Mechanistic insights into the global response to phenol in the phenol-biodegrading strain Pseudomonas sp. M1 revealed by quantitative proteomics

Quantitative proteomics was used to gain insights into the global adaptive response to phenol in the phenol-biodegrading strain Pseudomonas sp. M1 when an alternative carbon source (pyruvate or succinate) is present. A phylogenetic analysis indicated Pseudomonas citronellolis as the closest species to the environmental strain M1, while P. aeruginosa is the closest species with the genome sequence available. After two-dimensional gel electrophoresis (2-DE) separation, protein identification by MS/MS ion search allowed the assignment of 87 out of 136 selected protein spots, 56 of which matched P. aeruginosa proteins present in databases. Coordinate induction of six enzymes of the phenol catabolic pathway in cells grown in pyruvate and phenol was revealed by expression proteomics. When succinate was the alternative carbon source (C-source), these catabolic proteins were not expressed. The global response of Pseudomonas sp. M1 to phenol-induced stress involved, among others, proteins of the energy metabolism, stress response proteins, and transport proteins. Quantitative and/or qualitative differences were registered in M1 response to different phenol concentrations or to identical phenol concentrations when cells were grown in pyruvate or succinate medium. They were attributed to differences observed in the specific growth rate, in the expression of phenol catabolism, and in resistance to phenol of Pseudomonas sp. M1 grown under different conditions.