초록
<P>Rhamnolipid biosurfactants have potential applications in the control of zoosporic plant pathogens. However, rhamnolipids have not been closely investigated for the anti-zoospore mechanism or for developing new anti-zoospore chemicals. In this study, RhL-1 and RhL-3 groups of rhamnolipids were used to generate the corresponding RhL-2 and RhL-4 groups and the free diacids. Conversion of RhL-3 to RhL-1 was also accomplished <I>in vitro</I> with cellobiase as the catalyst. The anti-zoospore effects of RhL-1–RhL-4 and the diacids were investigated with zoospores of <I>Phytophthora sojae</I>. For RhL-1–RhL-4, approximately 20, 30, 40, and 40 mg/L, respectively, were found to be the lowest concentrations required to stop movement of all zoospores, which indicates that the anti-zoospore effect remains strong even after RhL-1 and RhL-3 are hydrolyzed into RhL-2 and RhL-4. The free diacids required a significantly higher critical concentration of about 125 mg/L. Rhamnose can be obtained as a co-product.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2015/jafcau.2015.63.issue-13/acs.jafc.5b00033/production/images/medium/jf-2015-00033h_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf5b00033'>ACS Electronic Supporting Info</A></P>