title: New approach for selective separation of dilute products from simulated clostridial fermentation broths using cyclodextrins.
abstract: The ability of cyclodextrins (CD) to form crystalline insoluble complexes with organics was explored in this study in view of a selective separation of dilute products obtainable from three clostridial fermentation systems. To this purpose, a product or a product mixture at a concentration of 0.150 mM each were treated with alpha-CD or beta-CD (0.150 mM) in aqueous solutions as well as in a nutrient broth as a simulated fermentation medium. In the acetone-butanol-ethanol system, and in the butanol-iso-propanol system, alpha-CD was found to precipitate selectively 48% and 46% butanol after 1 h agitation at 30 degrees C. However, beta-CD was found to be superior for the butyric acid-acetic acid system because it selectively precipitated 100% butyric acid under the same conditions. Cooling the three product system with alpha-CD to 4 degrees C for 24 h increased significantly the crop of precipitates but decreased the selectivity for either butanol or butyric acid. Cyclodextrins were thus shown to offer potentially a new exciting possibility for downstream processing of low-concentration fermentation products.
authors.affiliation: Department of Applied Microbiology, The Hebrew University, Jerusalem, Israel 91010.
authors.forename: H
authors.initials: H
authors.lastname: Shity
authors.forename: R
authors.initials: R
authors.lastname: Bar