Brown fruit spot symptoms were observed on yellow Spanish melons (Cucumis m
elo var. inodorus) grown in greenhouses at Almeria in Spain. Nonsporing, mo
tile, rod-shaped bacteria were isolated from diseased fruits, which on nutr
ient agar produced small yellow colonies. Two bacterial isolates, used for
further investigations, were pathogenic on fruits but not on cotyledons of
Spanish melon plants. They provoked disease symptoms similar to those obser
ved in the greenhouse. Both isolates were Gram-negative, catalase-positive,
weakly oxidase-positive and phenylalanine deaminase-negative, They hydroly
sed esculin but not gelatin and they utilized glucose oxidatively. Fatty ac
id analysis revealed that both isolates belong to the genus Sphingomonas. I
n addition, 16S rDNA sequence analysis, performed on one isolate, demonstra
ted that it had a significant sequence similarity (more than 98%) with Sphi
ngomonas pruni and Sphingomonas mall, nonphytopathogenic bacteria isolated
from plants. Although enterobacterial repetitive intergenic consensus PCR a
nd repetitive extragenic palindromic PCR seem to indicate that the Sphingom
onas isolates from Spanish melon fruits may belong to a new species, DNA-DN
A hydridization analysis is necessary to verify this hypothesis.