Screening of fungi capable of highly selective degradation of lignin in rice straw

Abstract

In order to screen for novel fungus with powerful delignification capability on rice straw, fungal samples found on woody surfaces were collected from several regions in China and were isolated and screened for their lignin-degrading properties on rice straw. After the individual isolates were cultivated on rice straw as the sole carbon substrate for 10 days, gravimetric fiber extraction analysis was used to determine the change in holocellulose and lignin content. Isolate 812 exhibited a high degree of lignin degradation at 34.7% while maintaining low holocellulose degradation at 2.1%, which performed better than the traditional white-rot fungus Phanerochaete chrysosporium with 28.3% lignin degradation and 28.4% holocellulose degradation. Isolate 812 was identified as Fusarium moniliforme based on its 18S rDNA gene sequence and its morphological characteristics. Ligninolytic enzyme assay indicated that the fungus produced lignin peroxidase and manganese peroxidase during solid-state and liquid fermentation. Above results indicated that we had screened a F. moniliforme isolate with highly efficient delignification capability and very slight damage to holocellulose. The newly isolated fungus could be used in biodegradation of lignocellulosic feedstock.