Automated species and strain identification of bacteria in complexmatrices using FTIR spectroscopy

摘要

Fourier Transform Infrared (FTIR) spectroscopy provides a highly selective and reproducible means for the chemically-based discrimination of intact microbial cells which make the method valuable for large-scale screening of foods. Thegoals of the present study were to assess the effect of chemical interferents, such as food matrices, different sanitizingcompounds and growth media, on the ability of the method to accurately identify and classify L. i. welshimeri,E. coli, S. cholerasuis, S. subterranea, E. sakazakii, and E. aerogenes. Moreover, the potential of FTIR spectroscopy fordiscrimination of L. innocua and L. welshimeri of different genotypes and the effect of growth phase on identificationaccuracy of L. innocua and L. welshimeri were tested. FTIR spectra were collected using two different samplepresentation techniques – transmission and attenuated total reflection (ATR), and then analyzed using multivariatediscriminant analysis based on the first derivative of the FTIR spectra with the unknown spectra assigned to the speciesgroup with the shortest Mahalanobis distance. The results of the study demonstrated 100% correct identification anddifferentiation of all bacterial strains used in this study in the presence of chemical interferents or food matrices, betterthan 99% identification rate in presence of media matrices, and 100% correct detection for specific bacteria in mixedflora species. Additionally, FTIR spectroscopy proved to be 100% accurate when differentiating between genotypes of L.iand L. welshimeri, with the classification accuracy unaffected by the growth stage. These results suggest thatFTIR spectroscopy can be used as a valuable tool for identifying pathogenic bacteria in food and environmental samples