| Summary: | Integrative and conjugative elements (ICEs) are chromosomally integrated self-transmissible mobile genetic elements. Although some ICEs are known to carry genes for the degradation of aromatic compounds, information on their genetic features is limited. We identified a new member of the ICE<i>clc</i> family carrying biphenyl catabolic <i>bph</i> genes and salicylic acid catabolic <i>sal</i> genes from the PCB-degrading strain <i>Pseudomonas stutzeri</i> KF716. The 117-kb ICE<i><sub>bph-sal</sub></i>KF716 contains common core regions exhibiting homology with those of degradative ICE<i>clc</i> from <i>P. knackmussii</i> B13 and ICE<i><sub>XTD</sub></i> from <i>Azoarcus</i> sp. CIB. A comparison of the gene loci collected from the public database revealed that several putative ICEs from <i>P. putida</i> B6-2<i>, P, alcaliphila</i> JAB1, <i>P. stutzeri</i> AN10<i>,</i> and <i>P. stutzeri</i> 2A20 had highly conserved core regions with those of ICE<i><sub>bph-sal</sub></i>KF716, along with the variable region that encodes the catabolic genes for biphenyl, naphthalene, toluene, or phenol. These data indicate that this type of ICE subfamily is ubiquitously distributed within aromatic compound-degrading bacteria. ICE<i><sub>bph-sal</sub></i>KF716 was transferred from <i>P. stutzeri</i> KF716 to <i>P. aeruginosa</i> PAO1 via a circular extrachromosomal intermediate form. In this study, we describe the structure and genetic features of ICE<i><sub>bph-sal</sub></i>KF716 compared to other catabolic ICEs.
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