Espectroscopia de fluorescência e de infravermelho por transformada de fourier na rápida diferenciação de cepas de Alkalihalobacillus clausii e Bacillus thuringiensis.

Abstract

The search for faster, more economical, and specialized methodologies for microbiological identification has led researchers to explore spectroscopy as a potential method. This study aimed to find an alternative methodology for analyzing the identification of organic compounds in the analyzed species using fluorescence spectroscopy and Fourier-Transform Infrared (FTIR) spectroscopy. The analyses started from a defined dilution through the Cell Density Meter and the Mac Farland Scale. The results obtained in the fluorescence spectroscopy in the spectral region analyzed may show overlapping modulations related to various compounds such as tryptophan, as well as compounds that are part of the sporulation process since it can contain rods in its vegetative and/or sporulated phase in the analyzed samples. The results of the infrared spectroscopy allowed to conclude the presence of amino acids, proteins, and peptides in the FT-IR spectra in the range of 1540 to 1660 cm-1. These results highlighted the similarity of the organic composition of functional groups (Amides I and II) among the studied species. In the generated 3D maps, it is possible to observe a fluorescence intensity in the region of 300 - 400 nm in the MEE spectra, and it is also observed that in the analysis of Alkalihalobacillus clausii, this intensity is higher when compared to the analysis map of Bacillus thuringiensis. The present study allowed us to conclude that there is a higher concentration of the investigated compound (tryptophan) in the results of the A. clausii analysis compared to the B. thuringiensis analysis through the MEE spectra. Thus, the presence of tryptophan is evidenced with a difference between the species (concentration of the compound), allowing the use of the technique for the characterization of tryptophan in the rapid identification of Bacillus.