Gary Wedemeyer 1966 <p><span>Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “non-metabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by&nbsp;</span><i>p</i><span>H, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at&nbsp;</span><i>p</i><span>H values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carrier-mediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranyl ion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.</span></p> application/pdf 10.1128/am.14.4.486-491.1966 en American Society for Microbiology Uptake of 2,4-dichlorophenoxyacetic acid by Pseudomonas fluorescens article