María Isabel Fonseca

Copper inducing effect on laccase production of white rot fungi native from Misiones (Argentina)

Fungi may be selected as models for gene expression studies and further adaptation for biotechnological enzyme production. The aim of this work was to evaluate laccase production and to analyze the effect of Cu(2+) on selected fungi natives of Misiones, Ganoderma applanatum (strain F), Peniophora sp. (BAFC 633), Pycnoporus sanguineus (BAFC 2126) and Coriolus versicolor f. antarcticus (BAFC 266). Fungi secretion system of G. applanatum, Peniophora sp., P. sanguineus and C. versicolor f. antarcticus is sensitive to stimulation by copper. Biomass values of G. applanatum, Peniophora sp. and C. versicolor f. antarcticus did not show differences between treatments. P. sanguineus biomass underwent a dramatic growth inhibition with 1mM Cu(2+) and marked delay in growth with 0.5mM Cu(2+). Proteins were increased with copper in Peniophora sp., C. versicolor and G. applanatum. G. applanatum and Peniophora sp. reached the highest enzyme activity at 10th day equivalent to 49.2-fold and 19.7-fold higher than the control samples, respectively. Copper produced an increase of constitutive laccases in all fungi and an additional inducible isoenzyme in Peniophora sp., C. versicolor f. antarcticus and G. applanatum.

White Rot Fungi Laccases for Biotechnological Applications

White rot fungi have an enzymatic system producing oxidative and hydrolytic enzymes that act on the degradation of certain components of the cell wall. They can be applied in several technological processes, such as paper industry, bio-fuels and environmental pollution. Laccases are multi-copper enzymes of wide substrate specificity and high non-specific oxidation capacity that use molecular oxygen to oxidize various aromatic compounds, and are highly relevant biotechnological applications. In this review, we present some significant patents on laccase production and recombinant DNA technology for diverse biotechnology applications.

Screening of new secretory cellulases from different supernatants of white rot fungi from Misiones, Argentina

ABSTRACT Cellulases hydrolyse the cellulose chain into single sugars efficiently. These sugars can be fermented in the bioethanol process, a source of renewable energy. Misiones rainforest is one of the most biodiverse systems on the planet subtropical ecoregions, which is the most probable site to find new fungal strains with potential for degrading cellulose through cellulases. The aim of this work was to find an efficient cellulolytic microorganism through the exploration of native white rot fungi from Misiones. From the qualitative screening 11 fungal strains were selected. The quantitative analysis revealed that the isolated LBM 033 was the best cellulases producer, reaching 57, 226 and 387 U/l of cellobiohydrolase, β-glucosidase and endoglucanase activity, respectively. The zymograms showed that the molecular mass of most of the endoglucanases ranged from 69 to 88 kDa and the molecular mass of most of the cellobiohydrolases was 45 kDa. The search of new cellulases of secretory organisms should lead to an efficient degradation of cellulosic materials, and thus facilitating potential applications in the production of bioenergy from lignocellulosic biomass.

Preliminary studies of new strains of Trametes sp. from Argentina for laccase production ability

Oxidative enzymes secreted by white rot fungi can be applied in several technological processes within the paper industry, biofuel production and bioremediation. The discovery of native strains from the biodiverse Misiones (Argentina) forest can provide useful enzymes for biotechnological purposes. In this work, we evaluated the laccase and manganese peroxidase secretion abilities of four newly discovered strains of Trametes sp. that are native to Misiones. In addition, the copper response and optimal pH and temperature for laccase activity in culture supernatants were determined. The selected strains produced variable amounts of laccase and MnP; when Cu2+ was added, both enzymes were significantly increased. Zymograms showed that two isoenzymes were increased in all strains in the presence of Cu2+. Strain B showed the greatest response to Cu2+ addition, whereas strain A was more stable at the optimal temperature and pH. Strain A showed interesting potential for future biotechnological approaches due to the superior thermo-stability of its secreted enzymes.

Assessing the ability of white-rot fungi to tolerate polychlorinated biphenyls using predictive mycology

ABSTRACT The aim of the present study was to assess the ability of different white-rot fungi to tolerate polychlorinated biphenyls (PCBs) using predictive mycology, by relating fungal growth inhibition to ligninolityc enzyme secretion. Fungal strains were grown in the presence of PCBs in solid media and their radial growth values were modelled through the Dantigny-logistic like function in order to estimate the time required by the fungal colonies to attain half their maximum diameter. The principal component analysis (PCA) revealed an inverse correlation between strain tolerance to PCBs and the laccase secretion over time, being laccase production closely associated with fungal growth capacity. Finally, a PCA was run to regroup and split between resistant and sensitive fungi. Simultaneously, a function associated with a model predicting the tolerance to PCBs was developed. Some of the assayed isolates showed a promising capacity to be applied in PCB bioremediation. Abbreviations: Polychlorinated biphenyls (PCBs), white-rot fungi (WRF)

Isolation of a laccase-coding gene from the lignin-degrading fungus Phlebia brevispora BAFC 633 and heterologous expression in Pichia pastoris

Isolate and characterize a laccase‐encoding gene (lac I) of Phlebia brevispora BAFC 633, as well as cloning and expressing cDNA of lac I in Pichia pastoris. And to obtain a purified and characterized recombinant laccase to analyse the biotechnological application potential.