J. Am. Chem. Soc. 133, 18343–18349 (2011)

Small molecules often define the interactions between bacteria and other species. Seyedsayamdost et al. had previously identified the chemical components of a marine parasitic interaction, in which the microalga Emiliania huxleyi releases a lignin component—p-coumaric acid—into the environment, and the α-proteobacterium Phaeobacter gallaeciensis BS107 responds by producing two toxic roseobacticides. To explore the generality of this phenomenon, the authors tested the impact of p-coumaric acid along with four additional lignin components and related biosynthetic intermediates on roseobacticide production by P. gallaeciensis BS107. Four of the five lignin molecules elicited a chemical response, the components of which could be grouped into four families of roseobacticide analogs, including phenyl-, phenol- and indole-modified structures as well as two dimeric roseobacticides. The authors further observed that treatment with each of the four E. huxleyi elicitors yielded different combinations of the roseobacticides in different proportions. Extension of these tests to additional species identified P. gallaeciensis 2.10 as similarly responsive to the lignin elicitors with additional diversity in roseobacticide production: for P. gallaeciensis BS107, p-coumaric acid and sinapic acid yielded the strongest responses, whereas for P. gallaeciensis 2.10, ferulic acid and cinnamic acid were favored. These results help to define a parasitic system and stimulate further questions regarding the role of the individual roseobacticides.