Preston Manwill, Sourthern Utah University
Life Sciences
Plants produce myriad secondary metabolites (essential oil) that play a role in ecological interactions. Species evolve unique mixtures of organic compounds due to strong selective pressures that act on metabolic pathways. Few studies have investigated the antimicrobial properties of secondary metabolites that evolved against soil microbes associated with native plants. The essential oil of Mojave goldenbush (Ericameria linearifolia), a shrub native to the Intermountain West, was characterized and its bacteriostatic abilities against root associated and non-root associated bacteria morphs were examined in this study. We hypothesized E. linearifolia oil would act as a greater growth inhibitor against native soil bacteria with which it has evolved than against bacteria from non-associated soils. Secondary metabolites were extracted using steam distillation and analyzed with gas chromatography mass spectroscopy. A Kirby-Bauer assay tested presence, size and retention of inhibition zones (IZ) produced against soil bacteria. The essential oil of E. linearifolia contained twenty secondary metabolites, two of which, limonene and sabinene, constituted greater than fifty percent of the oil. Presence and retention of IZ produced by E. linearifolia metabolites varied significantly by community association and bacteria morph. The hypothesis was supported by IZ that were largest against bacteria cultures isolated from soil that surrounded Mojave goldenbush roots and least effective against cultures isolated from non-root associated soil. Our findings suggest that secondary metabolites of E. linearifolia have evolved to specifically prevent negative interactions with bacteria most associated with the plant.