RT Journal Article SR Electronic(1) A1 Braendle, D. H. A1 Gardiner, Beth A1 Szybalski, W.YR 1959 T1 Heterokaryotic Compatibility in Streptomyces JF Microbiology, VO 20 IS 2 SP 442 OP 450 DO https://doi.org/10.1099/00221287-20-2-442 PB Microbiology Society, SN 1465-2080, AB SUMMARY: The compatibility system in Streptomyces fradiae may be characterized as follows. When 108 conidia of each of two freshly isolated auxotrophic mutants are mated on minimal medium, a small number, usually 1 to 10, of ‘primary’ heterokaryotic colonies appear (low-frequency mating, LFM). On the other hand, when ‘secondary parental isolates’ (derived from the conidia produced by ‘primary’ heterokaryons) are mated, the frequency of heterokaryon formation is increased by a factor of several thousand. This high-frequency mating (HFM) is a reasonably stable property, decreasing (or increasing) in a stochastic manner, only after a considerable number of subcultures. A mutational origin is therefore postulated for the HFM and LFM isolates, which must be endowed with variable cultural fitness causing diverse population shifts upon subculture. More effective anastomosis, not increase in residual growth of the ‘secondary parental isolates’, appears to be responsible for HFM. No interspecific crosses were successful, even when an HFM tester stock was used, but heterokaryotic interaction between independently isolated auxotrophic mutants derived from the same line of S. fradiae seemed to increase when an HFM strain was one of the partners., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-20-2-442