Retting flax with endopolygalacturonase from Rhizopus oryzae

Retting, which is the process of separating fibers from nonfiber tissues in bast plants, is the major problem in processing flax for linen, and new methods, especially enzyme retting, are being pursued to overcome this problem. Production of an endopolygalacturonase (EPG) from Rhizopus oryzae, which was isolated earlier from dew retted flax, is optimized, and the enzyme is subsequently purified and characterized. Purified EPG is evaluated for its efficiency in retting flax alone and in combination with other cell wall degrading enzymes. The Fried test, light and scanning electron microscopy, and fiber strength and fineness properties indicate that EPG alone (without additional enzymes) plus chelator gives retting efficiencies similar to previously used enzyme mixtures. The addition to EPG of pectin methyl esterase, pectin lyase, xylanase, or endoglucanase does not improve retting efficiency or strength and fineness properties of the retted flax fibers over EPG alone. Spray enzyme retting of a 50 g flax sample with EPG/chelator formulation produces retted flax fibers with strength and fineness properties similar to those retted with a commercial enzyme mixture. Our results indicate that EPG is of paramount importance in flax retting, and they suggest an opportunity, through cloning technology, to produce a consistently effective but simplified enzyme formulation for flax retting.