Design

In the process of designing the route from cellulose to StyGreen, there are many factors to consider. There are several approaches that can be taken to degrade cellulose, metabolic pathways to styrene as well as different interesting sources of cellulose. Discussions with many experts have aided us in making the right choices or adjustments during the design process. Furthermore, we connected with the upstream and downstream processes of our design and approached different stakeholders, connecting our project to cellulose suppliers and styrene buyers.

The production of StyGreen from cellulose is a multi-step pathway. As such, we have the choice of using either one or multiple organisms to perform the different reactions. For example, we could engineer a cellulose degrading organism and a styrene producing organism; these organisms can be co-cultured to produce styrene from cellulose. However, after discussing this idea with experts, we concluded that creation of a single organism performing both steps would be the most efficient and industrially desirable choice. In this manner, we produce a consolidated bioprocessing system which is not currently available. The combined process saves substrate, raw materials and utilities such as separate cellulase enzyme production. Moreover, the complete process could take place in one reactor and, in case of higher overall efficiency, this results in a reduced reactor volume and thus lower capital investment [A]. Hence, our ultimate goal is the production of a single robust cell factory that can grow on cellulose and produce styrene effectively in an industrial bioreactor setting.

Besides ‘wet lab’ experiments, we also modelled parts of our system in the 'dry lab' with help from experts to substantiate or improve our design. Want to know more details about our design? Click on the questions below to find out!

• Design (click me!)

  Click on the icons in the timeline, and find out about all the insights we gained from our stakeholders and how the dialogues shaped our project.

  

  Cellulose input

  • 1.1 What is a good cellulose source for our product?
    Something something
  • 1.2 How do we preprocess the cellulose-containing biomass for optimal use?

  Cellulose towards glucose

  • 2.1 Which enzymes do we need to degrade cellulose effectively?
  • 2.2 What is a mini-cellulosome?

  Glucose towards StyGreen

  • 3.1 How to convert glucose into styrene?

  Host strain

  • 4.1 Why Saccharomyces cerevisiae?
  • 4.2 How do we genetically modify S. cerevisiae?

  Further improving the process towards glucose

  • 5.1 How to adapt the expression system for sustained growth on cellulose?

  Further improving the process towards StyGreen

  • 6.1 How to improve the styrene yield?

  Final strain optimization

  • 7.1 How to further improve our StyGreen producing strain?
  • 7.2 How do we combat styrene toxicity?

  Experimental plan to test designs

  • 8.1 How do we detect cellulase activity?
  • 8.2 How do we detect styrene production?
  • 8.3 How do we test our strain?

  Upscaling towards a bioreactor and styrene harvesting

  • 9.1 How to sustainably upscale towards application in a bioreactor