Discrimination of cyanobacterial strains isolated from saline soils in Nakhon Ratchasirna, Thailand using attenuated total reflectance FTIR spectroscopy

A method was developed whereby high quality FTIR spectra could be rapidly acquired from soil-borne filamentous cyanobacteria using ATR FTIR spectroscopy. Spectra of all strains displayed bands typical of those previously reported for microalgae and water-borne cyanobacteria, with each strain having a unique spectral profile. Most variation between strains occurred in the C-O stretching and the amide regions. Soft Independent Modelling by Class Analogy (SIMCA) was used to classify the strains with an accuracy of better than 93%, with best classification results using the spectral region from 1800-950 cm(-1). Despite this spectral region undergoing substantial changes, particularly in amide and C-O stretching bands, as cultures progressed through the early-, mid- to late-exponential growth phases, classification accuracy was still good (similar to 80%) with data from all growth phases combined. These results indicate that ATR/FTIR spectroscopy combined with chemometric classification methods constitute a rapid, reproducible, [GRAPHICS] and potentially automated approach to classifying soilborne filamentous cyanobacteria.