IDENTIFICATION AND RETTING EFFICIENCIES OF FUNGI ISOLATED FROM DEW-RETTED FLAX IN THE UNITED-STATES AND EUROPE

Seven strains of filamentous fungi and one yeast were isolated from fl ax that was dew retted in the United States. These filamentous fungi w ere subcultured to purity and identified, and six appear not to have b een reported earlier as isolates from dew-retted flax, Five of the pur ified U.S. strains, two fungi isolated from flax that was dew retted i n Europe, and a laboratory culture of Aspergillus sojae were tested fo r their ability to ret flax stems, The monocultures were evaluated for the degree of retting, fiber strength, dry weight loss, and tactile r esponse (i.e., feel of softness) as reflected in the retted fiber, Str uctural modifications of representative samples of the retted Bar were assessed by scanning electron microscopy. All of the filamentous fung i were able to carry out some retting, whereas the isolated yeast coul d not. All organisms produced pectinases when they were cultivated in shake flasks on ball-milled flax as the sole carbon source, Some fungi also produced cellulases, mannanases, and xylanases, Rhizomucor pusil lus and Fusarium lateritium were noteworthy as retting organisms by th eir high level of pectinase activity, ability to attack noncellulosic cell types without attacking cellulose, capacity to penetrate the cuti cular surface of the stem, and efficient fiber release from the core, The results indicated that these organisms deserve further study as po tential organisms for retting of bast fibers in industrial application s.