19-ERACoBioTech SYNBIOGAS: Synthetic landfill microbiomes for enhanced anaerobic digestion to biogas

Lead Research Organisation: Bangor University
Department Name: Sch of Natural Sciences

Abstract

Lignocellulosic plant biomass is the most abundant waste product generated by society, agriculture and industry. By 2025, global cities will
generate approximately 2.2 billion tonnes of solid waste biomass per year, with significant impacts upon health and the economy at both
local and global scales. Natural communities of microorganisms (microbiomes) convert waste biomass to methane-rich biogas that can be
used as a sustainable and renewable green-energy source to generate electricity, heat and power, and biomethane for injection into the
national gas grid and production of transport fuels. Anaerobic digestion (AD) plants and landfill sites are engineered environments where
these microbial processes are harnessed for waste decomposition and biogas production. The EU is the largest global producer of biogas
from biomass, with over 17,000 AD plants, and consequently, the microbiological conversion of solid waste residues to biogas in AD plants
and landfill sites presents an unprecedented opportunity to leverage key enabling technologies for a sustainable bio-based economy for
green-energy production. In turn, conversion of waste biomass to biomethane will mitigate the escalating environmental and social impacts
of waste residues. However, the metabolic function of microorganisms responsible for anaerobic digestion is poorly understood, and most
previous studies have focused on animal gut microorganisms that are typically used to incoluate microorganisms into anaerobic digestion
plants as slurry. One of the major bottlenecks to industrial application of microorganisms for biomass-conversion is low substrate specificity,
low temperature tolerance, and an inability to perform optimally under reaction conditions. Natural microorganisms found in landfill sites
represent an unexplored repository of biomass-degrading enzyme diversity with the potential to enhance existing industrial
biomass-conversion processes. Landfill microorganisms are already adapted to engineered environments, mineralise diverse solid waste
types, produce methane-rich biogas, and are therefore good candidates for the bioaugmentation of anaerobic digestion processes. The SYNBIOGAS consortium is an academic-industry partnership that will integrate diverse and cutting-edge technological, analytical,
engineering and computational approaches for characterisation of the landfill biomass-degrading microbiome. Microbial isolations, DNA
sequencing, enzyme characterisation and computational modelling of landfill microbial biomass-conversion processes will inform the design
and validation of optimised synthetic landfill microbiomes (SLMs) for enhanced waste biomass-conversion in AD plants and landfill sites, and
to develop applications of the SLM that can be readily adopted by industry. Engineering biomass-degrading microbiomes is a new research
frontier with many novel applications, including bioaugmentation and optimisation of biomass conversion in AD and landfill systems towards
an enhanced bio-based economy for waste management, environmental protection, and sustainable intensification of renewable energy
generation.

Technical Summary

The landfill microbiome represents an unexplored repository of biomass-degrading enzyme diversity to enhance existing industrial
biomass-conversion processes and identify new hydrolase enzymes of relevance for industrial biotechnology processes. This project aims to utilise a systems biology analysis of biomass-conversion by landfill microbiota, combining novel technological, analytical and computational approaches for microbiome characterisation, in silico discovery and validation of novel enzymes, and process modelling for the design of optimal synthetic biomass-converting microbiomes. Ultimately, the research will generate synthetic landfill microbiomes (SLMs) designed for bioaugmentation of landfill sites and anaerobic digestion plants for enhanced biomass conversion and biogas generation, enabling a progression in TRL in this sector. In addition, we will utilise life cycle assessment and cost benefit analysis approaches to demonstrate the potential industrial benefits of our process model and synthetic microbiome, and will generate a road map for industry adoption of the new technology. The research leverages new approaches to understanding fundamental questions regarding the ecological factors that drive syntrophic interactions between anaerobic biomass-degrading microbiota.

Planned Impact

The landfill microbiome represents an unexplored repository of biomass-degrading enzyme diversity to enhance existing industrial
biomass-conversion processes and identify new hydrolase enzymes of relevance for industrial biotechnology processes (Ransom-Jones et al.,
2017). This project will provide the first systems biology analysis of biomass-conversion by landfill microbiota (WP1-3) combining novel
technological, analytical and computational approaches for microbiome characterisation (WP1), in silico discovery and validation of novel
enzymes (WP2) and process modelling for the design of optimal synthetic biomass-converting microbiomes (WP3). Ultimately, the research
in WP's 1-3 will generate synthetic landfill microbiomes (SLMs) designed for bioaugmentation of landfill sites and anaerobic digestion
plants for enhanced biomass conversion and biogas generation in WP4, enabling a progression from TRL2 to TRL6 through the project
(Figure 2). In WP5, we subsequently utilise life cycle assessment and cost benefit analysis approaches to demonstrate the potential
industrial benefits of our process model and synthetic microbiome, and will generate a road map for industry adoption of the new
technology. The research leverages new approaches to understanding fundamental questions regarding the ecological factors
that drive syntrophic interactions between anaerobic biomass-degrading microbiota.
Synthetic biology approaches for the engineering of biomass-degrading microbiomes is a new research frontier with many
novel applications, including bioaugmentation and optimisation of biomass conversion in AD systems towards an enhanced bio-based
economy for waste management, environmental protection and sustainable intensification of renewable energy generation.
Previously, laboratory-based landfill bioreactor experiments undergoing bioaugmentation with natural compost microorganisms demonstrated improved biomass degradation from 65% to 99%, and increased biogas generation (Kinet et al., 2016). The success of
bioaugmentation for biomass conversion with relatively undefined microbial populations from natural environments in laboratory reactors is
encouraging; however, such approaches have not been extensively validated and demonstrated in relevant industrial environments (i.e. AD
plants and landfills), and SLMs have not previously been designed and tested. Consequently, the opportunity to (i) directly manipulate
biomass-converting microbiota through characterisation, process modelling and the design of more sophisticated synthetic microbiomes,
and (ii), industrial application/validation of SLMs for enhanced biogas generation, in the SYNBIOGAS project is a tantalising challenge, with
significant potential to provide a paradigm shift in waste biomass conversion, green-energy production and waste management.
The SYNBIOGAS project is directly relevant to the CoBioTech call, and will develop a biotechnological application (synthetic landfill
microbial communities for enhanced biomass conversion to biogas) with potential for strong economic and social impacts towards at
sustainable bio-based economy. Our integration and development of the approach with industry partners ensures that our research has high
potential for commercialisation and industry adoption through achieving high levels of technology readiness (TRL 2-6). Social impacts
include sustainable options for waste management, reduce environmental impact of waste biomass, and the development of key enabling
technologies for sustainable green-energy generation with key economic benefits. Tangible outputs would include: novel CAZYmes with
enhanced catalytic activity and substrate specificity; high resolution datasets on SLM activity; world-leading metabolic process models of
anaerobic digestion processes; validated biotechnological applications of SLMs for AD bioaugmentation; life cycle assessment and a
stakeholder roadmap for technology implementation.

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