BACKGROUNDAlcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) play important roles in alcohol metabolism. Therefore, a possible effective way to attenuate alcoholic liver damage is the exogenous supply of these two enzymes to the stomach as they might accelerate the oxidation of ethanol into nontoxic acetate. RESULTSADH and ALDH were coexpressed in Lactococcus lactis NZ3900 and used as treatments for acute alcoholic liver injury in mice. Intragastric ethanol administration was carried out at 5.6 g kg(-1) body weight per day in mice for 15 consecutive days and different doses of recombinant ADH-ALDH L. lactis treatment were administrated together with ethanol. A high dose of L. lactis recombinant ADH-ALDH treatment (ADH activity of 2000 U kg(-1) BW and ALDH activity of 1000 U kg(-1) BW) reduced the serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase levels by 38.1%, 54.8% and 23.2%, respectively, in ethanol-treated mice. Moreover, it also helped maintaining serum lipid levels and liver oxidative stress parameters against ethanol. Histopathological examination of mice livers revealed that L. lactis recombinant ADH-ALDH at a high dose (ADH activity of 2000 U kg(-1) BW and ALDH activity of 1000 U kg(-1) BW) protected liver tissue from the damage induced by ethanol. CONCLUSIONResults demonstrate that L. lactis with ADH and ALDH activity exhibit a dose-dependent protective effect on alcohol-induced liver damage in mice. (c) 2017 Society of Chemical Industry