Re-analysis of omics data indicates Smithella may degrade alkanes by addition to fumarate under methanogenic conditions

Here we comment on three aspects of a recent report in ISME J ( Embree et al., 2013 ), which concluded that: the draft genome of Smithella ME-1 lacks genes encoding alkylsuccinate synthase (ASS) subunits; it therefore does not express those genes when grown on n- hexadecane in mixed culture under methanogenic conditions; and it may use an alternate mechanism to initiate anaerobic n -hexadecane degradation. We have re-analyzed the draft genome of Smithella ME-1 and three metatranscriptomes, and reached conclusions opposite to those of Embree et al. (2013) .