Micro‐ and nano‐scale mineralogical characterization of Fe(II)‐oxidizing bacterial stalks

Neutrophilic, microaerobic Fe(II)‐oxidizing bacteria (FeOB) from marine and freshwater environments are known to generate twisted ribbon‐like organo‐mineral stalks. These structures, which are extracellularly precipitated, are susceptible to chemical influences in the environment once synthesized. In this paper, we characterize the minerals associated with freshwater FeOB stalks in order to evaluate key organo‐mineral mechanisms involved in biomineral formation. Micro‐Raman spectroscopy and Field Emission Scanning Electron Microscopy revealed that FeOB isolated from drinking water wells in Sweden produced stalks with ferrihydrite, lepidocrocite and goethite as main mineral components. Based on our observations made by micro‐Raman Spectroscopy, field emission scanning electron microscopy and scanning transmission electron microscope combined with electron energy‐loss spectroscopy, we propose a model that describes the crystal‐growth mechanism, the Fe‐oxidation state, and the mineralogical state of the stalks, as well as the biogenic contribution to these features. Our study suggests that the main crystal‐growth mechanism in stalks includes nanoparticle aggregation and dissolution/re‐precipitation reactions, which are dominant near the organic exopolymeric material produced by the microorganism and in the peripheral region of the stalk, respectively.     

Supplementation with an Inorganic Iron Source Modulates the Metalloproteomic Profile of the Royal Jelly Produced by Apis mellifera L.

Biological Trace Element Research - This study aimed to evaluate the quality of the royal jelly produced by Apis mellifera bees in the presence of different iron concentrations (ferrous sulfate...     

Total Mercury Determination in Muscle and Liver Tissue Samples from Brazilian Amazon Fish Using Slurry Sampling

Biological Trace Element Research - This paper presents a slurry sampling method for total mercury determination by graphite furnace atomic absorption spectrometry (GFAAS) in tissue of fish from...