Membrane Targeted Azobenzene Drives Optical Modulation of Bacterial Membrane Potential

The possibility to control living matter with exogenous stimuli can have tremendous impact on synthetic biology, medicine and materials science, among others. For instance achieving control over cells behaviour remains a challenge at the interface between living and non-living matter,[1] and would enable the development of new bio-mimetic and bio-enabled materials able to perform tasks.[2] Within this context, bacteria have arisen as “active and actively-controllable materials”, exhibiting neuro-like behaviour, extended bioelectric signalling[3,4] and tunable assembly properties.[5] In the last decade, it has been observed that the regulatory element of such an active behaviour is the electrical potential across the membrane, which governs bacteria electrophysiology, metabolisms and bioenergetics.[6] Light can be a powerful tool in these regards, as one can control the membrane potential and, thus, cell function and behaviour remotely and with relatively high spatiotemporal precision.<br/>Here, I will show that a membrane-targeted azobenzene can be used to photo-modulate precisely the membrane potential in cells of the Gram-positive bacterium Bacillus subtilis. We found that upon exposure to blue- green light, the isomerization reaction in the bacteria membrane induces hyperpolarisation of the potential (ΔV = 20 mV), within a bio-mimetic mechanism reproducing the initial fate of retinal. Apart from being promising results in the view to photocontrol bacterial motion and assembly behavior in consortia, this approach also highlights the role of previously uncharacterized ion channels in bacteria electrophysiology.[7]<br/><br/>References<br/>[1] C. Xu, N. Martin, M. Li, S. Mann, Nature 2022, 609, 1029.<br/>[2] F. Zhang, Z. Li, Y. Duan, A. Abbas, R. Mundaca-Uribe, L. Yin, H. Luan, W. Gao, R. H. Fang, L. Zhang, J. Wang, Sci. Robot. 2022, 7, 1.<br/>[3] J. M. Kralj, D. R. Hochbaum, A. D. Douglass, A. E. Cohen, Science (80-. ). 2011, 333, 345.<br/>[4] A. Prindle, J. Liu, M. Asally, S. Ly, J. Garcia-Ojalvo, G. M. Süel, Nature 2015, 527, 59.<br/>[5] V. E. Johansen, L. Catón, R. Hamidjaja, E. Oosterink, B. D. Wilts, T. S. Rasmussen, M. M. Sherlock, C. J. Ingham, S. Vignolini, Proc. Natl. Acad. Sci. U. S. A. 2018, 115, 2652.<br/>[6] J. M. Benarroch, M. Asally, Trends Microbiol. 2020, 28, 304.<br/>[7] T. C. de Souza-guerreiro, G. Bondelli, I. Grobas, S. Donini, V. Sesti, C. Bertarelli, G. Lanzani, M. Asally, G. M. Paternò, Adv. Sci. 2023, 2205007