Potential Function of Added Minerals as Nucleation Sites and Effect of Humic Substances on Mineral Formation by the Nitrate-Reducing Fe(II)-Oxidizer Acidovorax sp. BoFeN1

摘要

The mobility of toxic metals and the transformation of organic pollutants in the environment are influenced and in many cases even controlled by iron minerals. Therefore knowing the factors influencing iron mineral formation and transformation by Fe(II)-oxidizing and Fe-(III)-reducmg bacteria is. crucial for understanding the fate of contaminants and for the development of remediation technologies. In this study we followed mineral formation by the nitrate-reducing Fe(II)-oxidizmg strain Acidovorax sp. BoFeNi in me presence of the crystalline Fe(III) (oxyhydr)-oxides goethite, magnetite and hematite added as potential nucleation sites. Mossbauer spectroscopy analysis of minerals precipitated by BoFeNl in~( S7) Fe(II)-spiked microbial growth medium showed that goethite was formed in the absence of mineral additions as well as in the presence of goethite or hematite. The presence of magnetite minerals daring Fe(II) oxidation induced the formation of magnetite in addition to goethite, while the addition of humic substances along with magnetite also led to goethite but no magnetite. This study showed that mineral formation not only depends on the aqueous geochemical conditions but can also be affected by the presence of mineral micleatiori sites that initiate precipitation of the same underlying mineral phases.