Ammonium lactate production by Lactobacillus lactis BME5-18M in pH-controlled fed-batch fermentations

A process for efficient production of ammonium lactate by Lactobacillus lactis BME5-18M in pH-controlled fed-batch fermentation was developed. Effects of pH on the production of biomass and ammonium lactate in batch culture were studied at first. When the pH of the medium was maintained at 6.5, the highest biomass concentration and ammonium lactate production was obtained. The ammonium lactate production was remarkably improved by continuous feeding of glucose, when its residual concentration was between 5 and 10 g l(-1). Controlling the pH at 6.5 during the fed-batch fermentation under a constant feeding rate of 25 ml h(-1), the final concentration of 161.2 g ammonium lactate per liter was obtained, and the maximal cell dry weight and average ammonium lactate productivity obtained were 2.15 gDW l(-1) and 2.02 g l(-1) h(-1), respectively. (C) 2003 Elsevier B.V. All rights reserved.