Heavy metals, currently present in the environment beyond permissible limits, are extremely hazardous elements which have been recognized as having influence on fungal physiology. Exposure to heavy metals results in changes in physiological processes, but also in the chemical composition and content of macromolecules (nucleic acids, proteins, lipids and polysaccharides, etc.) of fungal cells. Fourier-transform infrared spectroscopy (FTIR) is a powerful technique for the study of those changes because of the simplicity of sample preparation and avoidance of any chemicals (lower cost and lesser environmental impact), reliability and short measurement times, compared to other available methods. The present study was designed to characterize the chemical changes in Metarhizium robertsii spores as a result of exposure to cadmium, cobalt, lead and tin. The spores were analysed by the use of FTIR spectroscopy after cultivation of the fungus in presence of metal ions at concentrations: 0.998 mg dm-3, 9.982 mg dm-3, 49.910 mg dm-3, 99.821 mg dm-3 (corresponding to 1, 10, 50 and 100 ppm, respectively). The results revealed that heavy metals influenced the chemical composition (proteins, lipids, polysaccharides, nucleic acids) of M. robertsii spores, and depending on their concentration in the medium affected all chemical groups present in fungal cells. Hydroxyl, carbonyl, methyl, ester, amino and phosphoryl functionalities played a significant role in the response of the fungus to the presence of metals in the medium. These results indicate that FTIR is a useful technique to determine the chemical changes in fungi exposed to heavy metals.

25.2.2020