Structure alteration of lignin in corn stover degraded by white-rot fungus Irpex lacteus CD2

Lignin was isolated from corn stover degraded by Irpex lacteus CD2 to better understand how white-rot fungi decomposed corn stover lignin, and the structure alterations were analyzed by elemental analysis, FTIR, 13C NMR, 1H NMR, and UV spectra. These investigations illustrate significant structure differences between degraded and undegraded corn stover lignin that, in I. lacteus CD2 degraded lignin, aliphatic hydroxyl groups decreased remarkably, while conjugated carbonyl groups increased obviously. Moreover, the content of etherified guaiacyl units enhanced nearly twice, with the content of etherified syringyl units declining simultaneously. The increasing content of CH3 in ArOCH3 and the decreasing contents of guaiacyl and syringyl units were also observed in the degraded lignin, supposed to be the result of aromatic ring cleavage. By isolating lignin from degraded corn stover, the research demonstrates lignin structure differences contributed by white-rot fungus I. lacteus CD2 more profound and clear than investigations carried out by researching on lignin model compounds.