Microbial activity assay

In vitro activity assay (for pharmacological activity Activity of the metabolite toward the therapeutic target is determined in vitro with a purified sample. Sometimes, the 0.1-10 mg Mammalian or Microbial bioreactors... 

Matheson et al. (1978) reported the results of a battery of in vivo and in vitro assays to assess the genotoxicity of 1,1-dimethylhydrazine. Included were the Ames Salmonella microsome assay, a microbial suspension assay, mutation induction at the TK locus in L5178Y mouse lymphoma cells, stimulation of UDS in WI-38 cells, and a dominant lethal assay in mice. 1,1-Dimethylhydrazine was active in all of the tests except the dominant lethal assay. 

Three primary tests are incorporated in the health effects area. The microbial mutagenesis assay is based on the property of selected Salmonella typhimurium mutants to revert from a histidine requiring state to prototrophy due to exposre to various classes of mutagens. The test can detect nanogram quantities of mutagens and has been adapted to mimic some mammalian metabolic processes by the addition of a mammalian liver microsomal fraction. The test is used as a primary screen to determine the mutagenic activity of complex mixtures or component fractions. 

Lipase (Microbial) Activity for Medium- and Long-Chain Fatty Acids, (S3)105 Lysozyme Activity, (S3)106 Maltogenic Amylase Activity, 804 Milk-Clotting Activity, 805 Pancreatin Activity, 805 Pepsin Activity, 807 Phospholipase A2 Activity, 808 Phytase Activity, 808 Plant Proteolytic Activity, 810 Proteolytic Activity, Bacterial (PC), 811 Proteolytic Activity, Fungal (HUT), 812 Proteolytic Activity, Fungal (SAP), 813 Pullulanase Activity, 814 Trypsin Activity, 814 Enzyme Assays, 786 Enzyme-Hydrolyzed (Source) Protein,... 

Capone, D. G., and Carpenter, E. J. (1982b). A perfusion method for assaying microbial activities in estuarine sediments. Applicability to studies of N2 (C2H2) reduction. Appl. Environ. Microbiol. 43,... 

Figure 4 Structures of common microbial metabolites active in the macrophage activation assay...

Chander, K. and Brooks, P.C. (1991) Is the dehydrogenase assay invalid as a method to estimate microbial activity in copper-contaminated soils Soil Biology Biochemistry, 23, 909-915. 

EPTC and Butvlate Fluorescein Diacetate Assay. Spectrophotometric determinations of the hydrolysis of fluorescein diacetate have been shown to be simple, rapid, and sensitive methods for determining microbial activity in soil (18). Essentially, the hydrolytic cleavage of diacetate from fluorescein is responsible for the reaction products including fluorescein, which may be detected spectrophotometrically at 490 nm. This method is somewhat nonspecific in that it is indicative of overall activity of several enzymes (protease, lipase, esterase) rather than of a specific class of enzymes. Enzyme activity may be influenced by subtle pH changes in the sample since abiotic hydrolysis of fluorescein diacetate may occur. Also, an associated lag phase in soil hydrolytic activity must be accounted for in each assay. 

Washburn KS et al., A study of 2,4,6-trinitrotoluene inhibition of benzo[a]pyrene uptake and activation in a microbial mutagenicity assay, Chemosphere, 44,1703, 2001. 

Approximate ranges of subsurface bacterial biomass and metabolic activity from the literature are shown in Table II. There have been few studies of relative measures of biomass or activity at contaminated versus uncontaminated sites. It is clear that certain functional classes of bacteria appear to increase in organic-rich environments (11-121 There are substantial problems associated with determining microbial activity in contaminated environments due to the diversity of types of microorganisms and chemical interferences with assay procedure. 

Mercury is the only metal that remains liquid at normal temperatures. This makes it a rather volatile element and mercnry vapor is highly toxic. Air saturated with mercury vapor at 20° C has a mercury content one hundred times higher than the toxicity limit. Mercury ore, or cinnabar (HgS), is a lovely, red-colored snlfide. Mercnry stored in sediments is returned to the food chain via microbial activity that converts metallic mercury into organic mercury, in the form of highly toxic, volatile, methyl mercury. The toxicity of mercury gives it useful medical properties as an antiseptic and anti-parasitic. Mercury concentrations in wines are below 5 p.g/1. (Brun and Cayrol, 1976). It is not easy to assay mercury by atomic absorption, as the high pressure of mercury vapor means that the temperature cannot exceed 60°C when the wine is being mineralized. 

Enzyme assays are simple and serve as excellent indicators of microbial activities. They have also been used as indicators to evaluate nutrient/contaminant impacts in wetlands. However, there are several limitations to their use in quantitative evaluation of carbon and nutrient cycling in wetlands (Sinsabaugh et al., 1991). Some of the limitations are... 

Adenosine 5 -triphosphate (ATP) assay The functional significance of ATP in the metabolism of living cells suggests that its measurement should be an excellent monitor of microbial activity in the sample. There are two factors that adversely affect the estimation of bacterial numbers by measurement of ATP first, nonbacterial ATP and, second, quenching of the emitted light. Eailure to destroy the... 

Table 10.9 Inspection, Growth, and Activity Assays for Microbial Populations...

Sephadex LH-20 gel column with isopropanol followed by acetone. About 90% of the basic mutagenic activity is recovered in the acetone subfraction, which comprises approximately 0.5 wt% of the crude oil. Development of this separation scheme (Figure 5) was made possible by use of microbial mutagenesis assays as the detector during exploratory liquid chromatographic separations. Table 7 lists some of the preliminary data from these studies. 

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