A purple-pigment-producing bean wilt bacterium, Corynebacterium flaccumfaciens var. violaceum, n. var.

Abstract

A phytopathogenic coryneform bacterium was shown to be similar to Corynebacterium flaccumfaciens (yellow wilt) and C. flaccumfaciens var. aurantiacum (orange wilt). The newly described bacterium is provisionally given the nomen Corynebacterium flaccumfaciens var. violaceum n. var. The variety name indicates the extracellular purple pigment, the chief distinguishing characteristic of the organism. The optimal temperature for purple pigment production is 20 C in vitro, whereas infected seed turn purple over a wide range of temperatures. Media requirements were determined for optimal purple pigment production. The DNA base composition as moles % guanine + cytosine (GC), is 70.9 ± 0.8, for C. flaccumfaciens Nebr. 21, C. flaccumfaciens ATCC 6887, C. flaccumfaciens var. aurantiacum 2A, and C. flaccumfaciens var. violaceum CV8. The GC content is greater than that reported for other Corynebacterium species. The current taxonomic status of Corynebacterium and related genera is discussed.