Affiliations: Department of Medical Physics, Anna University, Chennai, India | Department of Medical Physics, Red Sea University, Port Sudan, Sudan | Centre for Advanced Studies in Botany, University of Madras, Chennai, India
Note:  Corresponding author: Singaravelu Ganesan, Professor, Department of Medical Physics, Anna University, Chennai-600 025, India. Tel.: +91 44 22358720; Fax: +91 44 22358685; E-mail: [email protected]
Abstract: This study focuses on identification and classification of Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi and Klebsiella pneumoniae based on steady-state and fluorescence lifetime spectroscopy. Bacterial samples were cultured under controlled conditions and diluted in saline to 4×106 cell/ml for analysis. Two excitations at 250 nm (aromatic amino acids and nucleic acids, AAA+NA) and 280 nm (tryptophan) were used for steady-state while fluorescence lifetime decays were acquired at 280 nm excitation. A small range of difference was obtained for tryptophan lifetime from the four bacteria for the fast lifetime component (1.61–1.73 ns) and the slow lifetime component (5.25–5.44 ns). The application of principal component analysis (PCA) to steady-state fluorescence spectra resulted in the successful classification of the four bacteria and highest percentage of good classification was obtained for tryptophan (λexc=280 nm). Our results demonstrated that steady-state fluorescence spectroscopy coupled to PCA is a powerful tool for identification and classification of bacterial pathogens at genus level.
Keywords: Fluorescence spectroscopy, bacterial pathogens, identification, principal component analysis