Summary
(1) The results of experiments on the continuous perfusion of aerated solutions of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D), 2, Methyl-4, chlorophenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) through garden soil indicate that the kinetics of their breakdown are essentially similar.
(2) Three phases can be distinguised: (a) an immediate initial adsorption onto soil colloids amounting to 0.167±0.035 mg per g dry soil, (b) a lag phase of varying duration in which there is little or no disappearance of herbicide, (c) a final phase of rapid complete detoxication. Such “enriched” soils detoxicate subsequent perfusions with the same herbicide molecule at a constant high rate. Enrichment times for 2,4-D, MCPA and 2,4,5-T are roughly of the order or 14, 70 and 270 days respectively.
(3) This indirect evidence, from kinetics of detoxication, of the development of a bacterial flora adapted to herbicide breakdown, is strongly supported by experiments in which the detoxicating activity of such enriched soils was completely destroyed by low concentrations (0.01%) of the bacterial poison, sodium azide.
(4) Attempts to isolate in pure culture the 2,4-D-decomposing organism were successful. Preliminary classification work relegates the organism to the “Bacterium globiforme group”. Further confirmatory work is required.
(5) Cross perfusion experiments in which 2,4-D enriched soils were perfused with MCPA and vice versa indicate that both can detoxicate the other analogue, although at a somewhat lower rate than the soil directly enriched with that analogue.
(6) 2,4-D enriched soil will not detoxicate 2,4,5-T although some activity may be temporarily induced by an intermediate perfusion with MCPA.
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References
Audus, L. J., A new soil perfusion apparatus. Nature (London),158, 419 (1946).
Audus, L. J., The biological detoxication of 2,4-dichlorophenoxyacetic acid in soil. Plant and Soil2, 31–35 (1949).
Audus, L. J., Biological detoxication of 2,4-dichlorophenoxyacetic acid in soils: Isolation of an effective organism. Nature (London)166, 356 (1950).
Audus, L. J., and Quastel, J. H., Coumarin as a selective phytocidal agent. Nature (London)159, 320–324 (1947).
Bandurski, R. S., Spectrophotometric method for the determination of 2,4-D. Botan. Gaz.108, 446–449 (1947).
Conn, H. J., A type of bacterium abundant in productive soils but apparently lacking in certain soils of low productivity. Tech. Bul. 138, N.Y. Agric. Exp. Station (1928).
Conn, H. J., and Darrow, N. A., Influence of various non-nitrogenous compounds on the growth of certain bacteria in soils of low productivity. Tech. Bull. 172, N.Y. Agric. Exp. Station (December 1930).
Forbes-Jones, R., and Baker, H. G., The effect of some purines and related compounds on the seedling growth ofAvena sativa L. Ann. Botany N.S.7, 379–390 (1943).
Freed, V. H., Qualitative reaction for 2,4-dichlorophenoxyacetic acid. Science107, 98–99 (1948).
Happold, F. C., The oxidation of aromatic rings by micro-organisms in metabolism. Biochemical Society Symposia, No. 5, p. 85–96, Cambridge (1950).
Hoagland, D. R., and Snyder, W. C., Nutrition of the strawberry plant under controlled conditions. Proc. Am. Soc. Hort. Sci.30, 288–294 (1933).
Kandler, O., Untersuchungen über den Zusammenhang zwischen Atmungsstoffwechsel und Wachstumsvorgängen in vitro kultivierten Maiswurzeln. Z. Naturforsch.56, 203–211 (1950).
Lees, H., and Quastel, J. H., Biochemistry of nitrification in soils. I. Kinetics of, and the effects of poisons on, soil nitrification as studied by a soil perfusion technique. Biochem. J.40, 803–828 (1946).
Lochhead, A. G. and Taylor, C. B., Qualitative studies in soil micro-organisms. Can. J. Research C.16, 152–173 (1938).
Mann, P. J. G. and Quastel, J. H., Manganese metabolism in soils. Nature (London)158, 154 (1946).
Newman, A. S. and Thomas, J. R., Decomposition of 2,4-dichlorophenoxyacetic acid in soil and liquid media. Proc. Soil Sci. Soc. Am.14, 160–164 (1950).
Nutman, P. S., Thornton, H. G. and Quastel, J. H., Plant growth substances as selective weedkillers. Inhibition of plant growth by 2,4-dichlorophenoxyacetic acid and other plant growth substances. Nature (London)155, 497 (1945).
Stanier, R. T., Problems of bacterial oxidative metabolism. Bacteriological Reviews14 179–191 (1950).
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Audus, L.J. The biological detoxication of hormone herbicides in soil. Plant Soil 3, 170–192 (1951). https://doi.org/10.1007/BF01676373
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DOI: https://doi.org/10.1007/BF01676373