Microbial processes composition

Even though substrate quality (i.e., chemical composition) is widely believed to be an important factor influencing microbial utilization of DOM, there are relatively few studies relating the composition and bioavailability of DOM. Sensitive assays for the measurement of the relative activities of various extracellular enzymes can provide an indication of the chemical composition of the bioreactive components of DOM (Sinsabaugh and Findlay, 1995 Findlay et al., 1998). The enzymatic potential of bacterial populations appears to respond fairly rapidly to seasonal changes in DOM composition in the Hudson River system. These observations clearly indicate that the chemical composition of DOM influences the microbial processing of DOM. 

The first step in the formation of coal is the alteration of plant material into peat by biochemical (i.e., microbial) processes. The overall properties and composition of a given peat depend upon the environmental conditions that existed during the alteration period after burial. During the biochemical stage, microorganisms can reduce the sulfate in saline pore water to an active form of sulfur, e.g., H2S. H2S will react with components of the sediment, forming pyrite when iron is present and forming... 

Inside a landfill leachate plume the environment is characterized by the presence of reduced species and high concentrations of dissolved organic matter. This environment is partly due to the composition of the leachate from the landfill and partly due to microbial processes in the plume. Since this environment is very different from that of uncontaminated, oligotrophic, often aerobic aquifers surrounding the plume, the composition of the microbial population of the plume is dramatically different from the indigenous microbial population of the uncontaminated aquifer. 

Coleman, M. (1993) Microbial processes controls on the shape and composition of carbonate concretions. Mar. Geol., 113, 127-140. 

The escape of natural gas from the gas distribution networks also exerts a considerable effect on physical, chemical and biological processes in the soil. The extent of the gas zone depends greatly on the rate of its escape, depth of the groundwater level, type of pipeline, the nature and moisture of the soil, treatment of its surface, etc. The composition of the gaseous phase in the soil is affected by the microbiological oxidation of methane. The rate of this depends on the soil temperature, presence of oxygen and the content of nutrients. At low temperatures, this microbial process is restricted, which also restricts the anaerobic zone. 

Ogram, A., S. Bridgham, R. Corstanje, H. Drake, K. Kosel, A. Mills, S. Newman, K. Portier, and R. Wetzel. 2006. Linkages between microbial community composition and biogeochemical processes across scales. Ecol. Studies 190 239-268. 

The temperature that maximizes the rate of many microbial processes is known to vary with medium composition. As a result, the operating temperature of biological reactors should be varied to keep such process rates maximal as their chemical milieux vary. 

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