The locus (sorbitol mannitol oxidation) is found on the chromosome of 's tripartite genome. Mutations at the locus reduce or abolish the ability of the bacterium to grow on several carbon sources, including sorbitol, mannitol, galactitol, d-arabitol and maltitol. The contribution of the locus to the metabolism of these compounds has not been previously investigated. Genetic complementation of mutant strains revealed that is responsible for growth on sorbitol and galactitol, while restores growth on mannitol and d-arabitol. Dehydrogenase assays demonstrate that SmoS and MtlK are NAD-dependent dehydrogenases catalysing the oxidation of their specific substrates. Transport experiments using a radiolabeled substrate indicate that sorbitol, mannitol and d-arabitol are primarily transported into the cell by the ABC transporter encoded by . Additionally, it was found that a mutation in either , which is found in an operon that encodes the fructose ABC transporter, or a mutation in , which encodes fructose kinase, leads to the induction of mannitol transport.