Engineering Rhodopseudomonas palustris for enhanced biohydrogen production

Fossil fuels (oil, coal, and natural gas) dominate global energy sources but emit CO2, contributing to climate change. Their extraction harms the environment and is finite. Transitioning to cleaner, sustainable energy is essential. Renewables like wind, solar, hydro, and geothermal, plus alternative fuels (e.g., hydrogen and biofuels), are gaining traction. Hydrogen is promising. It's carbon-neutral and versatile, aiding decarbonization. Current hydrogen production, though, relies on fossil fuels, emitting CO2. Clean, renewable options like biohydrogen, produced biologically from organic matter using microbes, offer lower carbon footprints, energy efficiency, and waste management solutions.Microbial electrochemical technologies, notably microbial electrochemical cells (MECs), are used for biohydrogen production. Challenges include enhancing yield and production rate. Addressing these hinges on understanding microbial communities involved in biohydrogen production.Rhodopseudomonas palustris or R. palustris is one of the most attractive and potential candidates commonly utilised in MECs for biohydrogen production. It can fix both carbon and nitrogen. Hydrogen production is the side product of nitrogen fixation. The knowledge gap lies in how the metabolic modules of nitrogen fixation and hydrogen production are controlled in this bacterium. In this context, my project focuses on understanding the interaction among the genes responsible for hydrogen production in R. palustris and engineer them for enhanced biohydrogen production. Work package 1 Task 1.1- Characterisation of different industrial wastewater streams Wastewater from such industries will be explored and characterised for organic content. This will help to identify the wastewater streams that are rich in organic content. Task 1.2- Assessment of different strains of R. palustris that have shown hydrogen production
Previously studied strains of R. palustris will be inoculated in the different waste streams and the extent of hydrogen production will be documented, enabling us to identify the best hydrogen producing strain. Work package 2
Task 2.1- Identification of differentially expressed/regulated pathways The best hydrogen producing strain will be grown under nitrogen limiting or non-limiting conditions and will be subjected to comparative proteomic and transcriptomic analysis.Task 2.2- Validation of genes/regulatory proteins involved in hydrogen production Newly identified pathway components will be subjected to gene inactivation and later functional complementation to elucidate their role in H2 production. Work package 3 Task 3.1- Biological engineering Once the regulation of differentially expressed genes in the best characterised strain of R. palustris responsible for H2 production has been identified, the potential candidate genes will be subjected to further genetic modification (plasmid- based overexpression, genome integration, deregulation, deletion) with the aim of enhancing H2 production. Work package 4- Assessing hydrogen production in engineered R. palustris' strain in MEC. Task 4.1- MEC construction For this task, a two-chambered MEC system separated by a PEM (Nafion (Du Pont) will be used. Task 4.2- Evaluation of genetically engineered R. palustris' strain in MEC for improved hydrogen production The genetically modified strain vs its wildtype will be analysed for hydrogen production in the MEC constructed above. Work package 5 Task 5.1- With the aim to achieve improved hydrogen production, the MEC reactor will be optimised on the following factors:pH, Temperature, Electrode material. Work package 6 Task 6.1 Performing LCA To assess the environmental impact of MEC-based microbial hydrogen production compared to traditional methods, an LCA, from raw material utilisation to disposal, can be executed

This CDT will deliver impact aligned to the following agendas:

People
A2P will provide over 60 PhD graduates with the skill sets required to deliver innovative sustainable products and processes into the UK chemicals manufacturing industry. A2P will inspire and develop leaders who will:
- understand the needs of industrial end-users;
- embed sustainability across a range of sectors; and
- catalyse the transition to a more productive and resilient UK economy.

Economy
A2P will promote a step change towards a circular economy that embraces resilience and efficiency in terms of atoms and energy. The benefits of adopting more sustainable design principles and smarter production are clear. For example, the global production of active pharmaceutical ingredients (APIs) has been estimated at 65,000-100,000 tonnes per annum. The scale of associated waste is > 10 million tonnes per annum with a disposal cost of more than £15 billion. Consequently, even a modest efficiency increase by applying new, more sustainable chemical processes would deliver substantial economic savings and environmental wins. A2P will seek and deliver systematic gains across all sectors of the chemicals manufacturing industry. Our goals of providing cross-scale training in chemical sciences with economic and life- cycle awareness will drive uptake of sustainable best practice in UK industry, leading to improved economic competitiveness.

Knowledge
This CDT will deliver significant new knowledge in the development of more sustainable processes and products. It will integrate the philosophy of sustainability with catalysis, synthetic methodology, process engineering, and scale-up. Critical concepts such as energy/resource efficiency, life cycle analysis, recycling, and sustainability metrics will become seamlessly joined to what is considered a 'normal' approach to new molecular products. This knowledge and experience will be shared through publications, conferences and other engagement activities. A2P partners will provide efficient routes to market ensuring the efficient translation and transferal of new technologies is realised, ensuring impact is achieved.

Society
The chemistry-using industries manufacture a rich portfolio of products that are critical in maintaining a high quality of life in the UK. A2P will provide highly trained people and new knowledge to develop smarter, better products, whilst increasing the efficiency and sustainability of chemicals manufacture.
To amplify the impacts of our CDT, effective public engagement and technology transfer will become crucially important. As a general comment, 'sustainability' styled research is often regarded in a positive light by society, however, the science that underpins its effective implementation is often poorly appreciated. The University of Nottingham has developed an effective communication portfolio (with dedicated outreach staff) to tackle this issue. In addition to more traditional routes of scientific communication and dissemination, A2P will develop a portfolio of engagement and outreach activities including blogs, webpages, public outreach events, and contribution of material to our award-winning YouTube channel, www.periodicvideos.com.

A2P will build on our successful Sustainable Chemicals and Processes Industry Forum (SCIF), which will provide entry to networks with a wide range of chemical science end-users (spanning multinationals through to speciality SMEs), policy makers and regulators. We will share new scientific developments and best practice with leaders in these areas, to help realise the full impact of our CDT. Annual showcase events will provide a forum where knowledge may be disseminated to partners, we will broaden these events to include participants from thematically linked CDTs from across the UK, we will build on our track record of delivering hi-impact inter-CDT events with complementary centres hosted by the Universities of Bath and Bristol.