SPORE GERMINATION IN PHYCOMYCES-BLAKESLEEANUS

The spores of the Zygomycete Phycomyces blakesleeanus are usually expo sed to heat or acetate to bring nearly all of them to germinate within hours. In the absence of such treatments, about 4% of the spores germ inated each day after being inoculated in a filter-sterilized minimal medium that fully supports growth and differentiation. This rate remai ned constant for many days. The germination rate was higher in autocla ve-sterilized minimal medium. We attribute this activation to the acti on of 5-hydroxymethylfurfural, a decomposition product of glucose heat ed under acidic conditions. Furfural had no effect. Gallic acid, accum ulated and excreted by Phycomyces mycelia in considerable amounts, inh ibited spore germination but not mycelial growth. The inhibition depen ded on the product of the gallic acid concentration and the exposure t ime and disappeared upon washing the spores. Gallic acid prevents spor e germination in environments already colonized by Phycomyces.