Science & Tech · Science & Environment · 2 hrs ago
Bacterial enzyme tests show the difficulty of improving photosynthesis
Researchers tested about 15,000 versions of a bacterial Rubisco enzyme in photosynthetic cells.
Rubisco helps plants and some bacteria turn carbon dioxide into the first building blocks of food.
It can also capture oxygen, a less useful reaction that costs cells energy to undo.
About 8% of single-change versions helped cells grow faster, while fewer than 1% of versions with several changes did.
Changes that worked alone often did not work when combined, and computer models struggled to predict which combinations would succeed.
The enzyme came from a bacterium, not a plant, so crop use would require tests in plant cells and whole plants.
The results give researchers a list of changes to investigate, but whether they can improve crops remains to be tested.
Researchers screened about 15,000 bacterial Rubisco variants to test whether changes could improve photosynthesis.
Some single changes helped the enzyme, but most combinations of changes did not improve cell growth.
Computer models also struggled to predict which combinations would work.
The study used a bacterial enzyme, so its results would need further testing in plant cells and whole plants before any crop application.
- Who
- A team led by Paul Hudson of KTH Royal Institute of Technology, with Ute Hoffmann and Axel Knave as co-first authors.
- What
- Researchers tested altered bacterial Rubisco enzymes in photosynthetic cells to assess whether they could improve growth.
- When
- Published on November 14, 2026. The research date is not stated.
- Where
- The experiments used Synechocystis cells; the research involved KTH Royal Institute of Technology in Stockholm and collaborators in Spain and Japan.
- Why
- The team aimed to make Rubisco faster or reduce its oxygen-capturing activity while retaining carbon dioxide capture.
This story does not have two clearly opposing sides.
The team tested single changes and combinations of changes in bacterial Rubisco.
The pooled cyanobacteria grew for 12 generations in bioreactors, with or without oxygen in the gas feed.
The team found that about 8% of single-swap variants grew faster than cells carrying the starting enzyme, compared with under 1% of multi-change variants.
- Variants screened
- About 15,000
- Enzyme source
- Gallionella, a bacterium
- Test cells
- Synechocystis, a photosynthetic bacterium
- Combination design
- 16,200 possible combinations across seven positions
- Single-swap growth
- About 8% grew faster than cells carrying the starting enzyme
- Multi-change growth
- Under 1% grew faster than cells carrying the starting enzyme
What people are saying
Our idea was to take these fast Rubiscos and make them even faster, or at least reduce their oxygenation rate while retaining a high carboxylation rate.
But they also catalyze the oxygenation reaction more readily, meaning that they are less selective for carbon dioxide.