The biotechnological potential of the extreme halophilic archaea Haloterrigena sp. H13 in xenobiotic metabolism using a comparative genomics approach

Abstract

Extreme halophilic archaea are thriving and dominant populations within hypersaline environments. Because of the extreme properties of the enzymes of halophilic archaea and similar metabolic abilities to their bacterial counterparts, our interests focus on their potential biotechnological applications. In this study, the partial genome of a newly isolated extreme halophilic archaeon, Haloterrigena sp. H13, was investigated. The genome size was estimated to be about 3.9 MB, and a genomic shotgun library was constructed. A total of 1479 clones from the library were sequenced once, and 1186 contigs were obtained. From these contigs, 580 open reading frames (ORFs) were identified, and 394 ORFs were annotated. From the partial genome of strain H13, we identified genes that may be involved in 1,2‐dichloroethane degradation, naphthalene/anthracene degradation, γ‐hexachlorocyclohexane degradation, 1‐/2‐methylnaphthalene degradation and benzoate degradation via CoA ligation. Among the identified ORFs, gene homologs of (S)‐2‐haloacid dehalogenase (EC 3.8.1.2) and salicylate hydroxylase (EC 1.14.13.1), which might be involved in the degradation of dichloroethane, γ‐hexachlorocyclohexane and naphthalene, were found in the partial genome sequence of strain H13. According to the current genome annotation of peripheral metabolic pathways and the putative xenobiotic‐degrading enzymes, the potential of extreme haloarchaea in bioremediation applications is proposed.

Keywords:

• comparative genomics
• extremophiles
• halophilic archaea
• xenobiotic degradation

Acknowledgements

The initial sampling and enrichment of Haloterrigena sp. H13 were supported by R.A. Mah and R.P. Gunsalus from UCLA (University of California, Los Angeles). We are grateful to Professor Y.‐L. Lai, (National Taiwan University), for critically editing a draft of the manuscript.