Biodegradation aspects of Polycyclic Aromatic Hydrocarbons (PAHs): A review

Microbial degradation of hydrocarbons in the environment.

Mechanisms of membrane toxicity of hydrocarbons.

Dioxygen activation at mononuclear nonheme iron active sites: enzymes, models, and intermediates.

Food webs in nature have multiple, reticulate connections between a diversity of consumers and resources. Such complexity affects web dynamics: it first spreads the direct effects of consumption and productivity throughout the web rather than focusing them at particular "trophic levels." Second, consumer densities are often donor controlled with food from across the trophic spectrum, the herbivore and detrital channels, other habitats, life-history omnivory, and even trophic mutualism. Although consumers usually do not affect these resources, increased numbers often allow consumers to depress other resources to levels lower than if donor-controlled resources were absent. We propose that such donor-controlled and "multichannel" omnivory is a general feature of consumer control and central to food web dynamics. This observation is contrary to the normal practice of inferring dynamics by simplifying webs into a few linear "trophic levels," as per "green world" theories. Such theories do not accommodate commo...

Food Web Complexity and Community Dynamics

16 contributions by various authors. Degradative pathways. Chemical characterisation of biodegradation. C1 compounds transformation. Aliphatic compounds. Alcyclic rings. Aromatics hydrocarbons. Furans, tiophenes, halogenated aromatic compounds. Phtalates. Lignin. Significance of microbial communities. -- ICCROM

Microbial degradation of organic compounds.

A fragment of plasmid NAH7 from Pseudomonas putida PpG7 has been cloned and expressed in Escherichia coli HB101. Growth of the recombinant Escherichia coli in nutrient medium results in the formation of indigo. The production of this dye is increased in the presence of tryptophan or indole. Several bacteria that oxidize aromatic hydrocarbons to cis-dihydrodiols also oxidize indole to indigo. The results suggest that indigo formation is due to the combined activities of tryptophanase and naphthalene dioxygenase.

https://science.sciencemag.org/content/sci/222/4620/167.full.pdf

Expression of naphthalene oxidation genes in Escherichia coli results in the biosynthesis of indigo

Binding of oxygen to iron is exploited in several biological and chemical processes. Although computational and spectroscopic results have suggested side-on binding, only end-on binding of oxygen to iron has been observed in crystal structures. We have determined structures of naphthalene dioxygenase that show a molecular oxygen species bound to the mononuclear iron in a side-on fashion. In a complex with substrate and dioxygen, the dioxygen molecule is lined up for an attack on the double bond of the aromatic substrate. The structures reported here provide the basis for a reaction mechanism and for the high stereospecificity of the reaction catalyzed by naphthalene dioxygenase.

https://science.sciencemag.org/content/sci/299/5609/1039.full.pdf

David T. Gibson

Papers

Microbial degradation of organic compounds.

Expression of naphthalene oxidation genes in Escherichia coli results in the biosynthesis of indigo

Crystal structure of naphthalene dioxygenase: side-on binding of dioxygen to iron.

Oxidative degradation of aromatic hydrocarbons by microorganisms. I. Enzymatic formation of catechol from benzene.

Formation of (+)-cis-2,3-dihydroxy-1-methylcyclohexa-4,6-diene from toluene by Pseudomonas putida.