Submitted to: Process Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2007
Publication Date: 11/1/2007
Citation: Racine, F.M., Saha, B.C. 2007. Production of mannitol by Lactobacillus intermedius NRRL B-3693 in fed-batch and continuous cell-recycle fermentations. Process Biochemistry. 42:1609-1613. Interpretive Summary: Mannitol, a naturally occurring sugar alcohol, is widely used in the food, pharmaceutical, medicine, and chemical industries. It is currently produced as a 25/75 mixture of mannitol and sorbitol (another sugar alcohol) by high pressure hydrogenation of 50/50 fructose/glucose mixture (corn derived sugars) in aqueous solution at high temperature with a catalyst. The chemical process is inefficient. One lactic acid bacterium from the ARS Culture Collection (Peoria, IL) was found to be an excellent producer of mannitol from fructose using corn steep liquor (by-product of corn wet-milling industries) as an inexpensive industrial nutrient source. In this research, improved fermentation processes using fed-batch and continuous cell recycle systems have been developed for mannitol production by this bacterium. This is the first report of achieving very high productivity of mannitol by any lactic acid bacterium.
Technical Abstract: Improved fermentation processes were developed for the production of mannitol by a heterofermentative lactic acid bacterium (Lactobacillus intermedius NRRL B-3693). A fed-batch fermentation protocol overcame limitations caused by high substrate concentrations. The process was developed using primarily corn steep liquor as an inexpensive industrial nutrient source. The fed-batch process resulted in the accumulation of 176 g mannitol from 184 g fructose and 92 g glucose per L of final fermentation broth in 30 h with a volumetric productivity of 5.9 g/L.h. Further increases in volumetric productivity of mannitol were obtained in a continuous cell-recycle fermentation process that reached more than 40 g/L.h. This is the first report of such a high volumetric productivity of mannitol by a heterofermentative lactic acid bacterium.