In situ detection and identification of microorganisms at single-colony resolution by spectral imaging

The in situ detection and identification of environmental microorganisms is important for general microbial ecology research. In addition, the rapid detection of microbial contamination in food-processing plants is essential. The current paper proposes a method for the rapid detection and identification of microorganisms using spectral imaging. Photosynthetic and non-photosynthetic bacterial colonies with different absorption spectra in the near-infrared wavelength region were measured directly from a Petri dish. The bacterial colonies were distinguished and subsequently typed using multiple discriminant analysis. The accuracy of the detection and identification of colonies of various sizes was evaluated. The results showed that colonies with diameters of 100 and 300 μm could be detected and identified, respectively, with adequate accuracy. Moreover, using our novel application of this spectral-imaging technique, the bacterial detection and identification times were reduced by more than half and by a few weeks, respectively, compared with conventional methods.