Degradation of Cinnamic Acid by the Rhizospheric Strain Achromobacter insolitus LCu2

The strain Achromobacter insolitus LCu2 isolated from the roots of alfalfa (Medicago sativa L.) utilized cinnamic acid and its methoxy derivatives (vanillic and ferulic acids) as the sole carbon source. Weak growth was observed with m-coumaric acid, but not on o- or p-coumaric acids. Growth on the cinnamic acid was slow and diauxic. The substrate decreased in the cultivation medium by 53%; the degradation efficiency during 14 days was 30 μg/mg wet weight. Despite the bactericidal effect of cinnamic acid, the culture A. insolitus LCu2 remained viable for a long time. Genomic analysis revealed two gene clusters (hca and mhp) responsible for the dihydroxylation of the phenyl ring (hcaA1A2CDB) and its subsequent cleavage to central metabolic products (mhpACDE), as well as a transcriptional regulator (hcaR) and a putative transporter (hcaT). A putative biochemical pathway for cinnamic acid degradation by the strain A. insolitus LCu2 was predicted using genomic data.