microorganisms Article Sphingopyxis sp. Strain OPL5, an Isoprene-Degrading Bacterium from the Sphingomonadaceae Family Isolated from Oil Palm Leaves Nasmille L. Larke-Mejía 1 , Ornella Carrión 1 , Andrew T. Crombie 2, Terry J. McGenity 3 and J. Colin Murrell 1,* 1 School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK;
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[email protected]; Tel.: +44-01603-592959 Received: 2 September 2020; Accepted: 7 October 2020; Published: 10 October 2020 Abstract: The volatile secondary metabolite, isoprene, is released by trees to the atmosphere in enormous quantities, where it has important effects on air quality and climate. Oil palm trees, one of the highest isoprene emitters, are increasingly dominating agroforestry over large areas of Asia, with associated uncertainties over their effects on climate. Microbes capable of using isoprene as a source of carbon for growth have been identified in soils and in the tree phyllosphere, and most are members of the Actinobacteria. Here, we used DNA stable isotope probing to identify the isoprene-degrading bacteria associated with oil palm leaves and inhabiting the surrounding soil. Among the most abundant isoprene degraders of the leaf-associated community were members of the Sphingomonadales, although no representatives of this order were previously known to degrade isoprene. Informed by these data, we obtained representatives of the most abundant isoprene degraders in enrichments, including Sphingopyxis strain OPL5 (Sphingomonadales), able to grow on isoprene as the sole source of carbon and energy.