FTIR studies of the changes in wood chemistry following decay by brown-rot and white-rot fungi

A Fourier transform infrared (FTIR) spectroscopic study of changes in chemistry of Scots pine (Pinus sylvestris L.) sapwood and beech (Fagus sylvatica L.) decayed by Coniophora puteana ((Schumacher) Karsten), Coriolus versicolor ((L.) Quelet) and Phanerochaete chrysosporium (Burdsall) is presented. Wood was exposed to fungi for different durations up to 12 weeks, with decay assessed through weight loss and FTIR. The relative changes in intensities of spectral bands associated with lignin and carbohydrates as a result of decay were determined after different exposure periods. In wood decayed by C. puteana there was a progressive increase in lignin content relative to carbohydrate evident from increases in the relative height of lignin associated bands (at 1596, 1505, 1330, 1230 and 1122cm−1 in beech and 1596, 1511, 1268 and 1220cm−1in pine) and a corresponding decrease in the intensities of carbohydrate bands (at 1738, 1375, 1158 and 898cm−1). At higher weight losses, spectra for wood decayed by C. puteana have many similarities with that of Klason lignin isolated from wood. In contrast, wood decayed by P.chrysosporium showed selective type decay with a reduction in peak heights associated with lignin relative to carbohydrates. Although weight losses in samples exposed to C. versicolor were high (45.5% and 39.8% for beech and Scots pine, respectively, after 12 weeks) simultaneous decay resulted in little change in the relative intensities of the lignin and carbohydrate bands, with only a slight preference for lignin.