Biological degradation of tannins in sericea lespedeza (Lespedeza cuneata) by the white rot fungi Ceriporiopsis subvermispora and Cyathus stercoreus analyzed by solid-state 13C nuclear magnetic resonance spectroscopy

Abstract

Leaves of sericea lespedeza exhibit a high proportion of condensed tannin, resulting in poor forage quality. The white rot fungi Ceriporiopsis subvermispora and Cyathus stercoreus are known to preferentially degrade lignin in a variety of plants and were evaluated for their ability to degrade condensed tannin from sericea leaves with the aim of improving digestibility. Relative levels of condensed tannin, cutin, pectin, and cellulose were monitored as a function of fungal treatment by solid-state cross- polarization and magic angle spinning 13C nuclear magnetic resonance spectroscopy. Total soluble phenolics, soluble tannins, and soluble and insoluble proanthncyanidin levels in fungus-treated and control samples were measured by established chemical techniques. Results indicate that both species of fungus preferentially degrade condensed tannin and that C. subvermispora is markedly superior to C. stercoreus in this capacity.