Catabolism of diethyl ether as a sole carbon and energy source by Mycolicibacterium sp. ELW1

The model isobutylene (IB)-metabolizing strain Mycolicibacterium sp. ELW1 grew aerobically on diethyl ether (DEE) as a sole carbon and energy source. DEE supported an equivalent biomass yield to IB despite strong effects of DEE concentration on growth rate and lag phase. Differential expression analysis of the transcriptome revealed extensive transcriptional remodeling during growth on DEE compared to fructose, including the substantial upregulation of chromosomally-encoded alcohol and acetaldehyde dehydrogenases, and the plasmid‑encoded isobutylene monooxygenase (IMO). In resting‑cell assays, IB‑grown cells oxidized DEE twice as rapidly as DEE‑grown cells and ethanol and acetaldehyde temporarily accumulated during DEE oxidation. In contrast, no products were detected during DEE oxidation by DEE-grown cells. Loss of the megaplasmid pELW1‑1 prevented growth on both IB and DEE while activity‑based labeling (ABL) analyses suggest the plasmid-encoded IMO is the major diyne‑reactive monooxygenase in both IB and DEE-grown cells. Supplementing cultures growing on DEE with small amounts of IB increased both DEE consumption rates and biomass yields, and this effect appears to involve decreases in the lag phase associated with growth on DEE alone. In contrast to some previous studies of DEE catabolism which have concluded DEE is unable to induce expression of soluble di-iron monooxygenases (SDIMOs), collectively, our results indicate DEE catabolism leads to substantial expression of the plasmid‑encoded IMO and is supported by expression of chromosomally encoded alcohol and aldehyde dehydrogenases.