Influence of nutrient amendment on the biodegradation of wheat straw during solid state fermentation with Trametes versicolor

The present study proposes a system whereby lignin biodegradation in lignocellulosic units may be optimised with the minimum loss of cellulose and other organic matter. Lignin, cellulose and organic matter losses were followed at 7-day intervals during 35-day solid state fermentation of wheat straw with Trametes versicolor with and without amendment carbon (C) and nitrogen (N) sources. Substrate supplementation with a C source favoured degradation of lignin; glucose as the C source was better than beet pulp molasses. Ammonium N slowed lignin removal. Lignin loss during 35-day fermentation in the presence of glucose was 42% as compared with 17.1% in the unamended wheat straw. The highest ratios of lignin loss to cellulose loss (9.55:1) and to organic matter loss (3.34:1) occurred in the first 14 days of fermentation when the straw was amended with glucose. These observations indicate that for efficient ligninolysis, it is appropriate to terminate fermentation of the glucose-amended straw at the 14-day stage at which 36.3% lignin degradation occurred at the cost of only 3.8% cellulose and 10.7% organic matter.