A STABLE INHIBITOR OF SPORE GERMINATION PRODUCED BY FUNGI

The level of inhibition of germination of spores added to cell-free culture filtrates of Fusarium oxysporum Schlecht. ex Fr. declines with time. This decline can be accounted for by the decreasing levels of volatile sporostatic factors and a stable vacuolation factor produced by F. oxysporum. After the disappearance of the volatile sporostatic factors, a stable principle is recognised in the culture filtrate by a persistent level of inhibition of spore germination which is not completely alleviated by the addition of nutrients. A stable inhibitor of spore germination has been isolated and characterised as nonanoic acid, and evidence is presented that this compound is widely produced among fungi and can inhibit the germination of spores of many fungal species. The contribution of nonanoic acid to sporostasis in cultures of F. oxysporum is assessed. © 1969 Springer-Verlag.