Based on the NMR spectroscopy data and genome analysis, we propose that under anaerobic conditions, EG is first dehydrated to acetaldehyde by ethanolamine ammonia lyase (EAL) and then disproportionated by alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) to ethanol and acetyl-CoA, respectively. The latter is further converted into acetate by phosphate acetyl transferase (PTA) and acetate kinase (ACK) coupled to ATP formation by substrate-level phosphorylation (Figure ). Both, acetate, and ethanol are transported outside of the cell. Ethanol can reenter the cell and be converted further into acetate (Figure ). A similar anaerobic EG metabolism was observed in the acetogen Acetobacterium woodii . Genome analysis of I. sakaiensis validates our proposed EG metabolism under anaerobic conditions (Figure ) as all mentioned enzymes (EAL, ADH, ALDH, PTA, and ACK) are present in the bacterial genome (Table ) , except diol dehydratase (pdu gene) that is commonly employed for dehydration of EG to acetaldehyde . However, its homolog EAL (eut gene) is available and previous studies have demonstrated that the eut bacterial microcompartment shares similar features with that of pdu microcompartment in terms of encoded enzymes and chemical reactions . Further, it has been shown that Salmonella enterica can dehydrate diol to acetaldehyde when a pdu enzyme was replaced by the eut homolog . Previous observations therefore confirm that eut gene in I. sakaiensis can dehydrate EG to acetaldehyde.