Isolation and characterization of tetrahydrofuran-degrading Rhodococcus aetherivorans strain M8

We isolated tetrahydrofuran (THF)-degrading bacteria from waste sludge obtained from a chemical factory in Japan. The isolate designated as strain M8 was identified as Rhodococcus aetherivorans by sequence analysis of its 16S rRNA gene. It grew in a medium containing THF as the sole source of carbon and energy, and its optimal growth pH range and temperature were 6–9 and 37 °C, respectively. Strain M8 grew even in the presence of 35 mM THF. For its growth, this bacterium used 1,4-butanediol and γ-butyrolactone, which are supposed to be metabolites of THF. To elucidate the pathway involved in THF metabolism in strain M8, the resting cell reaction was performed, and the metabolites of THF were analyzed. In the resting cell reaction, 5 mM THF was completely degraded within 5 h. Cells were harvested at 2, 3, and 4 h after the initiation of the reaction; the intermediates accumulated in the cells were extracted using methanol and were derivatized using phenyl boronate. Gas chromatography–mass spectrometry (GC–MS) analysis of the derivatized products showed 4-hydroxybutyrate accumulating in the resting cells. This result suggests that R. aetherivorans strain M8 degrades THF via the oxidation pathway.