Assimilation of aromatic compounds by Comamonas testosteroni: characterization and spreadability of protocatechuate 4,5-cleavage pathway in bacteria

Appl Microbiol Biotechnol. 2013 Jul;97(13):6031-41. doi: 10.1007/s00253-012-4402-8. Epub 2012 Sep 21.


Comamonas testosteroni strain CNB-1 was isolated from activated sludge and has been investigated for its ability to degrade 4-chloronitrobenzene. Results from this study showed that strain CNB-1 grew on phenol, gentisate, vanillate, 3-hydroxybenzoate (3HB), and 4-hydroxybenzoate (4HB) as carbon and energy sources. Proteomic data and enzyme activity assays suggested that vanillate, 3HB, and 4HB were degraded in strain CNB-1 via protocatechuate (PCA) 4,5-cleavage pathway. The genetics and biochemistry of the PCA 4,5-cleavage pathway were investigated. Results showed that the 4-oxalomesaconate (OMA) hydratase from C. testosteroni takes only enol-OMA as substrate. A previously functionally unknown gene pmdU encodes an OMA tautomerase and catalyzes conversion of OMAketo into OMAenol. The 4-carboxy-4-hydroxy-2-oxoadipate (CHA) aldolase is encoded by pmdF and catalyzes the last step of the PCA 4,5-cleavage pathway. We explored the 1,183 microbial genomes at GenBank for potential PCA 4,5-cleavage pathways, and 33 putative pmd clusters were found. Results suggest that PCA 4,5-cleavage pathways are mainly distributed in α- and β-Proteobacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biotransformation
  • Comamonas testosteroni / genetics
  • Comamonas testosteroni / metabolism*
  • Computational Biology
  • Genome, Bacterial
  • Hydrocarbons, Aromatic / metabolism*
  • Hydroxybenzoates / metabolism*
  • Metabolic Networks and Pathways / genetics*


  • Hydrocarbons, Aromatic
  • Hydroxybenzoates
  • protocatechuic acid