Eight heterofermentative lactic acid bacteria were compared as to their ability to convert D-fructose to D-mannitol. Four promising strains were identified and the effects of growth temperature, pH, and nitrogen flushing on mannitol production by these strains were studied in batch bioreactor cultivations. In contrast to earlier findings, a high growth temperature was observed to improve the yield of mannitol from fructose with Lactobacillus fermentum. When Lb, fermentum was grown at 25, 30, and 35degreesC, yields of 86.4 +/- 0.8, 88.9 +/- 2.4, and 93.6 +/- 0.6 mol%, respectively, were achieved. In general, constant nitrogen gas flushing of the growth media was found to improve the mannitol yields, but not the volumetric mannitol productivities. Applying the most promising strain in a batch mannitol production experiment, high average and maximum volumetric mannitol productivities (7.6 and 16.0 g/l/h, respectively) were achieved, (C) 2002 Elsevier Science Ltd. All rights reserved.