Biodegradation microbial processes

As a result of the highly reduced state of petroleum hydrocarbons, the preferred and most thermodynamically terminal electron acceptor for microbial processes is oxygen. The inverse relationship between the concentrations of BTEX and dissolved oxygen within a plume is indicative of the extent of microbial metabolism of this class of contaminant. Data from various sites indicate that the natural attenuation of BTEX proceeds at higher rates under oxygenated conditions. The biodegradation of... 

Field J.A. (2003). Biodegradation of Chlorinated Compounds by White Rot Fungi. In M.M. Haggblom and I.D. Bossert (Eds.). Dehalogenation Microbial Processes and Environmental Applications. Kluwer Academic, pp. 159-204. 

The interaction of bacteria with solid surfaces including soil may have a variety of indirect and direct impacts on the cell (van Loosdrecht et al., 1990). Direct impacts result from changes in microbial membranes (e.g., permeability to various substrates) resulting from a surface interaction. Indirect impacts related to microbial activity are a result of modification of the immediate environment of the cell (e.g., alteration of substrate availability) (Harms Zehnder, 1994). The influences of soil colloids on general microbial processes (Stotzky, 1986) and biodegradation kinetics of organic contaminants (Scow, 1993) have been summarized. However, two areas specifically pertinent to bioremediation will be described. 

Some of the first studies on the biodegradation of sulfur compounds focused on their fate and removal from oil-contaminated environments. Another major area of study is the microbial process of "biodesulfurization" which has been suggested as a means of selectively removing sulfur compounds from petroleum prior to refining. Information gathered from these two areas of research provide the basis of the present knowledge of metabolism of organosulfur compounds in petroleum. This information is reviewed with emphasis on the metabolism of dibenzothiophenes and n-alkyl tetrahydrothiophenes (n-alkyl thiolanes). 

A simple use of mass-balance considerations that shows this net transformation of chlorinated ethenes is the observed accumulation of chloride in contaminant plumes. For example, in a study of a large plume of TCE-contaminated groundwater at Dover Air Force Base, Delaware, Witt et al. (2002) showed that the concentration of chloride increased as TCE concentrations decreased, suggesting the net transformation of the chlorine in TCE to chloride. This chloride tracer of chlorinated ethene biodegradation is of use for mass-balance calculations to demonstrate biodegradation processes in the held. These held observations formed the basis of experimental studies under controlled laboratory conditions that documented the many and varied microbial processes that transform and destroy chlorinated ethenes in groundwater systems. 

Contents indude metabolic processes, microbial processes, biodegradation and bioaccumulation, aquatic and soil biochemistry, organometallics, inorganic and organic toxic compounds, and toxic natural products. 

Microbial Synthesis of Biodegradable Polyesters Processes, Products, Applications... 

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