Xenobiotic compounds cultures

Various natural and xenobiotic compounds have been studied for their ability to be the sole support of growth for microorganisms (Table 17.6). Sometimes enrichments simply isolate a pre-existing subpopulation of bacteria from the mixture of organisms present in a natural sample however, other times a mutation must occur which permits survival on the chemical provided (e.g., Brunner et al., 1980). From the data shown in Table 17.6, a few cautious generalizations can be made. First, maximum cell growth rates for acclimated cultures appear to correspond to doubling times of hours (recall... 

The use of plant cells or enzymes extracted from the cells for the biotransformation of exogenous substances offers another method for producing flavours. This would be useful when compounds are not found in cell suspensions. Many studies have been carried out on the biotransformation of xenobiotics or pharmaceuticals by plant cell culture [43, 50]. 

The main factors influencing CP remediation include temperature, the properties of the environmental matrix, the toxicity of CPs or other compounds, and the composition of indigenous or added microbial cultures (Crawford Mohn, 1985). Unlike many other xenobiotics, CPs undergo insignificant volatilization (Valo Salkinoja-Salonen, 1986 Lamar et al., 1990b Mueller et al., 1991a). The temperature, the contaminant bioavailability, the possible process amendments and the effects of additional contaminants are discussed below. 

Induction of CYP expression by xenobiotics has been reported in mainly three ways (1) induction potential (fold induction over control), (2) EC50 (effective concentration for 50% maximal induction), and (3) potency index (the ratio of induction response of the test compound compared to that of a gold standard). In our laboratory, we have defined CYP induction as a potency index or a percentage of a classic inducer rather than as fold increase over a control (induction potential). The reason for this is twofold. First, the basal levels of some CYPs may be low and therefore difficult to accurately quantitate. Second, we, and others, have found that basal CYP levels in culture may be highly... 

It also is possible to use intact ceils as a source of xenobiotic metabolizing enzymes. Activation for tissue culture systems can be provided by primary rat liver cells and irradiated hamster embryo cells which are plated as a feeder layer for the indicator cells. In the case of compounds which yield a spec-... 

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