Week 1 HW: Final Project Ideas

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1. What would I like to biomanufacture and why?

I want to use bacteria to “grow” colour without dyes. Specifically, I want to use bacterial cellulose to create thin, flexible films that get their colour from their physical structure rather than added dyes.

The idea is to grow cellulose and process it into cellulose noncrystals. These nanocrystals can self-assemble into a helical structure. The spacing within the structure determines which wavelengths of light are reflected, creating colour (Droguet et al., 2022).

The material would likely have 2 layers:

  • A black bacterial-cellulose backing containing melanin to help the colour stand out.
  • A colour-producing layer that reflects the desired wavelength of light.

The material could be cut into sequins or flakes for glitter. It could also be used as sheets for textiles and packaging.

Why?

I want to explore an alternative to conventional decorative materials. Dyeing can create wastewater problems (Walker et al., 2025). Pigments can depend on mined materials and energy-intensive processing. Conventional sequins and glitter are often made from plastic films such as PET or PVC. These can shed microplastics and make clothes harder to recycle (Droguet et al., 2022; Green et al., 2021).

This proposed experiment could offer an alternative, but I would still need to evaluate the finished material’s environmental impact.

I’m also drawn to the idea of making colour through biology. Someone can appreciate the colour before knowing anything about biomanufacturing. It would be an interesting way to share what I’m learning throughout the course.

2. What living system would I use?

I would use Komagataeibacter rhaeticus. It is a cellulose-producing bacterium associated with kombucha.

It can grow in a sugar-containing medium and produce a cellulose sheet at the surface of the liquid. Researchers have also engineered this bacterium to produce melanin-darkened cellulose (Walker et al., 2025).

There is also a published genetic toolkit for working with it (Florea et al., 2016).

Input

The culture would use sugar (glucose or sucrose) for growth and cellulose production. It would also need a growth medium for nitrogen and other nutrients. It would be grown at temperatures of around 26 to 30 degrees Celsius, with access to oxygen at the liquid surface to allow a cellulose sheet to form (Florea et al., 2016).

For the pigmented layer, I would also add L-tyrosine and copper ions to support melanin production, since tyrosinase is a copper-dependent enzyme tyrosinase (Walker et al., 2025).

Process

The bacteria would use the sugar to make cellulose, which would grow into a thin sheet. Unlike cellulose from plants, bacterial cellulose does not have lignin or hemicellulose, so less material needs to be removed afterwards (Florea et al., 2016).

An engineered strain would also produce melanin, which would darken the cellulose (Walker et al., 2025).

Outputs

There would be two main outputs:

  • Unpigmented cellulose for the colour-producing layer
  • Melanin-darkened cellulose for the backing.

3. How would I use automation?

The main experimental challenge would be finding conditions that reliably produce the colour I want. Factors such as concentration, pH, temperature, and humidity could all affect the final result (Droguet et al., 2022).

Testing these combinations manually would be slow. Small differences in dispensing or drying could make the results difficult to compare.

I would use a robotic liquid handler to prepare and screen different colour formulations (Petzold & Mukhopadhyay, 2025).

The proposed workflow would be:

  1. Prepare a set of formulations with the robot.
  2. Dry them under controlled temperature and humidity.
  3. Measure each film’s reflected colour.
  4. Use the results to choose the next set of formulations.

The benefit would be consistency, making it easier to understand why the colour changes.

4. How much would I need to make, and how long would it take?

(a) How much?

For a semester prototype, I would aim to make one 10 x 10 cm sample and approximately 200 small sequins.

These are starting estimates that I would update after making the first samples:

  • I would aim to grow about 10 g of dry bacterial cellulose. Most of it would be used for testing different formulations and replacing failed samples.
  • The final prototype would require approximately 3 g of dry bacterial cellulose (assuming about 70% of the total is used for testing).

Cellulose needed for the colour layer: 1.2 g

At a 50% conversion yield, this requires: 1.2 g / 0.5 = 2.4 g of dry bacterial cellulose

Cellulose needed for the black backing, assuming it requires half as much: 0.6 g

Total dry bacterial cellulose needed: 2.4 g + 0.6 g = 3.0 g

(b) How long?

Using 5 dishes in parallel, I would estimate it would take around 20 days to grow 10 g of dry cellulose, assuming each dish produces approximately 1 g every 10 days:

1 g x 5 dishes x 20 days / 10 days = 10 g

Including strain preparation, cellulose extraction, and colour testing, I would allow 8 to 12 weeks for the prototype.

5. What don’t I know yet?

1. Will bacterial cellulose produce reliable visible colour?

Bacterial cellulose may behave differently from the plant cellulose used in other literature (Droguet et al., 2022). This could affect how the material assembles. The black backing may also interfere with film formation.

I would screen different formulations and repeat successful ones across new batches to see if the colour can be produced reliably.

2. Will the material survive use as a sequin or decorative film?

The film could crack when bent, separate from its backing, or change colour with moisture.

I would test bending, washing, and humidity exposure. I would also track changes in colour and physical condition. If a protective treatment is needed, I would also test how it affects the material’s intended behaviour.

3. Can I produce enough cellulose at the assumed yield?

The production estimate depends on growth rate and cellulose extraction or recovery. Melanin production could reduce cellulose output.

I would measure dry-cellulose production and usable CNC recovery. These results would let me replace the assumptions with better estimates where needed.

References

Droguet, B. E., Liang, H.-L., Frka-Petesic, B., Parker, R. M., De Volder, M. F. L., Baumberg, J. J., & Vignolini, S. (2022). Large-scale fabrication of structurally coloured cellulose nanocrystal films and effect pigments. Nature Materials, 21(3), 352–358. https://doi.org/10.1038/s41563-021-01135-8

Florea, M., Hagemann, H., Santosa, G., Abbott, J., Micklem, C. N., Spencer-Milnes, X., de Arroyo Garcia, L., Paschou, D., Lazenbatt, C., Kong, D., Chughtai, H., Jensen, K., Freemont, P. S., Kitney, R., Reeve, B., & Ellis, T. (2016). Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain. Proceedings of the National Academy of Sciences, 113(24), E3431–E3440. https://doi.org/10.1073/pnas.1522985113

Green, D. S., Jefferson, M., Boots, B., & Stone, L. (2021). All that glitters is litter? Ecological impacts of conventional versus biodegradable glitter in a freshwater habitat. Journal of Hazardous Materials, 402, Article 124070. https://doi.org/10.1016/j.jhazmat.2020.124070

Petzold, C. J., & Mukhopadhyay, A. (2025). From bench to biofactory: High-throughput technologies and automated workflows to accelerate biomanufacturing. Current Opinion in Biotechnology, 94, Article 103320. https://doi.org/10.1016/j.copbio.2025.103320

Walker, K. T., Li, I. S., Keane, J., Goosens, V. J., Song, W., Lee, K.-Y., & Ellis, T. (2025). Self-pigmenting textiles grown from cellulose-producing bacteria with engineered tyrosinase expression. Nature Biotechnology, 43(3), 345–354. https://doi.org/10.1038/s41587-024-02194-3