Preliminary results of using ESR to examine biofilms

Abstract

This preliminary work shows ESR (Electron SpinResonance) can be used to detect biofilms, particularly from Fe-metabolising bacteria. A film was detected by ESR as early as 1 day, hence possibly more sensitively than by fluorescent methods. Films can probably be detected as early as one hour. Spectra contain a very broad peak at g=2.13, probably due to ferrihydrite. Results of field experiments from streams and ponds in New Zealand and Japan, particularly the Minoh River, showed a general increase of ferrihydrite with time. Loss by exfoliation was later than 20 days. The rate of accumulation was faster in a nutrient-rich stagnant pond. Hematite (g=4.3) was often observed, magnetite (g=9) once, and usually small amounts of a common bacterial decay product. The latter was detected for at least 18 months film storage. ESR is a particularly good tool for observing the growth of oxic biofilms containing *Corresponding author Fe-metabolising bacteria, and should be just as sensitive for observing Mn-metabolising bacteria in reducing conditions.

A Ferromagnetic Resonance Study of Iron Complexes as Biologically Synthesized in Magnetic Bacteria

“…Thus far, EPR studies on the biogenic magnetic compounds have been limited in number. [19][20][21][22] Whitehead et al have reported that the biofilms from a river side showed an EPR signal originating from Fe-metabolizing bacteria. They identified the EPR spectra of ferrihydrite, hematite and magnetite.…”

“…They identified the EPR spectra of ferrihydrite, hematite and magnetite. 19) FMR (Ferromagnetic resonance) studies have also identified biogenic magnetite and ferrihydrite. [20][21][22] However, these studies were concerned only with the FMR of magnetite and ferrihydrite fractions, but not those of other cell fractions.…”