The ascomycete Xylaria polymorpha produces an acetyl esterase that solubilises beech wood material to release water-soluble lignin fragments

Abstract

Three ascomycetous soft-rot fungi belonging to the family Xylariaceae were found to produce high levels of a p-nitrophenyl acetate-hydrolyzing activity during growth on lignocellulosic materials, i.e., wheat straw and beech wood chips. Accordingly, Kretzschmaria deusta, Morchella elata, Xylaria polymorpha were seemingly most noteworthy acetyl esterase producers and, of which, X. polymorpha (strain A35) was chosen for further studies. Induction study indicated that raw carbohydrate sources, such as beech wood, rape straw, birch wood, and wheat straw, were extremely important for acetyl esterase production. Acetyl esterase of X. polymorpha was produced in solid-state culture on wheat straw and purified by different steps of anion-exchange and size-exclusion chromatography. This purified enzyme (MW = 44 kDa and pI values of 3.5–3.6) exhibited the capability to solubilise in vitro beech wood to release water-soluble lignin fragments with molecular masses of 1–3 kDa as analyzed by high performance size exclusion chromatography.