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Abstract
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 noninvasive approach based on micro‐Raman spectroscopy. Various cellular densities with optical density (OD) ranging from 1 to 4 and harvested at different growth phases were induced for 1 h with different TBT concentrations: 1, 3, 5, and 10 µM. 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 µM of TBT was established.
Acknowledgments
This research was supported by the CER 2000–2006 grant, research program no. 18035 (Ville de la Roche sur Yon, Conseil Général de Vendée, Conseil Régional des Pays de la Loire, Ministère Français chargé de la Recherche). We are indebted to all colleagues of the Laboratoire d'Applications des Lipases (LALUM) for all suggestions, especially for advice in biology. The authors are grateful to Prof. Alison Bates, English native and English teacher at Université du Maine (Le Mans, France), for her help in language proof reading and improvement.