Abstract
Textile dyeing using microorganisms is a step towards sustainable manufacturing. Computational design offers the prospect of new biosynthetic colourants with better dyeing performance, greater photostability, reduced toxicity, and desired colour. We present a workflow (DyeDactic) to predict halochromism, i.e. colour at different pH values. We filter compound libraries using a graph neural network model to estimate the relevant electronic transition energies of potential colourants. The absorption spectra in the visible region and the colours of the resultant molecules are calculated using time-dependent density functional theory. The populations of protonated and deprotonated species are estimated at different pH values. A weighted sum of their computed absorption spectra gives the predicted colour. The DyeDactic workflow is applied to four natural colourants: emodin, quinalizarin, biliverdin, and orcein, followed by experimental validation. As an illustration we also investigated the molecular mechanism of a red to blue colour change when microbial culture containing polyketide bikaverin is autoclaved. The workflow represents a useful tool to guide chemoenzymatic modifications to achieve industrial applicability.
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Data availability
The results from TD-DFT calculations and the trained chemprop models are available at https://github.com/colorifix/DyeDactic.
Code availability
All code to reproduce the workflow (except the colour index related analysis) is available at https://github.com/colorifix/DyeDactic; https://doi.org/10.5281/zenodo.17955211.
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Acknowledgements
The authors gratefully acknowledge the financial support from Innovate UK under the Knowledge Transfer Partnership (KTP) programme for KTP Associate funding (KTP13278). J.D.H. is supported by the Department of Science, Innovation and Technology (DSIT) and the Royal Academy of Engineering under the Chairs in Emerging Technologies scheme. We are grateful for access to the University of Nottingham high performance computer (HPC). We thank Ed Whitley for advice and help with experimental measurements and Helen Deeks for the code review.
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J.D.H. and R.J.W. conceived the idea of the project. D.S.K. carried out the calculations, wrote the computer code, performed the data analysis and experiments and prepared the manuscript draft. J.D.H., R.M. and R.J.W. supervised the research and edited the manuscript.
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D.S.K. is a KTP associate working with Colorifix Ltd. R.M. is an employee of Colorifix Ltd. All other authors declare no competing interests.
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Karlov, D.S., Marques, R., Wheatley, R.J. et al. DyeDactic workflow to predict halochromism of biosynthetic colourants. Commun Chem (2026). https://doi.org/10.1038/s42004-025-01881-9
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DOI: https://doi.org/10.1038/s42004-025-01881-9
