Effects of toxic organotin compounds on bacteria investigated by micro-raman spectroscopy.
Résumé
Within the framework of the detection of toxic substances using
specific bacteria, the effect of the toxic chemical compound tributyltin chloride
(TBT) on the bacterium Escherichia coli TBT3 was investigated using a noninva-
sive approach based on micro-Raman spectroscopy. Various cellular densities
with OD Q1ranging from 1 to 4 and harvested at different growth phases were
induced for 1 h with different TBT concentrations: 1, 3, 5, and 10 mM. As an
original contribution, the Raman results show that, in these conditions, the
vibrational signatures of bacteria were affected by the presence of the toxic
TBT compound, mainly in the signal characteristics from carbohydrates and
lipids. Hierarchical cluster analysis (HCA) carried out on the Raman data in
these regions makes it possible to classify the spectra in three groups according
to the TBT concentration, confirming the progressive influence of the chemical
pollutant on the bacterium. This work shows the potentiality for the Raman
technique on this subject, even though a low detection threshold corresponding
with a concentration of 1 mM of TBT was established.