Location: Bioenergy ResearchTitle: Effects of pH and Corn Steep Liquor Variability on Mannitol Production by Lactobacillus intermedius NRRL B-3693 Author
Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2010
Publication Date: 5/1/2010
Citation: Saha, B.C., Racine, F.M. 2010. Effects of pH and Corn Steep Liquor Variability on Mannitol Production by Lactobacillus intermedius NRRL B-3693. Applied Microbiology and Biotechnology. 87(2):553-560. 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. A lactic acid bacterium from the Agricultural Research Service 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 paper, the effects of pH and corn steep liquor variability on the production of mannitol are reported. The results are very promising for developing a low cost fermentation process technology for production of mannitol commercially.
Technical Abstract: Lactobacillus intermedius NRRL B-3693 produce mannitol, lactic acid, and acetic acid when grown on fructose at 37 deg C. The optimal pH for mannitol production from fructose by the heterofermentative lactic acid bacterium (LAB) in pH controlled fermentation was at pH 5.0. It produced 160.7±1.1 g mannitol in 40 h with a volumetric productivity of 4.0 g/l-h in a simplified medium containing 250 g fructose, 50 g corn steep liquor (CSL), and 33 mg MnSO4 per l. However, the mannitol production by LAB was severely affected by the variability of CSL. The supplementation of CSL with each of soy peptone (5 g/l), tryptophan (50 mg/l), and commercial protease preparation (2 ml/100 g of CSL) enhanced the performance of the inferior CSL and thus helped to overcome the nutrient limitations.