Blue Haze and Bacteria

February 14, 2019 10:22: am | by Sarah Clarke

Have you ever wondered what causes the blue haze over the Blue Ridge Mountains of Virginia in the USA or the Blue Mountains in Australia? It is caused by a volatile organic compound called isoprene that is released in huge amounts by trees. Isoprene is an interesting trace gas in the atmosphere as it can cause both global warming and cooling. Unlike methane, which is consumed by methane oxidising bacteria, we know little about the biogeochemical cycles for isoprene and if microbes can consume this climate-active gas. Andrew Crombie and colleagues at UEA hypothesised that the leaves of high isoprene-emitting trees such as poplar. Using stable isotope probing, metagenomics and metatranscriptomics they showed that the phyllosphere of poplar did indeed harbour isoprene-degrading bacteria of the genus Rhodococcus which had been previously been found in soil environments and also more diverse isoprene degraders such as Variovorax, providing a new model isoprene-degrader to study the metabolism of isoprene in the lab. The work, recently published in PNAS nicely demonstrates the variety of isoprene degraders present in the phyllosphere of poplar trees. https://doi.org/10.1073/pnas.1812668115