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Beckett R.P.,University of KwaZulu - Natal | Zavarzina A.G.,Moscow State University | Liers C.,Unit of Environmental Biotechnology
Fungal Biology

Lichens are symbiotic associations of a fungus (usually an Ascomycete) with green algae and/or a cyanobacterium. They dominate on 8% of the world's land surface, mainly in Arctic and Antarctic regions, tundra, high mountain elevations and as components of dryland crusts. In many ecosystems, lichens are the pioneers on the bare rock or soil following disturbance, presumably because of their tolerance to desiccation and high temperature. Lichens have long been recognized as agents of mineral weathering and fine-earth stabilization. Being dominant biomass producers in extreme environments they contribute to primary accumulation of soil organic matter. However, biochemical role of lichens in soil processes is unknown. Our recent research has demonstrated that Peltigeralean lichens contain redox enzymes which in free-living fungi participate in lignocellulose degradation and humification. Thus lichen enzymes may catalyse formation and degradation of soil organic matter, particularly in high-stress communities dominated by lower plants. In the present review we synthesize recently published data on lichen phenol oxidases, peroxidases, and cellulases and discuss their possible roles in lichen physiology and soil organic matter transformations. © 2013 The British Mycological Society. Source

Beckett R.P.,University of KwaZulu - Natal | Minibayeva F.V.,Russian Academy of Sciences | Liers C.,Unit of Environmental Biotechnology

Abstract In our earlier work, we demonstrated that the oxidases tyrosinase and laccase occur widely in lichens from the Peltigerales. Recently, we discovered the occurrence of another oxidoreductase, a heme peroxidase, in the Peltigeralean 'jelly lichens' Leptogium and Collema. Here we present the results of a survey of peroxidase activity in a range of lichens. In addition to the jelly lichens, strong peroxidase activity also occurs within the Peltigeralean genera Lobaria, Pseudocyphellaria and Sticta. Significant activity occurs in the cell wall, and, unlike laccase activity, peroxidase activity increases considerably following the rehydration of dry thalli. However, activity is absent from Peltigera and from the non-Peltigeralean species tested here. Electrophoretic investigation showed that lichen peroxidases are oligomeric. Possible roles for peroxidases in lichen biology are discussed. Copyright © British Lichen Society 2013. Source

Peng L.,University of Potsdam | Wollenberger U.,University of Potsdam | Hofrichter M.,Unit of Environmental Biotechnology | Ullrich R.,Unit of Environmental Biotechnology | And 3 more authors.
Electrochimica Acta

A biosensor for detecting the aromatic substance 4-nitrophenol based on Agrocybe aegerita peroxygenase (AaP) immobilized with chitosan-stabilized gold nanoparticles is presented here. This biosensor measures the enzymatic product of 4-nitrophenol peroxygenation, 4-nitrocatechol, which is electrochemically detected in the presence of hydrogen peroxide. Cyclic voltammetry and amperometry were used to characterize the proposed biosensor. The linear range of the AaP biosensor for the detection of 4-nitrophenol was between 10 and 30 μM with a detection limit of 0.2 μM (based on the S/N = 3). The catalytic property of AaP to oxidize 4-nitrophenol was compared with two other heme proteins, a camphor-hydroxylating cytochrome P450 monooxygenase (P450 cam, CYP101) and horseradish peroxidase (HRP). The results revealed that only AaP is capable of catalyzing the hydroxylation of 4-nitrophenol into 4-nitrocatechol. Consequently, AaP could be a particularly potent biocatalyst that may fill the gap between cytochrome P450s and common heme peroxidases. © 2010 Elsevier Ltd. All rights reserved. Source

Kabiersch G.,University of Helsinki | Rajasarkka J.,University of Helsinki | Ullrich R.,Unit of Environmental Biotechnology | Tuomela M.,University of Helsinki | And 4 more authors.

Bisphenol A is an endocrine disrupting compound, which is ubiquitous in the environment due to its wide use in plastic and resin production. Seven day old cultures of the litter-decomposing fungus Stropharia coronilla removed the estrogenic activity of bisphenol A (BPA) rapidly and enduringly. Treatment of BPA with purified neutral manganese peroxidase (MnP) from this fungus also resulted in 100% reduction of estrogenic activity, as analyzed using a bioluminescent yeast assay, and in the formation of polymeric compounds. In cultures of Stropharia rugosoannulata, estrogenic activity also quickly disappeared but temporarily re-emerged in the further course of cultivation. LC-MS analysis of the extracted estrogenic culture liquid revealed [M-H]- ions with m/z values of 219 and 235. We hypothesize that these compounds are ring fission products of BPA, which still exhibit one intact hydroxyphenyl group to interact with estrogen receptors displayed by the yeast. © 2011 Elsevier Ltd. Source

Gutierrez A.,CSIC - Institute of Natural Resources and Agriculture Biology of Seville | Babot E.D.,CSIC - Institute of Natural Resources and Agriculture Biology of Seville | Ullrich R.,Unit of Environmental Biotechnology | Hofrichter M.,Unit of Environmental Biotechnology | And 2 more authors.
Archives of Biochemistry and Biophysics

Reaction of fatty acids, fatty alcohols, alkanes, sterols, sterol esters and triglycerides with the so-called aromatic peroxygenase from Agrocybe aegerita was investigated using GC-MS. Regioselective hydroxylation of C 12-C20 saturated/unsaturated fatty acids was observed at the ω-1 and ω-2 positions (except myristoleic acid only forming the ω-2 derivative). Minor hydroxylation at ω and ω-3 to ω-5 positions was also observed. Further oxidized products were detected, including keto, dihydroxylated, keto-hydroxy and dicarboxylic fatty acids. Fatty alcohols also yielded hydroxy or keto derivatives of the corresponding fatty acid. Finally, alkanes gave, in addition to alcohols at positions 2 or 3, dihydroxylated derivatives at both sides of the molecule; and sterols showed side-chain hydroxylation. No derivatives were found for fatty acids esterified with sterols or forming triglycerides, but methyl esters were ω-1 or ω-2 hydroxylated. Reactions using H2 18O2 established that peroxide is the source of the oxygen introduced in aliphatic hydroxylations. These studies also indicated that oxidation of alcohols to carbonyl and carboxyl groups is produced by successive hydroxylations combined with one dehydration step. We conclude that the A. aegerita peroxygenase not only oxidizes aromatic compounds but also catalyzes the stepwise oxidation of aliphatic compounds by hydrogen peroxide, with different hydroxylated intermediates. © 2011 Elsevier Inc. All rights reserved. Source

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