Open AccessEvaluation of microscopic techniques to observe iron precipitation in a natural microbial biofilm
Author(s) -
Brown D. Ann,
Beveridge Terry J,
Keevil C.William,
Sherriff Barbara L
Publication year - 1998
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.1998.tb00514.x
Subject(s) - biofilm , biomineralization , precipitation , biology , bacteria , transmission electron microscopy , iron oxide , iron bacteria , microscopy , mineralogy , chemical engineering , materials science , chemistry , nanotechnology , astrobiology , genetics , physics , optics , meteorology , engineering
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.