Phylogeny of Streptomyces species and evidence for horizontal transfer of entire and partial antibiotic gene clusters

The phylogenetic relationships of a collection of streptomycete soil isolat es and type strains were resolved by sequence analysis of trpB, a housekeep ing gene involved in tryptophan biosynthesis. The analysis confirmed that t wo isolates were recipients in a gene transfer event, demonstrated by phylo genetic incongruency between trpB and strB1 trees. One strain had acquired the entire streptomycin biosynthetic cluster, whilst the other contained on ly strRAB1, the resistance gene and two flanking genes from the cluster. Se quence analysis of trpB, as part of a polyphasic approach, was a useful too l in determining intra-generic relationships within the genus Streptomyces.