The Power of Closeness – the importance of microbial cooperation for the production of biogas

Senast ändrad: 15 september 2020

Maria Westerholm

Biogas is a unique asset for society. As it involves transforming waste into renewable energy and biofertilizer the production of biogas has to be seen as a major player against climate change and on the path towards environmental sustainability. Energy supply, local jobs and linking urban and rural areas are other valuable socio-economic benefits. In practice, biogas is produced by a large number of microorganisms that break down organic materials in an oxygen-free environment, a process called anaerobic digestion. This process occurs in nature but can be optimized and controlled in an anaerobic digester. Anaerobic digesters also allow capturing of biogas, that is used to replace fossil fuel in heating/cooling, electrical power generation and transportation. Biogas already plays an important role in the Swedish and European renewable energy sector. However, the technology is currently not used to its full potential and the production can increase significantly.

Several organic wastes from agriculture, households, and food industries contain proteins, and thus have high biogas potential. The remaining material after anaerobic degradation of these wastes is also a nutrient-rich biofertilizer. However, high protein content can be a major drawback in biogas systems, due to formation of ammonia during protein degradation. Ammonia is toxic to many microorganisms and thus often gives rise to process instability and decreased biogas yields. Development of ammonia-tolerant communities that rely on syntrophic (cross-feeding) microorganisms has shown to effectively overcome the most severe disturbances. Despite that syntrophic microorganisms are key microbial players in many biogas systems they are clearly understudied, mainly since commonly applied cultivation techniques disrupt their co-operative behavior, which is difficult to re-create.

My research vision is to tackle these challenges by develop enrichment and miniaturized cultivation systems that mimic the natural conditions of the syntrophic microbes. I will also take advantage of, and further develop, recent advances in in-situ detection and molecular analyses to study the microbial activity. Collectively, these approaches will enable studies of the syntrophic microorganisms in an environment that maintain the syntrophic interactions intact, while redundant microorganisms are diminished. By conducting research both on applied and fundamental aspects, I aim to reveal the capability of syntrophic microbes and most importantly uncover “how to enhance their activity”. I will achieve this by focus on bringing syntrophic microorganisms into close proximity in multicellular aggregates (often referred to as biofilms or flocs). Past scientific discoveries and observations made during cultivating the syntrophic microorganisms, strongly indicate an importance of physical closeness between the cooperating microorganisms for their degradation of acids to biogas. I will ecipher the key microbial, environmental and physical factors that promote syntrophic aggregate formation. The factors that enhance aggregation of syntrophic communities and enhance the rate of acid-degradation will be introduced into anaerobic digesters, with the prospect to improve biogas yield under high ammonia-stress.

My long-term ambition is to understand the role of syntrophic microorganisms and continue to be inspired by their capacities to develop highly productive biotechnological systems for biogas formation. I look forward to apply my skills to further find solutions to improve production of renewable energy, contributing to the arms race against climate change. My prospect is also to increase the fundamental understanding of syntrophic ecology and physiology, which will have many possible applications in other biotechnologies with great expansion potential in future work of building biomass-based platforms.