Adaptation of Green Photosynthetic Bacteria to Different Illumination According to Spectroscopy Data on Chlorosomes

The absorption and circular dichroism spectra of the chlorosomes isolated from green photosynthetic Chloroflexus aurantiacus bacteria grown under different illumination were studied. It was found that the spectra shift to a red side and become narrower and larger in amplitude as this illumination decreases. A theoretical modeling of data obtained was carried out using a theory of excitons. It was concluded that the number of bacteriochlorophyll c molecules in the linear chains (that form a basis of the elementary blocks of chlorosomes) increases as the intensity of light, under which bacteria are grown, decreases. It was suggested that this phenomenon increases the efficiency of capturing weak light fluxes and, thus, increases the chances of bacterial survival in conditions of sunlight deficiency.