about 65 to 73%. By means of DNA-DNA segmental homology determinations, it was possible to show that Corynebacterium fascians is not related genetically to any of the other phytopathogenic coryneforms. A minor partial homology groups (but not very firmly) Corynebacterium insidiosum, C. michiganense, and C. sepedonicum into one genetic cluster and C. poinsettiae, C. betae, C. flaccumfaciens, and C. ilicis into another; these genetic groupings coincide somewhat with others based on serology, morphology, and cell wall composition.
