Sing Teng Chua
University of Copenhagen
(host: A. Allard)
Spatial Organisation and Light–Matter Coupling in Immobilised Photosynthetic Systems
Immobilised cultivation strategies such as biofilms and hydrogel encapsulation are increasingly explored for light-driven algal biotechnology. In these systems, spatial confinement reorganises cellular behaviour, light propagation, and resource transport across multiple length scales. At the single-colony level, Chlamydomonas reinhardtii microcolonies were used to examine how confinement reshapes growth dynamics. Time-lapse microscopy and single-cell tracking revealed pronounced intra-colony heterogeneity, including radially propagating oscillations in parent cell size and chlorophyll autofluorescence. These patterns indicate coordinated cell-cycle regulation emerging from contact inhibition and nutrient micro-gradients under restricted mass transfer [1]. At the population scale, algal aggregates embedded within hydrogels displayed depth-dependent size distributions relative to the gel–air interface. Scalar irradiance measurements coupled with Monte Carlo light propagation modelling showed that heterogeneous aggregate distributions substantially reshaped internal light fields compared with uniform biofilms. Matrix engineering, including the incorporation of scattering elements, enabled modulation of the optical microenvironment to enhance volumetric light harvesting [2]. These principles could be further applied through 3D bioprinting to construct spatially defined microbial consortia such as layered cocultures of cyanobacteria with complementary chlorophyll compositions to broaden spectral utilisation. Furthermore, immobilised photosynthetic systems could be extended to functional biomaterial fabrication, where Komagataeibacter hansenii and C. reinhardtii co-culture enabled bulk bacterial cellulose formation with tunable geometry beyond the air–liquid interface [3]. These studies reveal how structural complexity and dynamic heterogeneity in confined cellular communities give rise to emergent functions, providing a foundation for rational design of efficient and programmable photosynthetic systems.
References:
[1] S.T. Chua, J. Kotar, M. Kühl, A.G. Smith, S. Vignolini, & P. Cicuta. Uncoupling growth and division in Chlamydomonas reinhardtii colonies: consistent cell cycle regulation under confinement. ISME Communications 5(1), ycaf104, https://doi.org/10.1093/ismeco/ycaf104 (2025).
[2] S.T. Chua, A. Smith, S. Murthy, M. Murace, H. Yang, L. Schertel, M. Kühl, P. Cicuta, A.G. Smith, D. Wangpraseurt, & S. Vignolini. Light management by algal aggregates in living photosynthetic hydrogels. Proc. Natl. Acad. Sci. U.S.A. 121(23) e2316206121, https://doi.org/10.1073/pnas.2316206121 (2024).
[3] K. Yu, S.T. Chua, R. Zhao, A. Smith, M. Kühl, A.G. Smith, T. Ellis, & S. Vignolini. Artificial Symbiosis for Bulk Production of Bacterial Cellulose Composites. Advanced Materials e14125. https://doi.org/10.1002/adma.202514125 (2026).
