Evaluation of microscopic techniques to observe iron precipitation in a natural microbial biofilm

Abstract Iron biomineralization in a microbial biofilm consortium from Canadian Shield groundwaters has been investigated with different microscopic techniques. The advantages and disadvantages of the different methods of observing a biofilm growing on an opaque mineral surface are discussed. Scanni...

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Bibliographic Details
Published in:FEMS microbiology ecology 1998-08, Vol.26 (4), p.297-310
Main Authors: Brown, D. Ann, Beveridge, Terry J., Keevil, C. William, Sherriff, Barbara L.
Format: Article
Language:English
Subjects:
Animal, plant and microbial ecology
Bacteria
Biofilm
Biofilms
Biological and medical sciences
Canadian Shield
Consortia
Differential interference contrast microscopy
Ecology
Electron microscopy
Fundamental and applied biological sciences. Psychology
Ingestion
Iron
Iron biomineralization
Microbial ecology
Microbiology
Microorganisms
Microscopes
Microscopic technique
Microscopy
Mineralization
Natural environment
Protozoa
Scanning electron microscopy
Sediments
Slime
Transmission electron microscopy
Various environments (extraatmospheric space, air, water)
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Summary:Abstract Iron biomineralization in a microbial biofilm consortium from Canadian Shield groundwaters has been investigated with different microscopic techniques. The advantages and disadvantages of the different methods of observing a biofilm growing on an opaque mineral surface are discussed. Scanning electron microscopy was able to show the initial attachment and dispersion of bacteria on the mineral surfaces, whereas transmission electron microscopy gave greater detail and revealed the precise location of the iron precipitation on cell surfaces, including S-layers, and also throughout the extrapolymeric slime of the biofilm. Episcopic Nomarski differential interference contrast microscopy allowed direct observation of biofilm dynamics and confirmed the precipitation of iron directly onto certain bacteria, which were then specifically ingested by protozoa. This novel ingestion of iron-coated bacteria by protozoans essentially eliminated iron from solution and trapped it within the biofilm. Over time in the natural environment, this iron, enmeshed within a biofilm, may become incorporated into iron-rich sediments.
ISSN:0168-6496
1574-6941
DOI:10.1111/j.1574-6941.1998.tb00514.x