Since P. stutzeri A1501 was originally isolated from paddy soil and because it contains sets of genes for the β-ketoadipate pathway, it should be able to

utilize aromatic compounds. In our study, we observed that this strain can aerobically degrade benzoate and 4-hydroxybenzoate. As the complete genome of P. stutzeri A1501 was sequenced recently [20], we mapped the genes encoding the peripheral pathways for the catabolism of 4-hydroxybenzoate (pob) and benzoate (ben) in the A1501 chromosome (Figure 1A). In many soil bacteria, these peripheral pathway enzymes channel the individual substrates into one of the two branches of the β-ketoadipate Ibrutinib pathway, namely the catechol and protocatechuate branches. Sequence comparison indicated that A1501 has genes encoding all of the enzymes involved in the two branches of the β-ketoadipate pathway. The catechol (cat genes) and the protocatechuate branches (pca genes) converge at β-ketoadipate enol-lactone. One set of enzymes, which are encoded by

pcaDIJF, completes the conversion of β-ketoadipate enol-lactone to tricarboxylic acid NVP-AUY922 cycle intermediates (Figure 1B). Figure 1 The catechol and protocatechuate branches of the β-ketoadipate pathway and its regulation in P. stutzeri A1501. (A) Localization of the gene clusters involved in degradation of benzoate and 4-hydroxybenzoate on a linear map of the chromosome. (B) Predicted biochemical steps for the catechol and protocatechuate pathways in P. stutzeri A1501. The question mark indicates an unknown mechanism that may be involved in the regulation of cat genes. Inactivation of pcaD is shown by “”× “” and accumulations of the intermediates catechol and cis, cis-muconate in the supernatants of the

pcaD mutant are shown by red vertical arrows. Genes whose expression is under catabolite repression control (Crc) are indicated by “”⊥”". In the A1501 genome, the cat genes are chromosomally ifoxetine linked with the ben genes and form an 11.5 kb supercluster (PST1666-PST1676). The deduced amino acid sequence of BenR in A1501 shows high similarity (61% identity) to the P. fluorescens Pf-5 BenR protein. However, the catR gene, which positively regulates the catBC and catA operons in other strains [12, 25], is absent in A1501 (Figure 2A). Additionally, the pca genes in P. stutzeri A1501 are contiguous, whereas the pca genes are scattered over several portions of the genome in other Pseudomonas species, such as P. entomophila [21], P. aeruginosa [26], P. fluorescens [27]and P. putida [2] (Figure 2B). PcaR is an Icl family protein and has been reported to regulate most of the pca genes in the protocatechuate branch of the β-ketoadipate pathway in P. putida [12, 28, 29]. In contrast to other Pseudomonas strains, pcaR is located immediately upstream of pcaI in A1501 (Figure 2B). The deduced amino acid sequence of A1501 PcaR shows 85% identity to that of P. putida KT2440.