Saprotrophic basidiomycete mycelia and their interspecific interactions affect the spatial distribution of extracellular enzymes in soil.

Saprotrophic cord-forming basidiomycetes are important decomposers of lignocellulosic substrates in soil. The production of extracellular hydrolytic enzymes was studied during the growth of two saprotrophic basidiomycetes, Hypholoma fasciculare and Phanerochaete velutina, across the surface of nonsterile soil microcosms, along with the effects of these basidiomycetes on fungi and bacteria within the soil. Higher activities of α-glucosidase, ß-glucosidase, cellobiohydrolase, ß-xylosidase, phosphomonoesterase and phosphodiesterase, but not of arylsulphatase, were recorded beneath the mycelia. Despite the fact that H. fasciculare, with exploitative hyphal growth, produced much denser hyphal cover on the soil surface than P. velutina, with explorative growth, both fungi produced similar amounts of extracellular enzymes. In the areas where the mycelia of H. fasciculare and P. velutina interacted, the activities of N-acetylglucosaminidase, α-glucosidase and phosphomonoesterase, the enzymes potentially involved in hyphal cell wall damage, and the utilization of compounds released from damaged hyphae of interacting fungi, were particularly increased. No significant differences in fungal biomass were observed between basidiomycete-colonized and noncolonized soil, but bacterial biomass was reduced in soil with H. fasciculare. The increases in the activities of ß-xylosidase, ß-glucosidase, phosphomonoesterase and cellobiohydrolase with increasing fungal:bacterial biomass ratio indicate the positive effects of fungal enzymes on nutrient release and bacterial abundance, which is reflected in the positive correlation of bacterial and fungal biomass content.

Influence of iron and copper nanoparticle powder on the production of lignocellulose degrading enzymes in the fungus Trametes versicolor.

White rot fungi are one of the key group of microorganisms that help to enrich the soil via degradation of wood. In the current communication, influence of iron and copper nanoparticles on the production of lignocellulolytic enzymes by Trametes versicolor have been investigated. The production of enzymes in the presence of the two nanoparticles was compared to that of ferrous and cupric ions respectively. Results show that both the tested nanoparticles alter the production profile of the lignocellulolytic enzymes when compared to the control set. The production of laccase was not influenced by iron nanoparticles but was effected by copper nanoparticles within 24h of incubation. Both the nanoparticles decreased the production of beta-glucosidase, beta-xylosidase and cellobiohydrolase significantly. However, the production profile of Mn-peroxidase and remained statistically similar to that of control when the organism was incubated with iron and copper nanoparticles. The production profiles were also different when one compares the ionic form of metals and the nanoparticles, suggesting different mechanism of action of the particles on the organism. The difference in the production profile was not growth related as no significant difference was recorded for either form of iron and copper on the growth of T. versicolor.