Catalyzes the NADH-dependent reduction of methylglyoxal (2-oxopropanal) in vitro (PubMed:16813561). It is not known if this activity has physiological significance (PubMed:16813561). Cannot use NADPH as a cosubstrate (PubMed:16813561). Seems to play some role in intestinal colonization (PubMed:20562286). hydroxyacetone + NAD(+) = H(+) + methylglyoxal + NADH kcat is 15.7 sec(-1) with methylglyoxal as substrate. kcat is 2 sec(-1) with DL-glyceraldehyde as substrate. Monomer. Is 3.5-fold up-regulated in vivo in intestinal environment compared to the level for in vitro cultures. Deletion of this gene affects intestinal colonization by E.coli, since a deletion mutant reaches a 1.2-log-lower cecal concentration than the wild-type. Can be used in an engineered metabolic pathway for 1,2-propanediol and 1-propanol production. 1-propanol is a potential fuel substitute to petroleum. Belongs to the aldo/keto reductase family. Aldo/keto reductase 11 subfamily.