Application of White-Rot Fungi in Transformation, Detoxification, or Revalorization of Agriculture Wastes: Role of Laccase in the Processes

9 páginas, 3 figuras -- PAGS nros. 595-603In nature, an enormous quantity of lignocellulose material exists but only a small fraction is valorized, most remaining as waste. Promoting the principle of sustainable and environmentally friendly development, lignocellulose could be transformed through tailor-made biotechnological procedures into value-added natural products for use in animal feed or by the pharmaceutical, chemical, and biofuel industries. White-rot basidiomycetes have developed strategies to efficiently depolymerize and mineralize lignin, the barrier that protects cellulose and hemicellulose from microbial attack, and they represent a feasible option in the treatment of plant biomass and agricultural waste. The extracellular oxidoreductases, laccases, and peroxidases, secreted by these fungi play an essential role in the process. Although laccases have lower redox potential, the expanded role of these enzymes on nonphenolic compounds, in the presence of a low-molecular-mass mediator, as well as their utilization of oxygen, a nonlimited electron acceptor for their catalytic activity, makes them more suitable for industrial and environmental purposes. In this article, we discuss recent progress that has been made in employing white-rot basidiomycetous fungi in biotechnological applications for transforming agricultural waste, as well as for degrading recalcitrant compounds which cause environmental problems. We also focus on the role of laccases in the processes of revalorization, bioremediation, and detoxification of wastes and wastewaterThis work was supported by the Spanish projects S-0505/AMB0100 and CENIT I+DEA 2007/1031 and the Argentina grantsCONICET PIP 1422 and ANPCYT- BID 1728/OC-AR-PICT 2006 1219Peer reviewe

Transformation of the water soluble fraction from "alpeorujo" by Coriolopsis rigida: The role of laccase in the process and its impact on Azospirillum brasiliense survival.

The objective of this work was to evaluate the ability of the white rot basidiomycete Coriolopsis rigida to detoxify the water soluble fraction from "alpeorujo" (WSFA), a solid by-product produced by the olive oil extraction industry and characterized by a high concentration of phenols which limits its use as fertilizer and/or amendment. C. rigida reduced the phenol content in the liquid media supplemented with WSFA at 10 and 20% (v/v) after 15 d of incubation. The analysis of WSFA toxicity after fungal treatment showed that C. rigida was responsible for a significant increase in the survival rate of Azospirillum brasiliense, a N2 fixing soil rhizobacterium which promotes plant growth. Supplementation of culture medium with CuSO4 (300 μM) resulted in strong laccase induction thus facilitating higher phenol reduction and detoxification of WSFA. In vitro reactions using a crude extracellular preparation from laccase-active C. rigida showed phenol removal as well as detoxification of the WSFA at 20%. These results suggest that C. rigida reduces the phenol content of the WSFA through the effect of laccase on free phenolic compounds consequently decreasing the toxic effect on A. brasiliense, which suggests that the enzyme plays an important role in the process. These findings have implications in the management and revalorization of olive-mill residues treated with laccase-producing fungi and their potential impact on integrative agricultural systems including organic residues and the co-inoculation with microorganisms which can facilitate the growth of plants of agricultural interest.Saparrat M.C.N., researcher from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), thanks to Argentinean Government for grants (ANPCYT Préstamo BID 1728/OC-AR-PICT 2006 1219 and CONICET (PIP 1422). This research was partially supported by the Spanish project Ref. A/019945/08.Peer reviewe

Induction, Isolation, and Characterization of Two Laccases from the White Rot Basidiomycete Coriolopsis rigida

Previous work has shown that the white rot fungus Coriolopsis rigida degraded wheat straw lignin and both the aliphatic and aromatic fractions of crude oil from contaminated soils. To better understand these processes, we studied the enzymatic composition of the ligninolytic system of this fungus. Since laccase was the sole ligninolytic enzyme found, we paid attention to the oxidative capabilities of this enzyme that would allow its participation in the mentioned degradative processes. We purified two laccase isoenzymes to electrophoretic homogeneity from copper-induced cultures. Both enzymes are monomeric proteins, with the same molecular mass (66 kDa), isoelectric point (3.9), N-linked carbohydrate content (9%), pH optima of 3.0 on 2,6-dimethoxyphenol (DMP) and 2.5 on 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), absorption spectrum, and N-terminal amino acid sequence. They oxidized 4-anisidine and numerous phenolic compounds, including methoxyphenols, hydroquinones, and lignin-derived aldehydes and acids. Phenol red, an unusual substrate of laccase due to its high redox potential, was also oxidized. The highest enzyme affinity and efficiency were obtained with ABTS and, among phenolic compounds, with 2,6-dimethoxyhydroquinone (DBQH(2)). The presence of ABTS in the laccase reaction expanded the substrate range of C. rigida laccases to nonphenolic compounds and that of MBQH(2) extended the reactions catalyzed by these enzymes to the production of H(2)O(2), the oxidation of Mn(2+), the reduction of Fe(3+), and the generation of hydroxyl radicals. These results confirm the participation of laccase in the production of oxygen free radicals, suggesting novel uses of this enzyme in degradative processes

Insights into hydrocarbon assimilation by eurotialean and hypocrealean fungi Roles for CYP52 and CYP53 clans of cytochrome P450 genes

Several filamentous fungi are able to concomitantly assimilate both aliphatic and polycyclic aromatic hydrocarbons that are the biogenic by-products of some industrial processes. Cytochrome P450 monooxygenases catalyze the first oxidation reaction for both types of substrate. Among the cytochrome P450 (CYP) genes, the family CYP52 is implicated in the first hydroxylation step in alkane-assimilation processes, while genes belonging to the family CYP53 have been linked with oxidation of aromatic hydrocarbons. Here, we perform a comparative analysis of CYP genes belonging to clans CYP52 and CYP53 in Aspergillus niger, Beauveria bassiana, Metarhizium robertsii (formerly M. anisopliae var. anisopliae), and Penicillium chrysogenum. These species were able to assimilate n-hexadecane, n-octacosane, and phenanthrene, exhibiting a species-dependent modification in pH of the nutrient medium during this process. Modeling of the molecular docking of the hydrocarbons to the cytochrome P450 active site revealed that both phenanthrene and n-octacosane are energetically favored as substrates for the enzymes codified by genes belonging to both CYP52 and CYP53 clans, and thus appear to be involved in this oxidation step. Analyses of gene expression revealed that CYP53 members were significantly induced by phenanthrene in all species studied, but only CYP52X1 and CYP53A11 from B. bassiana were highly induced with n-alkanes. These findings suggest that the set of P450 enzymes involved in hydrocarbon assimilation by fungi is dependent on phylogeny and reveal distinct substrate and expression specificities.Fil: Huarte Bonnet, Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Kumar, Suresh. University Drive. Department of Diagnostic and Allied Health Sciences; MalasiaFil: Saparrat, Mario Carlos Nazareno. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Girotti, Juan Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Santana, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Hallsworth, John E.. The Queens University of Belfast; IrlandaFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; Argentin

Ligninolytic enzyme ability and potential biotechnology applications of the white-rot fungus Grammothele subargentea

8 páginas, 4 figuras, 2 tablas -- PAGS nros. 368-375To get a better insight into the ligninolytic system of Grammothele subargentea, extracellular ligninolytic enzyme activities and ability to degrade synthetic dyes as well as Eucalyptus globulus wood were assayed in cultures grown on an agar medium with Cu2+ or dyes and on E. globulus wood chips. Laccase was the only ligninolytic enzyme detected. The fungus was able to decolorize different dyes, being the highest levels of laccase activity in cultures with Brilliant Green. Cultures on wood showed both ligninolytic activity and degradative ability on lipophilic extractives. An extracellular laccase with pI 3.5 and maximal activity at pH 4.0 and 50–55 8C was detected on liquid cultures containing 0.6 mM Cu2+. The enzyme extract was stable at pH 6.0–7.0 and up to 60 8C. A laccase-mediator system using a G. subargentea laccase crude extract and 1- hydroxybenzotriazole as mediator improved the tensile strength of a paper from recycled high-kappa-number pulp. # 2008 Elsevier Ltd. All rights reservedThis work was supported by Fundacio´n Antorchas (Proy. 14188-64) Argentina, and Agencia Nacional de Promocio´n Cientı´fica y Tecnolo´gica (PICT 14- 06962, BID 1201/OC-AR, ANPCYT 13404 BID 1201/OCAR), Argentina.Peer reviewe