FOURIER TRANSFORM INFRARED SPECTROSCOPY OF MICROALGAE AS A NOVEL TOOL FOR BIODIVERSITY STUDIES, SPECIES IDENTIFICATION, AND THE ASSESSMENT OF WATER QUALITY¹

Abstract

Fourier transform infrared (FTIR) spectrometry was used to study the spectral features of 12 eukaryotic and two prokaryotic species of microalgae. The algae were cultured in liquid media containing either NO 3 ) or NH 4 + as the sole N-source; for the NH 4 + treatment, the algae were subjected to shortterm (24 h) or long-term (1 month) incubations; for the hypersaline species, cells were also grown in the presence of 2 M NaCl. Over 500 spectra, acquired from at least three distinct cultures for each species, in each growth regime, were subjected to hierarchical cluster analysis (HCA) and were successfully separated according to their taxonomy, showing that the overall spectra were characteristic of each species and that this technique could be fruitfully employed to separate microalgal species living in a similar condition (as would be the case for a natural assemblage). In addition, in most cases, it was possible to differentiate between algae subjected to different growth treatments although belonging to the same species. We also demonstrated that it is possible to accurately identify species and determine the nutritional status of their environment of origin (e.g., N-source), provided that suitable FTIR spectral libraries are available. This study aims to provide the basis for the development of rapid, easy, and inexpensive methods for the evaluation of biodiversity in natural phytoplankton samples and to monitor the water quality of natural environments.

Carbon and nitrogen fluxes in the marine coccolithophore Emiliania huxleyi grown under different nitrate concentrations

“…Aliquotes of 50 μL of these suspensions were deposited on silica windows (Crystran Ltd., Poole, UK) and desiccated in an oven at 60°C for at least 3 hours. Silica windows on which 50 μL of ammonium formate solution were deposited were treated as the samples and used as blanks (Domenighini and Giordano, 2009). FTIR spectra were acquired with a Tensor 27 FTIR spectrometer (Bruker Optics, Ettlingen, Germany) as described in Domenighini and Giordano (2009).…”

“…Silica windows on which 50 μL of ammonium formate solution were deposited were treated as the samples and used as blanks (Domenighini and Giordano, 2009). FTIR spectra were acquired with a Tensor 27 FTIR spectrometer (Bruker Optics, Ettlingen, Germany) as described in Domenighini and Giordano (2009). All spectra were baseline corrected prior to any analysis by the application of the Rubberband correction function of the OPUS 6.5 software (Bruker Optics, Ettlingen, Germany); they were then normalized to the amide I band (∼ 1650 cm -1 ).…”

Evaluation of Dicentrarchus labrax Meats and the Vegetable Quality of Beta vulgaris var. cicla Farmed in Freshwater and Saltwater Aquaponic Systems

“…Bands were attributed to cellular pools according to Giordano et al [16]. Relative ratios of carbohydrates, lipids and proteins were calculated as described by Domenighini and Giordano [17] and Palmucci et al [18].…”

Snapshot prediction of carbon productivity, carbon and protein content in a Southern Ocean diatom using FTIR spectroscopy

“…The use of spectroscopic techniques such as Raman and Fourier transform infrared (FTIR) spectroscopy in phytoplankton studies has been widely explored (Heraud et al, 2007b;Heraud et al, 2008;Domenighini and Giordano, 2009;Dean et al, 2012Dean et al, , 2010. These techniques involve irradiating a sample with specific wavelengths of light and measuring light scattering (Raman spectroscopy) or absorbance (FTIR spectroscopy) by the sample.…”