Chromatic acclimation and population dynamics of green sulfur bacteria grown with spectrally tailored light

TL;DR

This study investigates how green sulfur bacteria adapt their light-harvesting structures to different spectral environments, revealing mechanisms of acclimation and survival under suboptimal light conditions.

Contribution

It uncovers the acclimation strategies of green sulfur bacteria, including pigment regulation and chlorosome size adjustment, in response to spectrally tailored light environments.

Findings

Bacteria regulate pigment levels and chlorosome size in response to light spectrum changes.

Green sulfur bacteria can survive in near-infrared light by capturing low-frequency photons.

Adaptation mechanisms may explain survival near hydrothermal vents.

Abstract

Living organisms have to adjust to their surrounding in order to survive in stressful conditions. We study this mechanism in one of most primitive creatures - photosynthetic green sulfur bacteria. These bacteria absorb photons very efficiently using the chlorosome antenna complexes and perform photosynthesis in extreme low-light environments. How the chlorosomes in green sulfur bacteria are acclimated to the stressful light conditions, for instance, if the spectrum of light is not optimal for absorption, is unknown. Studying Chlorobaculum tepidum cultures with far-red to near-infrared light-emitting diodes, we found that these bacteria react to changes in energy flow by regulating the amount of light-absorbing pigments and the size of the chlorosomes. Surprisingly, our results indicate that the bacteria can survive in near-infrared lights capturing low-frequency photons by the intermediate units of the light-harvesting complex. The latter strategy may be used by the species recently found near hydrothermal vents in the Pacific Ocean.