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Poplar phyllosphere harbors disparate isoprene-degrading bacteria

Crombie, Andrew T and Larke-Mejia, Nasmille L and Emery, Helen and Dawson, Robin and Pratscher, Jennifer and Murphy, Gordon P and McGenity, Terry J and Murrell, J Colin (2018) 'Poplar phyllosphere harbors disparate isoprene-degrading bacteria.' Proceedings of the National Academy of Sciences. ISSN 0027-8424

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Abstract

The climate-active gas isoprene (2-methyl-1,3-butadiene) is released to the atmosphere in huge quantities, almost equaling that of methane, yet we know little about the biological cycling of isoprene in the environment. Although bacteria capable of growth on isoprene as the sole source of carbon and energy have previously been isolated from soils and sediments, no microbiological studies have targeted the major source of isoprene and examined the phyllosphere of isoprene-emitting trees for the presence of degraders of this abundant carbon source. Here, we identified isoprene-degrading bacteria in poplar tree-derived microcosms by DNA stable isotope probing. The genomes of isoprene-degrading taxa were reconstructed, putative isoprene metabolic genes were identified, and isoprene-related gene transcription was analyzed by shotgun metagenomics and metatranscriptomics. Gram-positive bacteria of the genus Rhodococcus proved to be the dominant isoprene degraders, as previously found in soil. However, a wider diversity of isoprene utilizers was also revealed, notably Variovorax, a genus not previously associated with this trait. This finding was confirmed by expression of the isoprene monooxygenase from Variovorax in a heterologous host. A Variovorax strain that could grow on isoprene as the sole carbon and energy source was isolated. Analysis of its genome confirmed that it contained isoprene metabolic genes with an identical layout and high similarity to those identified by DNA-stable isotope probing and metagenomics. This study provides evidence of a wide diversity of isoprene-degrading bacteria in the isoprene-emitting tree phyllosphere and greatly enhances our understanding of the biodegradation of this important metabolite and climate-active gas.

Item Type: Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 13 Dec 2018 10:54
Last Modified: 14 Aug 2019 10:16
URI: http://repository.essex.ac.uk/id/eprint/23631

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