Joseph C. Mcauliffe

Isolation of isoprene degrading bacteria from soils, development of isoA gene probes and identification of the active isoprene degrading soil community using DNA‐stable isotope probing

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 (13) C-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.

Industrial Enzymes and Biocatalysis

All life processes, whether plant, animal, or microbial, depend upon a complex network of enzyme-catalyzed chemical reactions for cellular growth and maintenance [1–3]. As protein-based catalysts, enzymes facilitate reactions by enabling alternate reaction mechanisms with lower overall activation energy, without modifying the thermodynamic equilibrium constant or the free energy change of a chemical transformation. They generate enormous kinetic rate accelerations, often exceeding factors of 1012-fold relative to the rate of the uncatalyzed reaction. Enzymes are capable of performing many different chemistries, can be produced on a large scale, and typically operate at ambient temperatures and near neutral pH [4, 5]. These properties have captured the attention of generations of scientists and engineers over the past century and enabled the practical use of enzymes as industrial catalysts. Enzymes are now used extensively across a wide range of applications as demand for environmentally sustainable processes increases in a number of industries [6–9].