Fourier Transform Infrared microspectroscopy and chemometrics as a tool for the discrimination of cyanobacterial strains

Fourier Transform Infrared (FTIR) microspectroscopy, in combination with ch emometrics, was investigated as a novel method to discriminate between cyan obacterial strains. In total, 810 absorbance spectra were recorded from one eukaryotic and five cyanobacterial taxa spanning three genera and includin g two strains of one species, Microcystis aeruginosa. Principal Component A nalysis (PCA) based classification techniques such as Soft Independent Mode lling of Class Analogy (SIMCA) and K-Nearest Neighbours (KNN) were investig ated. Different spectral regions using derivative spectra were investigated to find the best combinations for classification. The highest rate of corr ect classifications (99-100%) was achieved using first derivative spectra w ith a spectral region of 1800-950 cm(-1) for both the SIMCA and KNN. A dend rogram constructed using averaged spectra of the six taxa studied showed th at the two strains of Microcystis aeruginosa exhibited the highest degree o f similarity, while the eukaryotic taxon was the most dissimilar from the p rokaryotic taxa. (C) 1999 Published by Elsevier Science Ltd. All rights res erved.