CLONING OF THE LACTOCOCCUS-LACTIS ADHE GENE, ENCODING A MULTIFUNCTIONAL ALCOHOL-DEHYDROGENASE, BY COMPLEMENTATION OF A FERMENTATIVE MUTANT OF ESCHERICHIA-COLI

The Lactococcus lactis adhE gene, which encodes a multifunctional alco hol dehydrogenase, has been cloned and characterized. A DNA fragment e ncoding the putative alcohol dehydrogenase domain of the AdhE protein was cloned by screening an L. lactis genomic library in a fermentative mutant of Escherichia coli and selecting for the ability to grow anae robically. Further analysis of the clone obtained allowed the cloning of the entire adhE gene sequence. Analysis of adhE expression in L. la ctis during anaerobiosis showed induction at the transcriptional level , especially in medium containing glucose. Constructed mutant strains produced reduced amounts of ethanol under anaerobic conditions. With t he L. lactis gene as a probe, adhE homologs were found in other indust rially relevant lactic acid bacteria.