The distribution of DNA sequences hybridizing with antibiotic production and resistance gene probes within type strains and wild isolates of Streptomyces species.

Total DNA preparations from 74 antibiotic-producing type strains and 102 natural Streptomyces isolates were examined by dot blots for homology to 6 antibiotic production and resistance genes. Pattern diversity of hybridizations decreased as stringency increased from 65% to 85%. There were 146 unique profiles at 65% stringency with 13 repeated patterns, whilst there were only 14 unique and 11 repeated profiles at 85% stringency. Most of the strains which hybridized at 85% reacted with one or two probes although a few strains showed multiple homologies. This data was used to cluster strains and the groups defined were examined for phenotypic antibiotic resistance. Producers of certain classes of antibiotics clustered to specific groups and some gene homologies were more common amongst strains which produced similar antibiotics.