<jats:title>ABSTRACT</jats:title> <jats:p> Thaxtomin A is the main phytotoxin produced by <jats:italic>Streptomyces scabies</jats:italic> , a causal agent of potato scab. Thaxtomin A is a yellow compound composed of 4-nitroindol-3-yl-containing 2,5-dioxopiperazine. A collection of nonpathogenic streptomycetes isolated from potato tubers and microorganisms recovered from a thaxtomin A solution were examined for the ability to grow in the presence of thaxtomin A as a sole carbon or nitrogen source. Three bacterial isolates and two fungal isolates grew in thaxtomin A-containing media. Growth of these organisms resulted in decreases in the optical densities at 400 nm of culture supernatants and in 10% reductions in the thaxtomin A concentration. The fungal isolates were identified as a <jats:italic>Penicillium</jats:italic> sp. isolate and a <jats:italic>Trichoderma</jats:italic> sp. isolate. One bacterial isolate was associated with the species <jats:italic>Ralstonia pickettii</jats:italic> , and the two other bacterial isolates were identified as <jats:italic>Streptomyces</jats:italic> sp. strains. The sequences of the 16S rRNA genes were determined in order to compare thaxtomin A-utilizing actinomycetes to the pathogenic organism <jats:italic>S. scabies</jats:italic> and other <jats:italic>Streptomyces</jats:italic> species. The nucleotide sequences of the γ variable regions of the 16S ribosomal DNA of both thaxtomin A-utilizing actinomycetes were identical to the sequence of <jats:italic>Streptomyces mirabilis</jats:italic> ATCC 27447. When inoculated onto potato tubers, the three thaxtomin A-utilizing bacteria protected growing plants against common scab, but the fungal isolates did not have any protective effect.