Summary Emissions of biogenic volatile organic compounds (bVOCs), are an important element in the global carbon cycle, accounting for a significant proportion of fixed carbon. They contribute directly and indirectly to global warming and climate change and have a major effect on atmospheric chemistry. Plants emit isoprene to the atmosphere in similar quantities to emissions of methane from all sources and each accounts for approximately one third of total VOCs. Although methanotrophs, capable of growth on methane, have been intensively studied, we know little of isoprene biodegradation. Here, we report the isolation of two isoprene‐degrading strains from the terrestrial environment and describe the design and testing of polymerase chain reaction (PCR) primers targeting isoA, the gene encoding the active‐site component of the conserved isoprene monooxygenase, which are capable of retrieving isoA sequences from isoprene‐enriched environmental samples. Stable isotope probing experiments, using biosynthesized 13C‐labelled isoprene, identified the active isoprene‐degrading bacteria in soil. This study identifies novel isoprene‐degrading strains using both culture‐dependent and, for the first time, culture‐independent methods and provides the tools and foundations for continued investigation of the biogeography and molecular ecology of isoprene‐degrading bacteria.

The mevalonate pathway is utilized for the biosynthesis of isoprenoids in many bacterial, eukaryotic, and archaeal organisms. Based on previous reports of its feedback inhibition, mevalonate kinase (MVK) may play an important regulatory role in the biosynthesis of mevalonate pathway-derived compounds. Here we report the purification, kinetic characterization, and inhibition analysis of the MVK from the archaeon Methanosarcina mazei. The inhibition of the M. mazei MVK by the following metabolites derived from the mevalonate pathway was explored: dimethylallyl diphosphate (DMAPP), geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), isopentenyl monophosphate (IP), and diphosphomevalonate. M. mazei MVK was not inhibited by DMAPP, GPP, FPP, diphosphomevalonate, or IP, a proposed intermediate in an alternative isoprenoid pathway present in archaea. Our findings suggest that the M. mazei MVK represents a distinct class of mevalonate kinases that can be differentiated from previously characterized MVKs based on its inhibition profile.