Microtox® assay

Argese, E., C. Bettiol, A.V. Ghirardini, M. Fasolo, G. Giurin, and P.F. Ghetti. 1998. Comparison of in vitro submitochondrial particle and Microtox assays for determining the toxicity of organotin compounds. Environ. Toxicol. Chem. 17 1005-1012. 

Using a preemptive approach, Lebo et al. (2004) have shown that oleic acid and methyl oleate can be removed from triolein prior to use of the triolein in SPMDs (see Chapters 4 and 5). Dialysates from SPMDs prepared using triolein purified by the Lebo et al. (2004) method exhibited lower acute toxicity (Microtox assay) than SPMDs prepared with unpurified triolein. Also, the YES assay demonstrated that the purification method had removed all background estrogenic activity from SPMD extracts. Eor these reasons, the use of triolein purified by the method of Lebo et al. (2004) is standard for all SPMD studies conducted at CERC, USGS. Also, SPMDs with triolein purified by the Lebo et al. (2004) method are available from the commercial vendor upon request. 

There are a number of full-scale activated sludge plants that are in operation in countries such as the United States, Canada, and Finland, which treat effluents from Kraft, sulfite, TMP, CTMP, and newsprint mills [22]. SchneU et al. [70] reported the effectiveness of a conventional activated sludge process operating at an alkaline-peroxide mechanical pulping (APMP) plant at Malette Quebec, Canada. The full-scale plant achieved 74% reduction in filterable COD and nearly complete elimination of BOD5, resin acids, and fatty acids in the whole mill effluent. The treated effluent tested nontoxic as measured by a Microtox assay. Saunamaki [71] reported... 

Eggens M., Schipper C., Vethaak A. and Klamer H., Mutatox and Microtox assays in a pollution gradient along the Dutch coastal zone. International Symposium on New Microbiotests, 1998, Brno, Czech Republic s. ... 

Cash, G.G. (1998) Prediction of chemical toxicity to aquatic organisms ECOSAR vs. Microtox assay. Environ Toxicol Water Qual, 13, 211-216. 

D.L. Campbell, L.A. Lawton, K.A. Beattie and G.A. Codd, Comparative assessment of the specificity of the brine shrimp and Microtox assays to... 

Choi, K. and Meier, P.G. (2001) Toxicity evaluation of metal plating wastewater employing the Microtox assay a comparison with cladocerans and fish, Environmental Toxicology 16 (2), 136-141. 

Hankenson, K. and Schaeffer, D.J. (1991) Microtox assay of trinitrotoluene, diaminonitrotoluene, and dinitromethylaniline mixtures, Bulletin of Environmental Contamination and Toxicology 46(4), 550-553. 

Mowat, F.S. and Bundy, J.G. (2002) Experimental and mathematical/computational assessment of the acute toxicity of chemical mixtures from the Microtox assay, Advances in Environmental Research 6(4), 547-558. 

Pardos, M., Benninghoff, C., Thomas, R.L. and Khim-Heang, S. (1999b) Confirmation of elemental sulfur toxicity in the Microtox assay during organic extracts assessment of freshwater sediments, Environmental Toxicology and Chemistry 18 (2), 188-193. 

Vibrio fischeri, bacterial luminescence inhibition test or Microtox assay (DEVL34, 1998). 

The Microtox assay which measures light inhibition with the bacterium Vibrio fisheri is a well known and useful aquatic toxicity test (see Chapter 1, volume 1 of this book). As previously reported (Blaise et al., 1994) and based on our own experience, it appears more appropriate to determine 60 min IC50 for waste leachates, as opposed to 15 min or 30 min endpoints. IC50s measured after 60 min on MIOM leachates were clearly more sensitive and reproducible than those measured at 30 min and 15 min (Ferrari et ah, 1999). Since WASTOXHAS was applied on (poly)metallic matrices in this study, we also found it more suitable to use zinc sulphate as a reference toxicant to periodically verify the sensitivity of the Microtox bacterial light reagent. 

T I 1 r Tnmnniil 9ATI 1 1 risk compound I (TU) r Microtox assay ( (Simple expert judgment ... 

Renoux, A. Y., Millette, D., Tyagi, R. D. Samson, R. (1999). Detoxification offluorene, phenanthrene, carbazole and p-cresol in columns of aquifer sand as studied by the Microtox assay. Water Research, 33, 2045-52. 

Hoke, R.A., Giesy, J.P. and Kreis Jr, R.G. (1992) Sediment pore water toxicity identification in the lower Fox River and Green Bay, Wisconsin using the Microtox assay. Ecotoxicol. Environ. Saf, 23, 343-354. 

The OECD Daphnia spp acute immobilisation and reproduction tests. A mainstay in aquatic toxicity testing, Daphnia tests have been used also to evaluate the toxicity of contaminated groundwaters and leachates (Kross and Cherryholmes, 1992). As with any of the aquatic tests, the principal problem with the Daphnia test is the need to extract a suitable aqueous sample. This problem is illustrated by Kross and Cherryholmes (1992), who compared D. magna and Microtox assay results in leachates but found a poor correlation between the two methods. 

Transgenic bacterial biosensors. Systems such as the Microtox assay detailed earlier use the marine species Vibrio fischeri as the sensor. Because it uses a marine bacterium, Microtox must be conducted in saline solution, which is ecologically irrelevant for most soils. Because no naturally luminescent soil bacteria are known that could be used as an alternative, one solution is to fuse the genes responsible for bioluminescence into soil-dwelling strains using recombinant technology (Paton et al., 1997). Two approaches can be used ... 

L.R. Johnson, R. Davenport, H. Balbach, D.J. Schaeffer (1994). Near-ultraviolet light-enhancement of Microtox assays of trinitrotoluene and aminodinitrotoluenes. EcotoxicoL Environ. Saf., 27, 23-33. 

Campbell H. L. and B. A. Striebig Evaluation of N-Methylpyrrolidone and its oxidation products toxicity utilizing the Microtox assay, Environ. Sci. Technoi, 33 (1999) 11, 1926-1930. 

Aqueous extracts of cat s claw were tested for cytotoxicity in four in vitro bioassays using Chinese hamster ovary cells and bacterial cells (Santa Maria et al., 1997). Concentrations of 10, 20, 30, 40, 50, 75, and 100 mg/mL were used. The neutral protein assay (measures inhibition of cell growth), the total protein content assay, the tetrazolium assay (measures mitochondrial succinic dehydrogenase activity), and the microtox assay (measures inhibition of light output from a luminescent bacterium) showed no evidence of cytotoxicity. 

Bacterial bioassays have been also investigated to determine if they can provide simple routine methods for the analysis of cyanotoxins. The one that has received more attention is the Microtox bioluminescence assay, which indicates toxicity by a reduction of the light, emitted by the test bacterium (Photobacterium phosphoreum). Further analysis revealed that there is no correlation between response in the Microtox assay and cellular content of the known cyanotoxins [157]. 

In Table 15.2.2.4, the results of these comparisons with the results of the Rhizobium test are presented. The Rhizobium test correlates well with Microtox , Daphnia, and particularly well with the 20 samples in the IC50 test. The comparison of the Rhizobium assays with other published results has been examined in detail (Botsford, 2000a). The Rhizobium test has been compared with values from several laboratories for the Microtox assay and correlation coefficients have varied from 0.750 to 0.893 indicating the two methods provide comparable results. Four comparisons with values for Daphnia have provided correlation coefficients from 0.776 to 0.953 indicating that the Rhizobium assay agrees well withZJa/ / -nia. 

Escherichia coli Photohacterium phosphoreum (Microtox assay)... 

In Table 15.2.2.3 the results of comparisons among these tests are summarized. The data from these 6 determinations were plotted, one assay versus another assay, the regression coefficient noted and the correlation coefficient calculated. The Rhizobium assay was the most sensitive for 12 of 33 chemicals. The Microtox assay was most sensitive for 6 of the compounds. The 1C50 assay was most sensitive for 6 of the compoimds. The Daphnia test was most sensitive to 10 of the compoimds. The average values for the toxicity of the chemicals was lowest for the IC50, but then it was also the test with the fewest values included. 

The Microtox assay was used to monitor the decline in toxicity of die triclosan solutions as a fhnction of the electrolysis time. This test monitors die... 

In general, the acute toxicities (5 min exposure) as determined in the Microtox assay were relatively low. T-2 toxin was the most toxic of the four compounds tested, at each one of the three different temperatures, followed by HT-2, DAS and DON. At the standard test temperature (15° C), the EC50 values obtained after 5 mins of exposure were 150, 336, 812 and 6,720 mg L" for T-2, HT-2, DAS and DON, respectively. 

---