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The Role of Dissolved Silica on the Biodegradation of Octylamine

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journal contribution
posted on 14.09.1999, 00:00 by Hildegarde Selig, Kim F. Hayes, Peter Adriaens
Dissolution of aquifer-associated mineral solids such as silica may affect the natural bioattenuation of organic compounds by altering their chemical speciation and thus their biodegradability. A study was conducted to evaluate the effect of dissolved silica on the rates of biodegradation of a cationic surfactant, octylamine, by Rhodococcus erythropolis. The presence of dissolved silica or a surrogate added by dissolving sodium metasilicate significantly enhanced the biodegradation rates of octylamine. Microbial kinetic studies based on the Monod/Haldane equation indicated that the rate enhancement was caused by a decrease in the inhibitory properties of octylamine, rather than by an improvement in buffering of the medium. In the presence of dissolved silica, μmax and Ks remain virtually unaffected, but the inhibition constant, Ki, increased several orders of magnitude (from Ki = 1.32 mM in the silica-free system to Ki > 106 mM in the silica system). Surface tension studies suggested that the presence of dissolved silica significantly decreased the surface-activity of octylamine.