Release of Aromatic Compounds from Birch and Spruce Sawdusts during Decomposition by White-rot Fungi

Abstract

DURING investigations into the decomposition of lignin by soil micro-fungi, it was found that a large number of these were able to decompose several aromatic compounds which are believed to be related to lignin¹. In an attempt to discover whether such compounds are released on biological decomposition of lignin, two wood-rotting fungi, Polystictus versicolor and Trametes pini, both white-rots, were grown on birch and spruce sawdusts. 25 gm. of sawdust (previously extracted with alcohol-benzene) was added to each flask and moistened with 40 ml. of a mineral salts medium (0.1 gm. potassium dihydrogen phosphate, 0.05 gm. potassium chloride, 0.05 gm. magnesium sulphate, 0.5 gm. peptone, 1 gm. glucose, 100 ml. water). The flasks were sterilized by steaming for one hour on three successive days. The fungi produced much growth which penetrated the sawdust, causing it to become lighter in colour. After six months incubation at 22° C, 9 gm. of this material was extracted with 2 per cent sodium hydroxide. On acidification of the extract a considerable precipitate was formed which was centrifuged off; the supernatant was then extracted with ether. The ether was evaporated off and the residue dissolved in a small volume of absolute alcohol for application to chromatography papers. These were developed with a single-phase mixture consisting of n-propanol – ammonia (sp. gr. 0.880) – water (80 : 5 : 15), run for two periods of 24 hr. at 21° C. and dried between successive runs. Two sprays were used: (a) diazotized sulphanilic acid² for phenolic groups, and (b) 2 : 4-dinitrophenylhydrazine³ for aldehydes.