Projects/science - world/may 26, 2020

Spatially controlling attachment of functional proteins to bacterial cellulose using optogenetics

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About This Project

The bacterium Komagataeibacter rhaeticus has the ability to naturally produce bacterial cellulose (BC) which possesses many unique, highly useful properties suitable for a wide range of applications. We hypothesize that an optogenetic circuit in an engineered strain of K. rhaeticus grown in an optimized bioreactor can spatially control attachment of proteins to the surface of BC membranes to enable fine-tuning of these properties for different applications.

What is the context of this research?


While cellulose is best known as a plant product, some bacteria, most notably of the genus Acetobacter (a synonym for Komagataeibacter), can produce it as well. Bacterial cellulose (BC) is more pure than plant cellulose and possesses properties such as high porosity and moisture retention. These traits make BC attractive for wound dressing and tissue scaffolding compared to traditional materials.

Despite its innate benefits, BC does have shortcomings, such as lacking antimicrobicity. These shortcomings, however, can be solved by additional functionalization, such as by attaching antimicrobial peptides to the surface of BC. We plan to build off of Imperial College 2014 iGEM’s groundwork on functionalizing BC and use their genetic toolkit for engineering K. rhaeticus.


What is the significance of this project?


Bacterial cellulose (BC) has many applications, most notably in the fields of tissue engineering and biomedicine. The high tensile strength of cellulose microfibrils protects burn victims from bacterial infection as well as water loss through damaged skin tissue. BC is better at resisting tear than existing bandage materials on the market today, such as polyethylene and polyvinyl chloride. Precise spatial control of BC functionalization will allow for production of custom bandages that can modulate their properties to match the specific needs as they vary at different locations across a wound. Our functionalization mechanism may be utilized for a wide range of applications beyond biomed, such as environmentally-conscious production of textiles and other innovative alternative goods.


What are the goals of the project?


Our project aims to create a platform for precise, light-based control of bacterial cellulose functionalization. We will engineer K. rhaeticus to increase the functionality of BC by attaching fusion proteins via a cellulose binding domain. Levels of functionalization of the fusion proteins will be controlled with light via an optogenetic circuit. We will build a proof of concept that uses this process to spatially control the attachment of chromoproteins onto BC.

Production volumes will be improved through optimizing bioreactor conditions. Oxygen is a major limiting factor in production. Media enhancements, pH, and temperature optimization may also increase output. Additionally, we will explore metabolic engineering opportunities to increase production and reduce byproducts.

Distribution of money

Our budget is divided into three categories: lab operation, procedure costs, and bioreactor operation. Lab operation includes labware, lab consumables, and equipment maintenance.

The construction of our gene constructs, molecular cloning work, and production of bacterial cellulose in small-scale assays is a major development cost. This includes relevant molecular reagents, chemicals, gel and purification supplies, enzymes, and cells. Another part of our budget will go towards sequencing to confirm the assembly of our construct.

Lastly, construction of our bioreactor will incur significant costs — including parts and tubing, 3D printing filament, a simple control system, probes and sensors (for pH, dissolved oxygen, and temperature, etc.), and peristaltic pumps for nutrient delivery. There may be software costs for bioreactor and genetic modeling and control.