White rots

Fungi. Two forms of fungi commonly encountered are molds (filamentous forms) and yeasts (unicellular forms). Molds can be quite troublesome, causing white rot or brown rot of the cooling tower wood, depending on whether they are cellulolytic (attack cellulose) or lignin degrading. Yeasts are also cellulolytic. They can produce slime in abundant amounts and preferentially colonize wood surfaces. 

White rot fungus Fungus that attacks lignin, along with cellulose, and hemicellulose, leading to a marked lightening of the infected wood. 

Weiss-farber, m. bleacher, -faule, /. Bot.) white rot. -feuer, n. white fire, -fohre, /. Scotch pine Pinus sylvestris). 

White-rot fungus has been used as a biocatalyst for reduction and alkylation. The reaction of aromatic -keto nitriles with the white-rot fungus Curvularia lunata CECT 2130 in the presence of alcohols afforded alkylation-reduction reaction [291]. Alcohols such as ethanol, propanol, butanol, and isobutanol could be used (Figure 8.39d). 

The metabolic activity of other white-rot fungi including Phanerochaete chrysosporium and Pleurotus ostreacus has been discussed in the context of polycyclic aromatic hydrocarbons. For example, the mineralization potential of the manganese peroxide system fmmNematolomafrowardii for a number of substrates has been demonstrated (Hofrichter et al. 1998) the formation of CO2 from labeled substrates ranged from 7% (pyrene) to 36% (pentachlorophenol), 42% (2-amino-4, 6-dinitrotoluene), and 49% (catechol). 

Beaudette LA, S Davies, PM Fedorak, OP Ward, MA Pickard (1998) Comparsion of gas chromatography and mineralization experiments for measuring loss of selected polychlorobiphenyl congeners in cultures of white rot fungi. Appl Environ Microbiol 64 2020-2025. 

Bnmpus JA, SD Aust (1987) Biodegradation of DDT [l,Ll-trichloro-2,2-bis(4-chlorophenyl)ethane] by the white rot fungus Phanerochaete chrysosporium. Appl Environ Microbiol 53 2001-2008. 

Kennedy DW, SD Aust, JA Bumpus (1990) Comparative biodegradation of aUcyl halide insecticides by the white rot fungus, Phanerochaete chrysosporium (BKM-F-1767). Appl Environ Microbiol 56 2347-2353. Khanna P, B Rajkumar, N Jothikumar (1992) Anoxygenic degradation of aromatic substances by Rhodopseu-domonas palustris. Curr Microbiol 25 63-67. 

Mileski G, JA Bumpus, MA Jurek, SD Aust (1988) Biodegradation of pentachlorophenol by the white rot fungus, Phanerochaete chrysosporium. Appl Environ Microbiol 54 2885-2889. 

Yadav JS, RE Wallace, CA Reddy (1995) Mineralization of mono- and dichlorobenzenes and simultaneous degradation of chloro- and methyl-substituted benzenes by the white-rot fungus Phanerochaete chryso-sporium. Appl Environ Microbiol 61 677-680. 

Extracellnlar H2O2 is required for the activity of peroxidases in white-rot fungi, and this can be prodnced by several fungal reactions ... 

Bonnarme P, TW Jeffries (1990) Mn(ll) regulation of lignin peroxidases and manganese-dependent peroxidases from lignin-degrading white-rot fungi. Appl Environ Microbiol 56 210-217. 

Arjmand M, H Sandermann (1985) Mineralization of chloroaniline/lignin conjugates and of free chloroani-lines by the white rot fungus Phanerochaete chrysosporium. J Agric Pood Chem 33 1055-1060. 

The degradation of BTEX both individually or in admixture has been shown in a lignindegrading white-rot fungus under nonlignolytic conditions, and was confirmed with ring-labeled toluene (Yadav and Reddy 1993). Interest in fungal transformation of PAHs is noted in the next part of this chapter, and illustrative examples of the hydroxylation of monocyclic arenes include the following (Smith and Rosazza 1983) ... 

The mechanism and enzymology of transformations by white-rot fungi are complicated for several issues ... 

Although a number of white-rot fungi have been examined and shown to degrade PAHs (Field et al. 1992), greatest attention has probably been directed to Phanerochaete chrysosporium and Pleurotus ostreatus, and to the PAHs anthracene, phenanthrene, pyrene, and benzo[a]pyrene that will be used to illustrate the cardinal principles. A substantial fraction of PAHs may also be sorbed to the biomass—40% for phenanthrene and 22% for benzo[a]pyrene (Barclay et al. 1995). The degree of mineralization of PAHs by white-rot fungi may sometimes be quite low, for example, for Pleurotus ostreatus, yields were 3.0, 0.44, 0.19, and 0.19% for phenanthrene, pyrene, fluorene, and benzo[a]pyrene, respectively (Bezalel et al. 1996a). 

Bezalel L, Y Hadar, CE Cerniglia (1996a) Mineralization of polycyclic aromatic hydrocarbons by the white-rot fungus Pleurotus ostreatus. Appl Environ Microbiol 62 292-295. 

Field JA, E de Jong, GF Costa GF, JAM de Bont (1992) Biodegradation of polycyclic aromatic hydrocarbons by new isolates of white-rot fungi. Appl Environ Microbiol 58 2219-2226. 

Yadav JS, JF Quensen, JM Tiedje, CA Reddy (1995) Degradation of polychlorinated biphenyl mixtures (Aro-chlors 1242, 1254, 1260) by the white rot fungus Phanerochaete chrysosporium as evidenced by congener-specific analysis. Appl Environ Microbiol 61 2560-2565. 

The degradation of chlorinated phenols has been examined with the white-rot basidiomy-cete Phanerochaete chrysosporium under conditions of nitrogen limitation, and apparently involves both lignin peroxidase and manganese-dependent peroxidase activities (Valli and Gold 1991). 

Barr DP, SD Aust (1994) Mechanisms white rot fungi use to degrade pollutants. Environ Sci Technol 28 78A-87A. 

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