Mechanisms for polycyclic aromatic hydrocarbon degradation by ligninolytic fungi.

Abstract

Ligninolytic fungi accomplish the partial degradation of numerous aromatic organopollutants. Their ability to degrade polycyclic aromatic hydrocarbons (PAHs) is particularly interesting because eukaryotes were previously considered to be unable to cleave fused-ring aromatics. Recent results indicate that extracellular peroxidases of these fungi are responsible for the intitial oxidation of PAHs. Fungal lignin peroxidases oxidize certain PAHs directly, whereas fungal manganese peroxidases co-oxidize them indirectly during enzyme-mediated lipid peroxidation. -Environ Health Perspect 103(Suppl 5): 41-43 (1995) Key words: white-rot fungi, organopollutant degradation, lignin peroxidase, manganese peroxidaseThe ligninolytic fungi that cause white-rot of wood degrade a wide variety of organopollutants. The compounds metabolized include chlorophenols, chloroanilines, pesticides such as DDT and methoxychlor, and polycyclic aromatic hydrocarbons (1,2). To varying degrees, pollutants in these groups are co-oxidized by the fungi to give CO2 and largely uncharacterized polar metabolites. The xenobiotic oxidations of white-rot fungi are not rapid or efficient, but they are very nonspecific. Moreover, many white-rot fungi are natural inhabitants of soil litter. These considerations make ligninolytic fungi attractive candidates for use in low tech bioremediation programs (3). Little is known about the mechanisms that whiterot fungi employ for organopollutant oxidation.Xenobiotic metabolism in white-rot fungi usually parallels ligninolytic metabolism. Most recent work on ligninolysis has been done with a thermotolerant whiterotter, Phanerochaete chrysosporium, and we now have a fairly extensive understanding of this basidiomycete's ligninolytic mechanisms (4,5). Ligninolysis is oxidative, is stimulated by high oxygen levels in the culture medium, and is part of the organism's secondary metabolism; it occurs only when

Degradation of Anthracene by Alkaliphilic Bacteria Bacillus badius

“…The formation of anthrone was detected, which was an expected intermediate and it was followed by the appearance of 9, 10-anthraquinone. (Ceringlia, 1992) has been earlier described anthraqoinon as the common oxidation products, this data was in agreement with data published by (Hammel, 1995;Jin-Shao Ye., 2011) who has shown that anthracene inculcated with Aspergillus fumigates.…”

Xylans

“…This is not the case using fungal delignification using a variety of special white rot fungi which have been shown to replace 72% of the chemicals needed to bleach lu-aft pulp (Fujita et a/.,1991). Ligninolytic fungi which cause white rot of wood produce extracellular oxidative enzymes, the best characterized of which are laccase (polyphenol oxidase), lignin peroxidases (1 igninase) (LiP) and manganese peroxidases (MnPs) (Hammel et a/.,1995). White rot fungi (i.e Tranzetes versicolar) have been used successfully in the pre-treatment of thermomechanical, post-treatment of mechanical pulps and in the biobleaching of kraft pulps (Paice et a/.,1995).…”

Polyacrylamide Gel Electrophoresis an Important Tool for the Detection and Analysis of Enzymatic Activities by Electrophoretic Zymograms

“…In the case of NADP + -dependent trans-dihydrodiol dehydrogenases, almost all investigations have been done in mammalian tissues (Carbone et al, 2008;Chang et al, 2009;Chen et al, 2008) but only a few reports about these important enzymes have been done in fungi (Bezalel et al, 1997;Hammel, 1995;Sutherland et al, 1993) particularly in Phanerochaete chrisosporium (Bogan & Lamar, 1996;Muheim et al, 1991). At date, there is no any report about the detection of dihydrodiol dehydrogenase activities by means of electrophoretic zymograms in any organism.…”