Quieting a noisy antenna reproduces photosynthetic light harvesting spectra

TL;DR

This paper introduces a noise-canceling network model that explains how photosynthetic organisms optimize their light absorption spectra to maximize efficiency under noisy environmental conditions.

Contribution

It presents a novel theoretical framework linking physiological noise, efficiency, and absorption spectra, explaining wavelength adaptations across different photosynthetic organisms.

Findings

Optimal absorption spectra depend on environmental light conditions.

Light harvesting antennae are tuned to minimize excitation noise.

The model unifies observed wavelength dependence in various organisms.

Abstract

Photosynthesis is remarkable, achieving near unity light harvesting quantum efficiency in spite of dynamic light conditions and noisy physiological environment. Under these adverse conditions, it remains unknown whether there exists a fundamental organizing principle that gives rise to robust photosynthetic light harvesting. Here, we present a noise-canceling network model that relates noisy physiological conditions, power conversion efficiency, and the resulting absorption spectrum of photosynthetic organisms. Taking external light conditions in three distinct niches - full solar exposure, light filtered by oxygenic phototrophs, and under sea water - we derive optimal absorption characteristics for efficient solar power conversion. We show how light harvesting antennae can be finely tuned to maximize power conversion efficiency by minimizing excitation noise, thus providing a unified theoretical basis for the experimentally observed wavelength dependence of light absorption in green plants, purple bacteria, and green sulfur bacteria.