Determination of Pleurotus abieticola ligninolytic activity on Norway spruce wood

Abstract

Abstract The effect of Phlebiopsis gigantea treatment in control of Heterobasidion parviporum in Norway spruce is less effective than that in control of Heterobasidion annosum in pine. It is necessary to apply other fungi, for example, Pleurotus abieticola in Norway spruce stands. Thus, it is necessary to assess the activity of major ligninolytic enzymes, that is, laccase, lignin peroxidase (LiP), manganese peroxidase (MnP) and versatile peroxidase (VP) produced by P. abieticola, which may be effective in the fast degradation of Norway spruce wood. Three strains of P. abieticola (Pa1-3) were grown on pieces of Norway spruce sapwood and heartwood for 50 days in laboratory conditions. Enzymatic activity was determined using spectrophotometry. Pleurotus abieticola produced laccase, LiP, MnP and VP. The activity of laccase was low, ranging 0–3.696 and 0–0.806 mU/μg of protein in sapwood and heartwood, respectively. The highest activity in Pa1 = 3.696 mU/μg of protein in sapwood and in Pa3 = 0.806 mU/μg of protein in heartwood was observed after 30 and 50 days of incubation, respectively. The activity of LiP was also low, ranging 0–0.188 and 0–0.271 mU/μg of protein in sapwood and heartwood, respectively. The highest activity in Pa1 = 0.271 mU/μg of protein in sapwood and in Pa2 = 0.188 mU/μg of protein in heartwood was observed after 40 and 20 days of incubation, respectively. The activity of MnP ranged 0–17.618 and 0–12.203 mU/μg of protein in sapwood and heartwood, respectively. This enzymatic activity peaked at the 50th day of culture on sapwood for the Pa3 strain (17.618 mU/μg of protein) and at the 20th day of culture on heartwood for the Pa1 strain (12.203 mU/μg of protein). The activity of VP with manganese-oxidising properties was found to be high in all strains of P. abieticola, ranging 0–39.19 and 0–59.153 mU/μg of protein in sapwood and heartwood, respectively, whereas the activity of VP with guaiacol-oxidising properties was very low for all P. abieticola strains, ranging 0–0.248 and 0–0.225 mU/μg of protein in sapwood and heartwood, respectively. The values of released hydroxyphenols in P. abieticola strains ranged 24.915–139.766 and 25.19–84.562 µg of protocatechuic acid/ml in sapwood and heartwood, respectively. The values of released methoxyphenols for the evaluated strains of P. abieticola ranged 7.225–23.789 and 1.953–20.651 µg of vanillic acid/ml in sapwood and heartwood, respectively. Further studies with a higher number of strains of this species as well as an optimisation of conditions for the measurement of ligninolytic activity are needed.