Tracking Functional Microbiomes of The UKs Anaerobic Digestion Reactors
anaerobes.science is the home of the UK Anaerobic Digestion Microbiome Monitoring Project. It aims to collect weekly microbiome data for over a year from industrial-scale anaerobic digestion plants across the UK, therefore producing an unprecedented temporal genomic dataset from these reactors, along with detailed metadata on their operational conditions and output.
This data will be made freely available here (see Datasets), and will be used to aid our understanding of the science of anaerobic digestion, and of how the highly complex microbial communities inhabiting anaerobic digestion plants affect and are affected by operational conditions. This understanding may help us to better control the process and increase its efficiency.
There are currently 10 anaerobic digestion plants across the UK involved in the project. Anaerobic digestion is used for a variety of purposes and in different industries, and we have a cross-section of digesters, from industrial operations digesting large amounts of farm waste or dedicated biofuels to smaller digesters used on farms to degrade waste and produce energy and fertiliser.
Schematic of an AD plant, courtesy New Generation Biogas
Anaerobic Digestion (AD) is an important renewable energy technology involving the breakdown of waste products by microbes to produce biogas. This biogas, a mixture of methane and carbon dioxide, can be burned to produce energy. AD has the additional benefit of breaking down waste in an environmentally-friendly manner. The digested material can be used as fertiliser, and reduces the emission of methane, a potent greenhouse gas, into the atmosphere, since it is burned rather than being released over time from the waste.
Because of this, there is a lot of interest and investment in AD all over the world. In Germany, there are over 6000 operating AD plants; in China there are over 25 million biogas plants. The UK Department of Energy and Climate Change (DECC) states that the government aims to achieve about 0.3-0.4GW of power from AD by 2020; better understanding and control of the process will be crucial to achieving this goal.
Fluorescence microscopy image of methanogenic archaea.
Anaerobic Digestion is performed by complex communities of microbes, which use the energy and material gained from breaking down carbohydrates, proteins and fats to grow and reproduce. These materials are gradually broken down into smaller and smaller molecules, eventually producing carbon dioxide and methane. However, no one organism can perform all the steps of this task, so AD plants contain whole communities of microbes, which rely on each other to survive. The final step of this process, the production of methane, is performed by particularly interesting organisms, called methanogens. These look and act very similarly to bacteria, but are actually from a completely different branch of life called ‘Archaea’, discovered only a few decades ago. Genetically, they are as different from bacteria as they are from animals and plants.
The health of this complex ecosystem is crucial to the operation of AD plants. Changes in conditions can cause the community to change and reduce the efficiency of the digester; this is similar to how problems with the microbiota in a human gut can cause problems with digestion.
In this project we are going to use state-of-the-art genetic sequencing techniques on weekly samples from participating digesters. This will produce very large amounts of high-quality genetic data, which we will use to characterise which species of microbes inhabit the digesters, what their functions are, and, crucially, how these change over time and in response to changes in their environment.
The Human Microbiome Project - large-scale project characterising the microbes living in and on humans
The Earth Microbiome Project - aims to sequence microbial communities living in environments across the globe