A new method using microtiter plates for screening mutants for the production of glucansucrases of Leuconostoc mesenteroides was developped. The method significantly increased the efficiency of the screening process for enzyme production of mutants. Several high-producing constitutive mutants for glucansucrase were selected from L. mesenteroides B-512FMC, B-742CB, B-1299CB, and B-1355C. Enzyme production of the mutants were stable for at least 6 months with culture transfer energy two weeks and as lyophilized cultures. The method has wide-ranging capabilities beyond the screening for glucansucrase-producing mutants and it could be used for the screening of many kinds of enzymes or compounds produced by microbial mutants.