Biotransformation of Araucaria araucana lignans: solid-state fermentation with a naturally occurring Pleurotus ostreatus strain

Abstract

The effects of a naturally occurring Patagonian strain of the white-rot fungus Pleurotus ostreatus on Araucaria araucana wood lignans was evaluated. Lignans of colonized and non-colonized wood shavings and the activity of fungal ligninolytic enzymes were studied. Lignans were identified using gas chromatography with a mass spectrometry detector. Only eudesmin lignan resisted biological degradation. The highest laccase activity was 0.111 ± 0.067 IU.g^-1 dry matter substrate, which was reached after 60 days, whereas the highest manganese peroxidase (MnP) activity was 0.220 ± 0.109 IU.g^-1 dry matter substrate, which was reached after 25 days, when the fungus was grown in a solid-state culture on wood shavings. The degradation properties of this fungal strain may be useful for not only treating resinous wastes from the regional forest industry to produce biofuels but also improving paper production. Moreover, the capacity of this white-rot fungus to grow on resinous A. araucana materials as substrate suggests the possibility of using the wood shavings or sawdust of this and other conifers as a food source to culture P. ostreatus, an edible mushroom.

Key words
Araucaria; GC-MS; laccase; lignans; Pleurotus