Effect of Substrate Concentration and Organic and Inorganic Compounds on the Occurrence and Rate of Mineralization and Cometabolism

Abstract

Isopropyl N -phenylcarbamate (IPC) at 400 pg and 1 μg/ml was mineralized in samples of sewage, but only the lower concentration was mineralized in lake water samples in a 50-day period. IPC at 1 μg/ml disappeared from lake water, but it was converted to organic products. Mineralization of IPC at 400 pg/ml in lake water was enhanced by additions of inorganic nutrients or a mixture of nonchlorinated water pollutants but not by yeast extract or mixtures containing aromatic compounds or excretions of primary producers. The mineralization of 200 pg of 2,4-dichlorophenoxyacetate per ml of lake water was not affected by additions of low levels of yeast extract or compounds excreted by primary producers but was enhanced by low concentrations of mixtures of water pollutants. It is suggested that some chemicals that are found to be converted only to organic products, presumably by cometabolism, in tests using the concentrations commonly employed in laboratory evaluations may be mineralized at the lower concentrations prevailing in natural waters.

Effect of inorganic nutrients on the acclimation period preceding mineralization of organic chemicals in lake water

“…The same investigation showed that the acclimation period preceding PNP mineralization in lake water was markedly decreased when a mixture of several inorganic salts was added. The present study shows that the acclimation period for PNP mineralization was shortened by adding P, N, or S. A stimulation of biodegradation of organic chemicals in lake water by added inorganic nutrients, including P, N, Fe, and Mg, has been reported previously (la, [3][4][5]9). It is noteworthy that'the greatest effects noted in the present study were obtained at P concentrations much higher than those typically found in New York lakes, which usually range from 1 to 70 ,ug of P per liter (1).…”

Effects of chemical structure and exposure on the microbial degradation of polycyclic aromatic hydrocarbons in freshwater and estuarine ecosystems

“…However, the present study provides data from the use of sediment: water microcosms for a comparative study of the effects of past chemical exposure and adaptation of sediment microbial populations on the mineralization rates of six PAHs in both estuarine and freshwater ecosystems. Since the degradation rate of PAHs may be affected by temperature [17,20] and exposure concentration [17,18], in this study these variables were held constant (22°C and 500 ng/g) to facilitate the comparison of PAH mineralization rates among ecosystems and different PAHs.…”

Kinetic Concepts for Measuring Microbial Rate Constants: Effects of Nutrients on Rate Constants

“…In a related study, Rubin et al (14) found the extent of mineralization of phenylacetate and p-nitrophenol to be greater in a eutrophic lake than in a mesotrophic lake. The effects of inorganic nutrients have been examined by workers in several laboratories (3,4,7,19). Dibble and Bartha (3) reported that mineral nutrient ratios of 60:1 (C/N) and 800:1 (C/P) resulted in the greatest amount of degradation of oil sludge on soil.…”