Fluorescence of chlorosomal bacteriochlorophylls in organic solvents

Chlorosomal bacteriochlorophylls are the main photosynthetic pigments of green sulfur bacteria, that are anoxygenic phototrophic microorganisms. The spectral properties of chlorophylls of vascular plants, algae and cyanobacteria are well studied, however, the spectral-luminescent properties of their related compounds, bacteriochlorophylls, which participate in anoxygenic photosynthesis, are practically not described in the scientific literature. The polarity of the solvent and the environment have a significant effect on the emission spectra (bacterio)chlorophylls, which is expressed in the spectral shift of the absorption and fluorescence maxima, as well as changes in the fluorescence intensity. The spectral characteristics of bacteriochlorophylls d and e were obtained in organic solvents such as acetone, methanol, ethanol and isopropanol, as well as in acetone-ethanol (7 : 2) and acetone-methanol (7 : 2) mixtures. These solvents are most often used for the extraction of bacteriochlorophylls from bacterial cells, so the work will be useful for the development of methods for the quantitative determination of chlorosomal bacteriochlorophylls in bacterial cells or in samples of natural water.