Effect of the Cyanobacterial Metabolite Geosmin on Growth of a Green Alga

Geosmin (trans-1,10-dimethyl-trans-decalol) is an odorous compound produced by some species of cyanobacteria. It was found to enhance the growth of Selenastrum 1648, a green alga. Chlorophyll a concentrations of unialgal Selenastrum cultures differed significantly in cultures (p<0.001) with different geosmin concentrations. Chlorophyll a concentrations were highest in flasks with geosmin concentrations of 480 ng/l, and lowest in flasks to which no geosmin was added. Significantly higher chlorophyll a concentrations in flasks with higher geosmin concentrations indicate that geosmin may be functioning as some kind of growth enhancer or antibiotic, possibly reducing populations of parasitic bacteria or fungi that antagonize algae.