Lignin is randomly constructed polymer of phenylpropanoids, which contribute to recalcitrance of lignin. With biorefinery concept, lignin is considered as remarkably aromatic biopolymer, and studies on its modification have recently been conducted.
White rot fungi (WRF) secreting ligninolytic enzymes are promising for enzymatic modification. Although biodegradation of lignin by WRF has been studied for decades, modification of industrial lignin by enzymatic means is still an extremely challenging task. Therefore, detailed investigations are more necessary.
The aims of this study were to examine biomodification mechanism of synthetic lignin by WRF, and to evaluate effect of ligninolytic enzymes. Synthetic lignin used in this study was synthesized from coniferyl and sinapyl alcohol. This polymer, dehydrogenative polymer (DHP) was used as substrate to elucidate the mechanism of microbial and enzymatic modification of lignin.
At first, phenolic hydroxyl group of DHP was analyzed by aminolysis reaction. Phenolic hydroxyl group of DHP treated by A. biennis increased than control, indicating that A. biennis have an effect on cleavage of ether bonds. Additionally, the molecular weight and changes of ether bonds in DHP will be analyzed by gel permeation chromatography and derivatization followed by reductive cleavage method, respectively. Degradation products of DHP by A. biennis will be analyzed by chromatography. Activities of ligninolytic enzymes tended to decrease with addition of DHP.
Consequently, this study is expected to help to understand the biomodification mechanism of synthetic lignin by A. biennis and to evaluate availability of A. biennis in biomodification of lignin for value added application of lignin.