Mutants of Myxococcus xanthus insensitive to glycerol-induced myxospore formation

Mutants of Myxococcus xanthus FB_t unable to form myxospores in response to 0.5 M glycerol arise spontaneously with a frequency of 1–3×10^–5. These mutants are designated glc. Ultraviolet mutagenesis increases the frequency to a maximum of 7% of the survivors. The reversion frequency following ultraviolet irradiation of spontaneous glc mutants is less than 10^–3. Of four glc mutants examined, none form myxospores in response to the alternative inducers, ethylene glycol and dimethyl sulphoxide. One glc mutant is induced by 1.5 M glycerol; strain FB_t responds to this glycerol concentration with low efficiency myxospore formation. Strain FB_t and glc mutants all produce myxospores with low efficiency in response to phenyl ethanol. Of 117 glc mutants tested, 109 form fruiting bodies containing mature myxospores; thus, mutations to the glc phenotype do not normally block myxospore formation within the fruiting cycle of the organism.