Fourier Transform Infrared Spectroscopy and Multivariate Analysis

Abstract

This study examined the potential of Fourier transform infrared (FT-IR) absorbance spectroscopy to detect biochemical changes in bacterial cells that occur during bacterial growth phases in batch culture. Two bacterial strains, Escherichia coli ATCC 25922 and Listeria innocua ATCC 51742 were cultured in brain heart infusion (BHI) broth and incubated at 37C and cells recovered at: the lag phase (3 h), the log phase (7 h), the stationary phase (24 h), and the death phase (10 days) from incubation in BHI (n = 2). Major variations in the biochemical structure of bacterial cells during growth were observed. Over the range of 1800–900 cm-1, loadings 1 (principal component [PC] 1) and 2 (PC2) accounted for 88% of the total variability (76% and 12%, respectively) for E. coli cells, and 80% (72% and 8%, respectively) for L. innocua cells. Changes were attributable to cellular structure of bacterial cells (the variation in nucleic acids, proteins, lipids and polysaccharides) that occur during the growth phases.