Novel organization of aromatic degradation pathway genes in a microbial community as revealed by metagenomic analysis

Hikaru Suenaga, Yoshinori Koyama, Masatoshi Miyakoshi, Ryo Miyazaki, Hirokazu Yano, Masahiro Sota, Yoshiyuki Ohtsubo, Masataka Tsuda, Kentaro Miyazaki

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)


Several types of environmental bacteria that can aerobically degrade various aromatic compounds have been identified. The catabolic genes in these bacteria have generally been found to form operons, which promote efficient and complete degradation. However, little is known about the degradation pathways in bacteria that are difficult to culture in the laboratory. By functionally screening a metagenomic library created from activated sludge, we had earlier identified 91 fosmid clones carrying genes for extradiol dioxygenase (EDO), a key enzyme in the degradation of aromatic compounds. In this study, we analyzed 38 of these fosmids for the presence and organization of novel genes for aromatics degradation. Only two of the metagenomic clones contained complete degradation pathways similar to those found in known aromatic compound-utilizing bacteria. The rest of the clones contained only subsets of the pathway genes, with novel gene arrangements. A circular 36.7-kb DNA form was assembled from the sequences of clones carrying genes belonging to a novel EDO subfamily. This plasmid-like DNA form, designated pSKYE1, possessed genes for DNA replication and stable maintenance as well as a small set of genes for phenol degradation; the encoded enzymes, phenol hydroxylase and EDO, are capable of the detoxification of aromatic compounds. This gene set was found in 20 of the 38 analyzed clones, suggesting that this detoxification apparatus may be widespread in the environment.

Original languageEnglish
Pages (from-to)1335-1348
Number of pages14
JournalISME Journal
Issue number12
Publication statusPublished - 2009 Dec


  • Aromatic compounds
  • Degradation pathways
  • Extradiol dioxygenase
  • Metagenomics
  • Mobile genetic element

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics


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