Identification and characterisation of isoprene‐degrading bacteria in an estuarine environment

Abstract

SummaryApproximately one-third of volatile organic compounds (VOCs) emitted to the atmosphere consists of isoprene, originating from the terrestrial and marine biosphere, with a profound effect on atmospheric chemistry. However, isoprene provides an abundant and largely unexplored source of carbon and energy for microbes. The potential for isoprene degradation in marine and estuarine samples from the Colne Estuary, UK, was investigated using DNA-Stable Isotope Probing (DNA-SIP). Analysis at two timepoints showed the development of communities dominated by Actinobacteria including members of the genera Mycobacterium, Rhodococcus, Microbacterium and Gordonia. Representative isolates, capable of growth on isoprene as sole carbon and energy source, were obtained from marine and estuarine locations, and isoprenedegrading strains of Gordonia and Mycobacterium were characterised physiologically and their genomes were sequenced. Genes predicted to be required for isoprene metabolism, including four-component isoprene monooxygenases (IsoMO), were identified and compared with previously characterised examples. Transcriptional and activity assays of strains growing on isoprene or alternative carbon sources showed that growth on isoprene is an inducible trait requiring a specific IsoMO. This study is the first to identify active isoprene degraders in estuarine and marine environments using DNA-SIP and to characterise marine isoprene-degrading bacteria at the physiological and molecular level.

On the Enigma of Glutathione-Dependent Styrene Degradation in Gordonia rubripertincta CWB2

“…Homologous clusters can be found in several actinobacteria (28)(29)(30), e.g., in R. opacus 1CP and Gordonia sp. i37 (21). The other putative PAR is not part of a cluster.…”

“…Further, Gordonia sp. strain i37 has a homologous gene cluster in the neighborhood of a recently recorded isoprene degradation cluster (contig257, WP_079929940 to WP_079929944; contig258, OPX14963 and OPX14964 [56 and 4%, respectively]) (21).…”

“…Homologous proteins from cluster S3 were recently found in Gordonia sp. i37 next to a homologous to cluster S2 (21). The 13,983-bp insertion of Nocardioides sp.…”

“…Interestingly, Gordonia sp. i37 harbors a similar cluster in the proximity of an isoprene degradation cluster (21). However, there are no characterized homologs available in the database, and thus the specific function of these proteins remains unclear.…”

“…AD45 (AJ249207) and also in Gordonia sp. i37 (21,54). Actinobacteria from the genera Mycobacterium, Rhodococcus, and Gordonia were constantly detected in different environments as isoprene degraders (21,54,55).…”