Potential of the new endophytic fungusHormonemasp. CECT-13092 for improving processes in lignocellulosic biorefineries: biofuel production and cellulosic pulp manufacture

Abstract

BACKGROUND The utility of the ascomycete Hormonema sp. CECT-13092, an endophytic fungal strain recently isolated and identified from a eucalyptus tree in Spain, was investigated in different biorefineries-industrial processes. The strain was used to improve the enzymatic saccharification and pulping of Eucalyptus globulus wood; and liquid culture of the strain enriched in laccase activity was used for E. globulus Kraft pulp biobleaching in presence of acetosyringone as mediator. RESULTS With regard to enzymatic saccharification, treatment with Hormonema sp. and autohydrolysis pretreatment caused the highest boost of enzymatic hydrolysis (eight-fold increase in sugar yields compared to control without any pretreatment). Moreover, this fungus provided 26.7% higher delignification than control during Kraft pulping and a higher refining degree during mechanical pulping (69° SR vs. 48° SR control). Chemical and mechanical pulps from fungal pretreatment also showed better physical properties than control pulps (increases in tensile, tear and burst indexes of 28.4%, 15.6% and 43.9%, respectively). Regarding biobleaching, after the enzymatic treatment and a hydrogen peroxide stage, a brightness increase (2.3 points %ISO) was obtained. CONCLUSIONS The potential of the endophytic fungal strain Hormonema sp. for biotechnological applications as fermentable sugars production, biopulping and biobleaching has been demonstrated. In this sense, this is the first study on the use of an endophytic fungus for a biobleaching sequence.