Microorganisms, metabolism

Microorganisms are considered to be one of the most significant factors in the degradation and eventual elimination of pesticides and other xenobiotics in the environment. Such a conclusion has been well supported by many documents published during the last two decades. It is also well known that microorganisms metabolize xenobiotics mainly by oxidative, hydrolytic, reductive, and isomerization processes (1). ... 

In an in vitro fermentation study, rumen microorganisms metabolized both isomers of [ C]DDT o,p- and p,p-) to the corresponding DDD isomers at a rate of 12%/h. With p,//-DDT, 11% of the C detected was an unidentified polar product associated with microbial and substrate residues (Fries et al., 1969). In another in vitro study, extracts of Hydrogenomonas sp. cultures degraded DDT to DDD, l-chloro-2,2-bis(/5-chlorophenyl)ethane (DDMS), DBF, and several other products under anaerobic conditions. Under aerobic conditions containing whole cells, one of the rings is cleaved and p-chlorophenylacetic acid is formed (Pfaender and Alexander, 1972). 

Unknown important responses are destructive in many systems chemical plant explosions caused by impurity built up in reactors Minimata disease, the result of microorganisms metabolizing inorganic mercury and passing it up the food chain the dust bowl of the 1930 s - all are examples of important system responses that were initially unknown and unsuspected [Adams (1991)]. 

Figure 1. Methods of MCA Direct calorimetry by microorganism metabolism of samples for analysis stripping by microorganism binding of interfering compounds.

Their antibacterial and mutagenic activity is closely related to the reduction of the 5-nitro group, which is common to all nitroimidazole drugs, and the subsequent formation of reactive metabolites that bind to bacterial DNA, inhibiting DNA and protein synthesis in the microorganisms. Metabolism of 5-nitroimidaz-oles in mammals usually leads to covalently bound residues with a persistent imidazole structure. 

Soil microorganisms metabolize the organophosphorus compounds fairly rapidly. In general, the drier the soil is, the slower the rate of... 

Reviews of the sulfur cycle from a biogeochemical or microbiological perspective have recently been presented, e.g. by Amend et al. (2004) and Canfield et al. (2005). The latter authors describe the relationship between the different microorganisms metabolizing sulfur compounds and their environment and emphasize the organisms as well as the biogeochemical processes. 

Earlier reports show that microorganisms metabolize diazinon either in the presence of additional carbon source (2, 17, 23, 27, 28) or syner-gistically by the action of two microorganisms (24). Bacteria capable of degrading diazinon are listed in Table V. These studies show clearly that attempts to isolate a bacterium utilizing diazinon as sole carbon source have been unsuccessful. In this report, using a maximum dilution-frequency technique, we have succeeded in isolating a Flavobacterium sp. from paddy water of diazinon-treated fields that could metabolize diazinon as sole carbon source. 

Microorganisms metabolically engineered with improved inhibitor tolerance could reduce the need for detoxification process. Larsson et al. (766) developed a S. cerevisiae strain with enhanced resistance to phenolic fermentation inhibitors in lignocellulose hydrolyzates by heterologous expression of laccase. 

Naturally, a biofilm develops on the membrane surface contacting the biological compartment. This biofilm acts as an active reaction zone, where most of the aimed reaction process takes place, also providing an additional barrier to the transport of excess carbon source, used as electron donor, from the biomedium to the treated water. These three features assure that secondary contamination of treated water by microorganisms, metabolic by-products and excess carbon source can be avoided if an appropriate membrane and operating conditions are selected. Also, strict control of the rate of addition of carbon source, aiming to avoid a situation of excess or deprivation, is not required. 

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