Identification of oral bacteria by Raman microspectroscopy

Four different species of bacteria (streptococcus mutans, s. sanguis, s. intermedius and s. oralis) important in the field of oral biology were studied using spontaneous Raman scattering spectroscopy. Spectra of several bacterial colonies of each type were acquired using a Raman microscope system. After correction for system background and fluorescence, the Raman spectra were grouped using a blind clustering algorithm. The clusters thus generated were found to correspond closely to the four species of bacteria, with 5 misclassifications out of 80 samples. The clustering may be due to differences in the concentrations of amino acids and nucleic bases in the various bacterial species. The results suggest that Raman spectroscopy may be used as a rapid means of identifying the species of bacterial colonies of oral streptococci.