Petroleum-derived chemicals are used as building blocks to create a variety of products we take for granted in our day to day lives. And while these molecules have proven to be critical for modern society, their overuse has had significant negative environmental and societal impacts. Microbial biocatalysts play a prominent role in the future of renewable biomass degradation into bio-equivalent chemicals that can be used directly in established industrial processes. However, there is high cost to process raw biomass into a usable form which has remained a major obstacle in successfully implementing these techniques in industry.

During our brainstorming process we came up with the initial idea of using an engineered microbial community to effectively transform biomass into useful products. We were inspired by new research at our university on the expression of functional enzymes onto the S-Layer of certain strains of bacteria. We aim to use these new techniques together with traditional bacterial bio-catalytic pathways to make the processing and utilization of renewable biomass feedstocks cheaper and more efficient.

To accomplish this task, we are designing a two-part microbial community. One half will be responsible for transforming biomass feeds stalks such as lignin and cellulose into useful growth substrates. While the other half will focus on using these growth substrates for the production of useful products.

To create our biomass transforming bacterium, we will use the robust surface expression system in the bacterium Caulobacter crescentus to display biomass transforming enzymes, mimicking the cellulosomes and laccases found in natural biomass degrading bacteria. To create our production bacterium, we will engineer Escherichia coli, to produce violacein. Violacein is a high-value natural product with interesting pharmacological properties. It also has the benefit of being easily detected and quantified, allowing for the validation of our approach. When combined, these bacterial strains will be able to work together to degrade and valorize biomass.

So far our team has been working to characterize a bio-bricked β-carotene construct in E. coli in order to do an initial proof of concept, we have also been working on the violacein construct. Simultaneously we have been cloning several laccases and celluloses into the s-layer protein of C. crescentus. We hope to get functional expression of our enzymes onto the s-layer and characterize the enzymatic activity to build and active model for our system which we can test by growing the two bacteria together in minimal media with restricted carbon sources.