Xxx. the Biochemistry of Dry-rot in Wood Iii. an Investigation of the Products of the Decay of Pine Wood Rotted by Merulius Lachrymans

THE previous observation [Barton-Wright & Boswell, 1929, 1931] that the dry-rot fungus Merulius lachrymans can be classified as of the "brown rot" type is confirmed. The present communication deals with the detailed constitution of the cellulose-containing, water-soluble and dilute alkali-soluble fractions which were only superficially studied in the earlier work. From the alcohol-soluble fraction a compound has been prepared which forms a 2:4-dinitrophenylhydrazone when treated according to Brady [1931]. This substance had a N-content similar to that of the dinitrophenylhydrazone of the pure substance previously isolated from the alcohol-soluble fraction of spruce wood. These three fractions appear to contain the products of the fungal activity. The benzenesoluble material seems to be unaffected both in amount and in constitution while evidence will be brought forward later that the increase in lignin content of rotted wood as compared with sound wood is solely due to the loss of cellulose degradation products as the gaseous residues of fungal respiration. The rotted wood used formed part of the panelling on the inside of the brick wall of an outhouse of an empty property. As will be seen from the figures of the bulk analysis the more rotted portion was in an advanced state of decay. The fungal mycelium had passed through the mortar between the bricks and produced, under the ivy covering the outside of the wall, fruit bodies identified as those of Merulius lachrymans. The wood of the panelling was a species of Pinus, probably P. resinosa, the Norway or Red Pine. The rotted wood was separated into two portions according to whether it could or could not be easily powdered by hand in a pestle and mortar. The more rotted portion powdered easily whilst the less rotted parts were reduced in a grinding mill. The methods of analysis and the preparation of the fractions in bulk were similar to those used previously with the following exceptions. The cellulose was isolated by the technique of Norman and Jenkins [1933] and the lignin by the use of 72% H2S04 instead of the chlorination method which had previously failed to provide a uniform product. The two samples of rotted wood gave the following analytical values (the analysis of a sound sample of P. resinosa is included for purposes of comparison): ~~~~~Table I