Control of Malolactic Fermentation in Wine. 2. Isolation and Characterization of a New Malolactic Organism

¹ Biologicals, 20 Victoria Street, Toronto, Canada M5C 2NB
² Department of Microbiology and Immunology, University of California, Berkeley, California 94720.

Several natural isolates of lactic acid bacteria were made from wines which were undergoing spontaneous malolactic fermentation. These organisms were screened for: rapid growth; rapid metabolism of malic acid; and optimal growth response to pH, alcohol, SO₂, fumaric acid, and temperature. Of the natural isolates studied, a strain designated B44·40 showed the greatest potential for rapid growth, efficient metabolism of malate, and greatest tolerences to variations of pH and temperature. When B44·40 was compared to ML-34 and PSU-1, it was found to grow more rapidly in synthetic media and to metabolize organic substrates present in wine such as malate and glucose at a more rapid rate than either ML-34 or PSU-1. B44·40, ML-34 and PSU-1 showed similar tolerances to alcohol and fumaric acid. B44·40 showed less tolerance to SO₂ than either ML-34 or PSU-1.