Fungal Pretreatment of Pinus Radiada using New Zealand Native Strains of Stereum Hirsutum and Trametes Versicolor

Abstract

Lignocellulosic material, the most abundant renewable bioresource in the world, is the most promising material to produce biofuel. Radiata pine is a versatile, fast-growing, medium-density softwood, suitable for a wide range of end-uses. 89% of the New Zealand plantation forests are of this species. Consequently, qualities such as being abundant in New Zealand, being cheap and fast-growing, and containing plenty of cellulose make this lignocellulosic material a favourable feedstock for biofuel production. The main issue in using lignocellulosic materials such as radiata pine for production of biofuel is the low accessibility of cellulose to enzymes and microorganisms, due to the rigid association of cellulose with the 3-dimensionally complex lignin biopolymer. Therefore, pretreatment of lignocelluloses is a critical step in biofuel production from such materials. Of the pretreatments, fungal treatment has become an important process due to its low energy demands and selective degradation of lignin and hemicellulose. In this study the effect of two white rot fungi, (New Zealand native strains) Stereum Hirsutum and Trametes Versicolor, on the digestibility and crystallinity of pine was investigated. Pretreatment for each type of fungi was carried out over periods of 3 to 7 weeks. Pretreatment efficiencies were compared by evaluating lignin degradation and crystallinity over the pretreatment periods. The results showed that the strains used in this study are able to selectively degrade radiata pine wood. It was found that longer pretreatment increases lignin degradation. Crystallinity of woody material significantly increased over 3 and 5 weeks of pretreatment followed by a significant decrease at week 7. The information provided in this study may help in further developing this energy-saving and environmentally friendly pretreatment method for bioenergy production in New Zealand.