Self-inhibition of arthrospore germination in Geotrichum candidum

Abstract

An attempt to isolate a self-inhibitor of spore germination in Geotrichum candidum Link was unsuccessful because of the instability of the self-inhibitor. The ability of different carbon sources to stimulate germination and support somatic growth was tested in self-inhibitory conditions. Acetate, fructose, galactose, and glycerol supported both germination and somatic growth. All the fatty acids tested allowed germination but were unable to support vegetative growth; conversely mannitol could not induce germination but did support vegetative growth. Measurements of oxygen uptake by germinating arthrospores at various arthrospore concentrations showed a decrease in oxygen uptake per spore as the spore concentration (= self-inhibitor concentration) increased. Oxygen uptake per spore by dormant arthrospores also decreased with increasing spore concentration. Spore age was another factor influencing oxygen uptake by dormant spores; oxygen uptake per spore decreased with increasing spore age up to 7 days. Continued aging did not decrease the rate of oxygen uptake any further.