Submitted to: Enzyme and Microbial Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2006
Publication Date: June 1, 2006
Citation: Saha, B.C. 2006. Production of mannitol from inulin by simultaneous enzymatic saccharification and fermentation with Lactobacillus intermedius NRRL B-3693. Enzyme and Microbial Technology. 39:991-995. Interpretive Summary: Mannitol, a naturally occurring 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 an 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. Inulin, a polymer of fructose, is abundantly found in certain roots and tubers of plants such as Jerusalem artichoke, chicory, and dahlia. This research shows that inulin can serve as a renewable feedstock for production of mannitol. This will help to expand the use of inulin for production of value-added chemicals.
Technical Abstract: The production of mannitol by Lactobacillus intermedius NRRL B-3693, using inulin as a substrate, was evaluated at pH 5.0 and 37 deg C. The bacterium produced mannitol (106.2 ± 0.3 g/l) from dilute acid hydrolyzate (pH 2.0, 121 deg C, 15 min) of inulin (150 g/L) in 34 h. It also produced mannitol from inulin by simultaneous saccharification and fermentation (SSF) at pH 5.0 and 37 deg C using inulinase (8 U/g substrate). From 300 g/L inulin, the L. intermedius B-3693 produced 207.4 ± 1.2 g mannitol in 72 h by SSF. The fermentation time decreased from 72 h to 62 h using a mixture of fructose and inulin (1:1, total, 300 g/L). When fructose and inulin mixture (3:5, total 400 g l-1 ) was used as substrate, the bacterium produced 227.9 ± 1.8 g mannitol l-1 with a yield of 0.57 g g-1 substrate after 110 h of SSF. This is the highest level of mannitol ever produced by a microorganism reported in literature.