Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184–8588, Japan.
*E-mail: nakai@cc.tuat.ac.jp
Hydrobiologia
This study was done to identify unknown allelochemicals released from Myriophyllum spicatum and to investigate their anticyanobacterial effects. A series of analyses of culture solutions and methanol extracts of M. spicatum using gas chromatograph equipped with a mass selective detector revealed that M. spicatum released fatty acids, specifically, nonanoic, tetradecanoic, hexadecanoic, octadecanoic and octadecenoic acids. Nonanoic, cis-6-octadecenoic, and cis-9-octadecenoic acids significantly inhibited growth of Microcystis aeruginosa, whereas tetradecanoic, hexadecanoic, and octadecanoic acids did not show any effect. When the inhibitory effect of nonanoic acid was compared with those of 4 polyphenols and eugenin, which are anti-cyanobacterial compounds previously reported to be released by M. spicatum, nonanoic acid was found to be the most inhibitory to M. aeruginosa. These results indicate that not only polyphenols and eugenin but also fatty acids such as nonanoic acid must be studied to reveal how M. spicatum exerts its allelopathic effect on M. aeruginosa.
