Microbial Photonics Across Scales

Phototrophic microorganisms including diverse bacteria harness sunlight to execute metabolic functions, rendering them indispensable as the base of most of the aquatic food webs. Harnessing light efficiently, a key prerequisite for survival and fitness of such species, is achieved biochemically via photoreceptors and light-sensitive actuators, cascading into gene expressions, protein functions, and tactic traits. Our recent findings on bacterial sulphur globules—energy-rich intracellular organelles in sulphur metabolising bacteria—reveal optical properties which could allow active manipulation of light fields within individual cells. Building on this fundamental discovery, MicroPAS proposes a paradigm-shifting approach to organelle-mediated light manipulation, grounded in the physics of light-matter interactions. Using a combination of microscopic and spectroscopic techniques on both lab-grown and nature-isolated sulphur bacterial species, together with data-backed numerical modelling, MicroPAS will uncover how species-specific intracellular organelles (e.g., sulphur or calcite globules), and their internal distribution determine optical modes, enabling active light-guidance. By accounting for the evolving cell shape, globule attributes and bio-energetics over the course of their growth stages, the results, across individual to collective scales, will delineate if and how the wavelength, intensity and photon retention times are actively regulated by bacteria. Finally, I will analyse emergent phenomena at collective scales where self-regulation of light may result in enhanced penetration or scattering, ultimately allowing to leverage feedback and nonlinear effects for designing living photonic circuits. By uncovering how intracellular light modulation governs optimal behaviour and physiology, MicroPAS will pioneer an unprecedented data-rich biophotonic framework, and thereby advance next generation of living optical matter based on nature-inspired light modulation.