Resveratrol as a growth substrate for bacteria from the rhizosphere.

Resveratrol is among the best-known secondary plant metabolites because of its antioxidant, anti-inflammatory and anticancer properties. It also is an important allelopathic chemical widely credited with protection of plants from pathogens. The ecological role of resveratrol in natural habitats is difficult to establish rigorously because it does not seem to accumulate outside of plant tissue. It is likely that bacterial degradation plays a key role in determining the persistence, and thus the ecological role, of resveratrol in soil. Here we report the isolation of an Acinetobacter species that can use resveratrol as a sole carbon source from the rhizosphere of peanut plants. Both molecular and biochemical techniques indicate that the pathway starts with the conversion of resveratrol to 3,5-dihydroxybenzaldehyde and 4-hydroxybenzaldehyde. The aldehydes are oxidized to substituted benzoates that subsequently enter central metabolism. The gene that encodes the enzyme responsible for the oxidative cleavage of resveratrol was cloned, and expressed in E. coli to establish its function. Its physiological role in the resveratrol catabolic pathway was established by knockouts and by RT-qPCR demonstration of expression during growth on resveratrol. The results establish the presence and capabilities of resveratrol degrading bacteria in the rhizosphere of the peanut plants and set the stage for studies to evaluate the role of the bacteria in plant allelopathy.IMPORTANCE In addition to its antioxidant properties, resveratrol is an example of a broad array of allelopathic chemicals produced by plants to inhibit competitors, herbivores and pathogens. Bacterial degradation of such chemicals in the rhizosphere would reduce the effects of the chemicals. Therefore, it is important to understand the activity and ecological role of bacteria that biodegrade resveratrol near the plants that produce it. This study describes the isolation from the peanut rhizosphere of bacteria that can grow on resveratrol. Characterization of the initial steps in the biodegradation sets the stage for investigation of the evolution of the catabolic pathways responsible for biodegradation of resveratrol and its homologs.