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Toxicity to soil microorganisms

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Data have beenn obtained fron secondary source that include several pubblications.
PERIPLASMIC NITRATE REDUCTASE ACTIVITY FOR 2,4-DINITROPHENOL
Periplasmic nitrate reductase (NAP) activity was expressed relative to the amount of nitrite formed.
Median inhibitory concentration IC50 (mg/l) nitrate reductase activity: 45 .62 (R2 0.999).
PERIPLASMIC NITRATE REDUCTASE ACTIVITY FOR 2,4-DINITROPHENOL
The amount of formazan produced was determined by reference to a standard dose-response curve. Dehydrogenase activity (DHA) was expressed as milligrams of TPF formed per mg dry weight of cell biomass per hour.
Median inhibitory concentration IC50 (mg/l) nitrate reductase activity: > 200 (2,4-Dinitrophenol was stimulatory to dehydrogenase activity all concentrations studied).
Other observations during biodegradation in soil and sediment tests with observation of the toxicity lever for microorganisms defined that above the level of c.a 100 mg/L, 2,4 -dinitrophenol may be toxic to the degrader microorganisms (Bartha et al. 1967; Namkoong et al. 1988; Schmidt and Gier 1989).

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2,4-Dinitrophenol showed decreasing progressive stimulation of dehydrogenase enzyme with increasing concentration (40 – 200 mg/l) while 2-nitrophenol, 4-nitrophenol and 4-bromophenol showed increasing progressive inhibition of both enzyme activities. The IC50 of the phenolic compounds to the periplasmic nitrate reductase activity were comparable (33.46 – 44.75 mg/l) but lower than those for the dehydrogenase activity (>200 mg/l). This suggested greater sensitivity of periplasmic nitrate reductase than dehydrogenase enzyme to the phenolic compounds (

J. C. Okolo*, C. O. Nweke, R. N. Nwabueze, C. U. Dike and C. E. NwanyanwuToxicity of phenolic compounds to oxidoreductases of Acinetobacter species isolated from a tropical soil, Department of Microbiology, Federal University of Technology, P. M. B.1526, Owerri, Nigeria. Scientific Research and Essay Vol. 2 (7), pp. 244-250, July 2007).

Other observations during biodegradation in soil and sediment tests with observation of the toxicity lever for microorganisms defined that above the level of c.a 100 mg/L, 2,4 -dinitrophenol may be toxic to the degrader microorganisms (Bartha et al. 1967; Namkoong et al. 1988; Schmidt and Gier 1989).