A novel bacterium has been found that causes a soft rot disease of Agaricus
bisporus, the cultivated mushroom. It has been characterized using nutriti
onal, physiological, chemical and molecular techniques. Based on these data
, it was shown to have many characteristics in common with members of the g
enus Janthinobacterium. Despite similarities to the only described species
within this genus, Janthinobacterium lividum, there were a number of differ
ences between the mushroom pathogen isolated and this species. Despite the
high degree of genotypic similarity between members of the genus Janthinoba
cterium and Herbaspirillum, as evidenced by DNA-RNA hybridization, and the
high degree of 16S rDNA sequence similarity between members of the genera J
anthinobacterium, Herbaspirillum, Oxalobacter and Duganella, as well as the
generically misnamed Pseudomonas lemoignei, it was possible to show that m
embers of the genus lanthinobacterium could be easily distinguished from th
ese taxa. The data also indicated that the mushroom pathogenic strains repr
esent a novel species within the genus lanthinobacterium for which the name
Janthinobacterium agaricidamnosum sp. nov. is proposed. The type strain of
this species has been deposited in the Deutsche Sammlung von Mikroorganism
en und Zellkulturen GmbH, Braunschweig, Germany, as DSM 9628(T) and at the
National Collection of Plant-pathogenic bacteria, UK, as NCPPB 3945(T). To
aid practical control of the disease, the effect of the relative humidity o
n symptom expression on Agaricus bisporus was determined.