Bioremediation of high molecular weight polycyclic aromatic hydrocarbons: a review of the microbial degradation of benzo[a]pyrene.

Publisher Summary This chapter deals with the microbial transformation of polycyclic aromatic hydrocarbons (PAHs) The similarities and differences between the microbial and mammalian metabolism are described Bacteria, filamentous fungi, yeasts, cyanobacteria, diatoms, and other eukaryotic algae have the enzymatic capacity to oxidize PAHs that range in size from naphthalene to benzo[ a ]pyrene The hydroxylation of PAHs always involves the incorporation of molecular oxygen; however, there are differences in the mechanism of hydroxylation of PAHs by prokaryotic and eukaryotic microorganisms Bacteria oxygenate PAHs to form a dihydrodiol with a cis configuration The genes for the initial oxidation of PAHs are localized on plasmids In contrast to bacteria, fungi oxidize PAHs via a cytochrome P-450 monooxygenase to form arene oxide, which can isomerize to phenols or undergo enzymatic hydration to yield trans-dihydrodiols Multiple oxidative pathways may be involved in the cyanobacterial metabolism of PAHs Studies on PAH metabolism are entering a new era; biochemical genetic techniques such as gene cloning and transposon mutagenesis will provide new insight into the biochemistry and regulation of PAH degradative pathways

Microbial metabolism of polycyclic aromatic hydrocarbons.

The biodegradation of polycyclic aromatic hydrocarbons (PAH) often is limited by low water solubility and dissolution rate. Nonionic surfactants and sodium dodecyl sulfate increased the concentration of PAH in the water phase because of solubilization. The degradation of PAH was inhibited by sodium dodecyl sulfate because this surfactant was preferred as a growth substrate. Growth of mixed cultures with phenanthrene and fluoranthene solubilized by a nonionic surfactant prior to inoculation was exponential, indicating a high bioavailability of the solubilized hydrocarbons. Nonionic surfactants of the alkylethoxylate type and the alkylphenolethoxylate type with an average ethoxylate chain length of 9 to 12 monomers were toxic to a PAH-degrading Mycobacterium sp. and to several PAH-degrading mixed cultures. Toxicity of the surfactants decreased with increasing hydrophilicity, i.e., with increasing ethoxylate chain length. Nontoxic surfactants enhanced the degradation of fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.

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Degradation of polycyclic aromatic hydrocarbons in the presence of synthetic surfactants.

Preface. 1. Introduction. 1.1 Fungal Biodegradation and Biodeterioration. 1.2 How a Fungus Escapes Water to Grow in Air? 1.3 Fungal Morphology, Analysis and Growth Measurement. 1.4 Mass Transfer, Growth Kinetics, and Bioreactors. 1.5 Methods for Detection of Degradative Fungi. 1.6 Fungi as Environmental Indicators. 1.7 Fungal Attack on Coal. 1.8 Thermophilic, Alpine, and Lichen-Forming Fungi. 1.9 Mycoremediation: Fungal Bioremediation. 1.10 Ecology of Mycoremediation. 1.11 Genetic Engineering of Mycoremediation References. 2. Fungal Treatment of Industrial Wastewaters. 2.1 Introduction. 2.2 Alternative Industrial Wastewater Bioreactors. 2.3 Fungal Treatment of Industrial Wastewaters. 2.4 Biotechnology. 2.5 Conclusions and Future Perspectives References. 3. Fungal Treatment of Distillery and Brewery Wastes. 3.1 Introduction. 3.2 Composition and Characteristics of Stillage. 3.3 Alternative Industrial Stillage Treatment Reactors. 3.4 Fungal Treatment of Distillery and Brewery Wastes. 3.5 Fungal Fermentation and Decolorization. 3.6 Molasses Toxicity to Fungi. 3.7 Factors Affecting Fungal Fermentation and Decolorization. 3.8 Mechanisms of Melanoidin Degradation. 3.9 Fungal Bioreactors for Distillery and Brewery Wastes. 3.10 Modeling. 3.11 Economic Importance. 3.12 Biotechnology. 3.13 Conclusions and Future Perspectives References. 4. Fungal Metabolism of Petroleum Hydrocarbons. 4.1 Introduction. 4.2 Fate of Oil in the Environment. 4.3 Composition of Petroleum Hydrocarbons. 4.4 Methods of Analysis of Petroleum Hydrocarbons. 4.5 Alternative Treatment Technologies. 4.6 Hydrocarbon-Utilizing Yeasts and Fungi. 4.7 Fungal Methods for Assessment. 4.8 Hydrocarbon Metabolism by Yeasts and Fungi. 4.9 Taxonomic Relationship of Hydrocarbon-Utilizing Yeasts and Fungi. 4.10 Factors Affecting Metabolism of Petroleum Hydrocarbons. 4.11 Fungal Mechanisms of Metabolism of Petroleum Hydrocarbons. 4.12 Oxidation of Petroleum Hydrocarbons by Fungal Enzymes. 4.13 Cytochrome P450 Enzyme Systems. 4.14 Economic Importance. 4.15 Biotechnology and Bioengineering. 4.16 Conclusions and Future Perspectives References. 5. Fungal Degradation of Polychlorinated Biphenyls and Dioxins. 5.1 Introduction. 5.2 Nomenclature. 5.3 Bioaccumulation and Toxicity. 5.4 Alternative PCB Remediation Technologies. 5.5 Analysis of Polychlorinated Biphenyls. 5.6 Bioavailability of Polychlorinated Biphenyls. 5.7 Fungal Degradation of Polychlorinated Biphenyls. 5.8 Fungal Degradation of Dioxins. 5.9 Genetic Manipulation. 5.10 Conclusions and Future Perspectives References. 6. Fungal Degradation of Pesticides. 6.1 Introduction. 6.2 Classification. 6.3 Biosensors for Detection of Pesticides. 6.4 Fungal Degradation of Insecticides. 6.5 Fungal Degradation of Herbicides. 6.6 Fungal Degradation of Fungicides. 6.7 Biotransformation of Pesticides by Fungal Enzymes. 6.8 Genetic Manipulation. 6.9 Conclusions and Future Perspectives References. 7. Fungal Metabolism of Phenols, Chlorophenols and Pentachlorophenol. 7.1 Introduction. 7.2 Alternative Treatment Technologies. 7.3 Fungal Biosensors for Determination of Various Types of Phenols. 7.4 Methods of Analysis of Various Types of Phenols. 7.5 Fungal Bioreactors for Removal of Various Types of Phenols. 7.6 Fungal Metabolism of Phenols, Chlorophenols and Pentachlorophenol. 7.7 Factors Affecting Fungal Metabolism of Various Types of Phenols. 7.8 Physiological Alterations of Fungi by Phenols. 7.9 Taxonomic Relationship of Phenol-Utilizing Yeasts and Fungi. 7.10 Mechanisms of Metabolism, Metabolic Pathways, and Metabolites. 7.11 Degradation of Phenols by Fungal Enzymes. 7.12 Fungal Transformation of Pentachlorophenol in Soils. 7.13 Cytochrome P450 Systems in Degradation of Phenols. 7.14 Conclusions and Future Perspectives References. 8. Fungal Metabolism of Polycyclic Aromatic Hydrocarbons. 8.1 Introduction. 8.2 Occurrence of PAHs in the Environment. 8.3 Alternative PAH Metabolism. 8.4 Fungal Metabolism of PAHs. 8.5 Mutagenicity of Fungal Metabolites of PAHs. 8.6 Fungal Bioreactors for Removal of PAHs. 8.7 PAH Degradation by Fungal Enzymes. 8.8 Cytochrome P450 in Degradation of PAHs. 8.9 Fungal Degradation of PAHs in Soils. 8.10 Fungal Metabolism of Complex PAH Mixtures. 8.11 PAH Degradation by Fungal-Bacterial Co-cultures. 8.12 Biotechnology and Bioengineering. 8.13 Conclusions and Future Perspectives References. 9. Fungal Lignin Degradation and Decolorization of Pulp and Paper Mill Effluents. 9.1 Introduction. 9.2 Distribution and Structure of Lignin. 9.3 Lignin-Degrading Microorganisms. 9.4 Fungal Lignin-Degrading Enzymes. 9.5 Mechanisms of Fungal Lignin Degradation and Metabolic Products. 9.6 Fungal Decolorization of Pulp and Paper Mill Effluents. 9.7 Fungal Bioreactors for Decolorization of Pulp and Paper Mill Effluents. 9.8 Factors Affecting Decolorization of Pulp and Paper Mill Effluents. 9.9 Effect of Fungal Treatment on Chlorophenols and Chloroaldehydes in Effluents. 9.10 Decolorization of Effluents by Fungal Enzymes. 9.11 Wetlands Treatment. 9.12 Conclusions and Future Perspectives References. 10. Fungal Decolorization and Degradation of Dyes. 10.1 Introduction. 10.2 Classification, Structure, and Color Measurements. 10.3 Legislation and Regulations. 10.4 Alternative Decolorization Treatment Technologies. 10.5 Fungal Decolorization and Degradation of Dyes. 10.6 Yeast Decolorization and Degradation of Dyes. 10.7 White-Rot Fungal Decolorization and Degradation of Dyes. 10.8 Mechanisms of Fungal Decolorization and Degradation of Dyes. 10.9 Metabolic Products and Pathways. 10.10 Factors Affecting Fungal Decolorization and Degradation of Dyes. 10.11 Fungal Dye Decolorization and Degradation Bioreactors. 10.12 Decolorization and Degradation of Dyes by Fungal enzymes. 10.13 Decolorization of Artificial Textile Effluent. 10.14 Sequential Dye Decolorization. 10.15 Conclusions and Future Perspectives References. 11. Fungal Biosorption of Heavy Metals. 11.1 Introduction. 11.2 Biosorption and Bioaccumulation of Heavy Metals. 11.3 Evaluation of Sorption Performance. 11.4 Mechanisms of Fungal Biosorption of Heavy Metals. 11.5 Fungal Biosorption Reactors for Heavy Metals. 11.6 Applications of Fungal Biosorption of Heavy Metals. 11.7 Fungal Biosorption of Herbicides and Phenols. 11.8 Fungal Biosorption of Dyes. 11.9 Fungal Binary and Ternary Biosorption Systems. 11.10 Biosorption of Heavy Metal Anions. 11.11 Metal Ion Resistance. 11.12 Conclusions and Future Perspectives References. 12. Mycorrhizal Fungi in Rhizosphere Remediation. 12.1 Introduction. 12.2 Classification of Mycorrhizal Fungi. 12.3 Functions of Mycorrhizal Mycelium. 12.4 Methods for Studying Mycorrhizal Fungi. 12.5 Molecular Mechanisms of Mycorrhizal Symbiosis. 12.6 Metabolism of Mycorrhizal Fungi. 12.7 Uptake of Toxic Metals. 12.8 Petroleum Hydrocarbon Degradation. 12.9 Lignin and Phenolic Degradation. 12.10 PAH and TNT Degradation. 12.11 PCB Degradation. 12.12 Herbicide Degradation. 12.13 Comparison of Mycorrhizal and White-Rot Fungi. 12.14 Conclusions and Future Perspectives References. Index.

Mycoremediation: Fungal Bioremediation

A Mycobacterium sp., designated strain BG1, able to utilize the polycyclic aromatic hydrocarbon phenanthrene as the sole carbon and energy source was isolated from estuarine sediment following enrichment with the hydrocarbon. Unlike other phenanthrene degraders, this bacterium degraded phenanthrene via 1-hydroxy-2-naphthoic acid without accumulating this or other aromatic intermediates, as shown by high-performance liquid chromatography. Degradation proceeded via meta cleavage of protocatechuic acid. Different nonionic surfactants (Tween compounds) solubilized the phenanthrene to different degrees and enhanced phenanthrene utilization. The order of enhancement, however, did not correlate perfectly with increased solubility, suggesting physiological as well as physicochemical effects of the surfactants. Plasmids of approximately 21, 58, and 77 megadaltons were detected in cells grown with phenanthrene but not in those which, after growth on nutrient media, lost the phenanthrene-degrading phenotype. Given that plasmid-mediated degradations of aromatic hydrocarbons generally occur via meta cleavages, it is of interest that the addition of pyruvate, a product of meta cleavage, supported rapid mineralization of phenanthrene in broth culture; succinate, a product of ortho cleavage, supported growth but completely repressed the utilization of phenanthrene. The involvement of plasmids may have given rise to the unusual degradation pattern that was observed.

Mineralization of phenanthrene by a Mycobacterium sp.

Of 15 species of fungi examined for their ability to hydroxylate biphenyl, 10 produced 4-hydroxybiphenyl. Seven of the 10 also produced 4,4′-dihydroxybiphenyl. The most efficient strains, Absidia pseudocylindrospora NRRL 2770 and Absidia sp. NRRL 1341, were more closely examined to determine their growth characteristics and the kinetics of biphenyl hydroxylation in batch fermentation. In the absence of biphenyl, A. pseudocylindrospora 2770 and Absidia sp. 1341 grew about as rapidly and efficiently in a defined glucose minimal medium as in a complex medium. Substrate yield coefficients for glucose in both media were 0.4 to 0.5 g of biomass per g of glucose, and the specific growth rate was about 0.17 h−1 (doubling time, about 4 h). In this unoptimized system, 10 to 15 g of biomass per liter (dry weight) could be produced, using a defined salt solution and glucose as sole carbon and energy source. In the presence of biphenyl, growth was inhibited, more so for strain 1341 than for strain 2770. However, the specific activity for biphenyl hydroxylation (milligrams of biphenol per gram of biomass) was about 3.5 times greater for strain 1341. Furthermore, biphenyl hydroxylation appeared to require the presence of an oxidizable carbon and energy source (and perhaps growth) to proceed and, at least for strain 1341, hydroxylation seemed to be more efficient in the complex medium.

Microbial production of 4,4'-dihydroxybiphenyl: biphenyl hydroxylation by fungi.

A biological process for converting naphthalene to cis-1,2-dihydroxy-1,2-dihydronaphthalene (DHD) catalyzed by Pseudomonas putida strain 119 was optimized in flask experiments. These studies revealed the following: (i) P. putida 119 can propagate efficiently and produce DHD when supplied one of several carbon sources and naphthalene; (ii) maximum DHD production by P. putida 119 occurs in logarithmic-growth-phase cells and decreases at various rates in the stationary growth phase, depending upon the carbon source used; (iii) several analogs of salicylic acid can be used as effective inducers of naphthalene metabolism in P. putida cells growing on glucose; and (iv) the addition of chemical surfactants to naphthalene-cell (P. putida 119) mixtures stimulates DHD production.

A. L. Williams

Papers

Microbial production of 4,4'-dihydroxybiphenyl: biphenyl hydroxylation by fungi.

Biological Process for Converting Naphthalene to cis-1,2-Dihydroxy-1,2-Dihydronaphthalene