The Streptomyces strain Streptomyces anulatus JH801 showed submerged sporulation and production of a genotoxic activity. The genotoxin production of this strain was found to be correlated to morphology and is likely to be related to sporulation. The influence of the medium on genotoxin production was investigated. Genotoxin production and sporulation were not inhibited by glucose, but were negatively affected by low ammonia concentrations. No correlation was found between genotoxin production and other morphological parameters such as total hyphal length and total average tip number. Bioassay‐directed fractionation of the chloroform extract of S. anulatus JH801 resulted in the isolation of dihydroabikoviromycin. This compound shows selective activity towards DNA repair‐deficient Escherichia coli. The isolation and structure of this genotoxin are reported.