The strategy for correcting interference from water in Fourier transform infrared spectrum based bacterial typing

Accurate and effective identification and typing of microorganisms is important in epidemiological surveillance. Fourier transform infrared (FTIR) spectroscopy is a promising bacterial typing method based on extracting the infrared spectrum signal-related biochemical features of intact microbiological cells. Unfortunately, the FTIR signals of bacteria are disturbed by many factors, especially the unavoidable absorbance of H₂O, and many studies have focused only on the internal biochemical information. In this study, the interference from water was analyzed and verified by experimental data. The infrared absorbance of H₂O overlapped with the protein (1200-1800 cm^-1) and lipid regions (2800-3700 cm^-1), but had little impact on the polysaccharide and nucleic acid region (900-1200 cm^-1). The elimination of the protein and lipid region markedly decreased the interference of H₂O and increased the typing accuracy. The results indicate that the polysaccharide and nucleic acid region (900-1200 cm^-1) is the only credible region for bacterial typing, and typing based on this region not only reduces the size of the data analysis, but results in more reliable typing results.