Fermenting syngas to biodegradable plastics

Syngas, derived from waste biomass, is a toxic, corrosive and explosive mixture of CO, H2 and CO2. Let’s feed it to microbes! My aim is to ferment is to PHA’s.

Aim of the project

In a world with polluted oceans and rising greenhouse gasses, having a cheap, renewable and biodegradable form of plastic could benefit both nature and humanity. My project aims to contribute to that.


The feedstock that has been selected for this project is synthesis gas (or syngas), a gaseous mixture generated during the gasification of carbonaceous materials. Advances in biomass gasification are making syngas production from this renewable feedstock increasingly viable. Bio-based syngas does however contain contamination like sulfur compounds that make chemical conversion difficult. Biological conversion avoids these issues, because some of these contaminants can be used by microbes as nutrients.

Focus of the project

Currently the array of products that can be microbiologically produced from syngas is narrow. Only small molecules like ethanol, acetate and butanediol are feasible using classic fermentation techniques. In this project we will study the production of large polymers from syngas. This is achieved through deviating from standard fermentation techniques (one microbe, one substrate) and moving to co-cultures.

In a co-culture, microbes work together to expand their metabolic capabilities. The product of microbe A acts as the substrate for microbe B. This way a higher product complexity can be achieved in a single reactor vessel.

This study focusses on establishing a syngas fermenting co-culture that accumulates PHA’s. These are large polyester molecules that some microbes can accumulate under specific conditions. Research topics include: studying monocultured microbes under co-culture simulating conditions. Microbe-microbe interactions. Feedstock-microbe interactions and feedstock/microbe-product interactions.


If you are interested in the project please contact Martijn Diender or Diana Machado de Sousa.