title: CK3
design: Given P1 strain important ecological role in the degrade of PAHs and with the availability of its full genome sequence, Cycloclasticus may now serve as a model organism to understand bacterial PAHs metabolism. Much more work is needed to understand the pathways that Cycloclasticus uses to catabolize PAH compounds. In addition to determining the metabolic and enzymatic capabilities, a number of specific questions intrinsically linked to PAHs utilization by this important group of PAH degraders, for example how PAHs enter the cell and which transport systems may be involved, how the cells physically interact with the hydrophobic substrate, whether and how they attach to it, and which molecular mechanisms allow the cells chemotactic to PAHs, how these bacteria regulate the pathways that carry out PAH degradation especially when high-molecular weight PAH compounds, etc. To obtain a still more comprehensive picture of PAHs utilization, and in particular to be able to look more closely into some of the aforementioned issues, we have now used RNA-seq technology to compare the transcriptional profile of P1 grown on naphthalene, phenathrene , pyrene, respectively, as a model PAH, as compared with pyruvate, one of the few non PAH substrates Cycloclasticus sp. P1 is able to use.