Enzymatic degumming of ramie bast fibers

East fibers from ramie (Boehmeria nivea) were treated with cell-free cultur e supernatants from an Amycolata sp. and a recombinant Streptomyces lividan s strain expressing the Amycolata pectate lyase to investigate the degummin g effects of different extracellular polysaccharide-degrading enzymes. Cult ure supernatants from the Amycolata sp. with high pectate lyase activities were most effective in fiber separation and reduced the gum content of rami e fibers by 30% within 15 h. Xylanase activity produced by the Amycolata sp . contributed little to the degumming. Electron micrographs showed that the crude pectate lyase from the Amycolata sp. removed plant gum more efficien tly from decorticated ramie bast fibers than the purified enzyme. Similarly , degumming with the crude enzyme of the Amycolata sp, and the recombinant S. lividans strain for 24 h resulted in fibers with a residual gum content of 14.7 and 17.3%, respectively. Degumming with the crude enzyme of the rec ombinant Streptomyces strain was slightly improved by the addition of a com mercial pectinesterase. No significant degumming was observed with the crud e enzyme from an S. lividans strain that did not produce the Amycolata pect ate lyase. These results indicate that the pectinolytic activity of the Amy colata sp. plays an active role in degumming of ramie bast fibers. (C) 2000 Elsevier Science B.V. All rights reserved.