Application of multi-omics to identify and target microbial bloom control in legacy nuclear ponds

Background The safe operation of nuclear storage ponds is crucial to the continued provision of low carbon nuclear power to the UK, while decommissioning of legacy pond systems from historic operations remains a significant £multi-billion challenge to the industry. Optimising the management and treatment of the legacy ponds on the Sellafield site is crucial to reduce the hazards, reduce the cost to the tax-payer and protect the environment. However, the impact of microorganisms on plant operations is becoming evident, as the formation of microbial blooms in legacy ponds leads to reduced visibility within these facilities and fouling of downstream water treatment systems. As a result, controlling microbial growth is of growing importance, to keep decommissioning schedules on time and to budget. Recent work from the Manchester Geomicrobiology group, via collaborations with Sellafield Ltd. and the National Nuclear Laboratory, have identified discrete microbiomes in a network of hydraulically-linked legacy ponds (see references above). For example, cutting edge DNA-sequencing and metabolomic profiling has identified photosynthetic algae (MeGraw et al. 2018) and cyanobacteria (Foster et al. 2020a) in outdoor ponds, adapted to high radiation levels and other extremes (e.g. high pH) associated with the ponds, and potentially playing a role in controlling the fate of priority radionuclides (MeGraw et al. 2018 and Foster et al. 2020b). In contrast the low light intensities associated with indoor ponds, has not supported the widespread growth of photosynthetic communities, resulting in unique microbiomes sustained by hydrogen (generated through radiolysis reactions; Ruiz-Lopez et al, 2020). These studies have extended our knowledge of extremophile microbiology in engineered environments, and have also helped underpin control strategies, for example through carefully controlled purging cycles (Foster et al, 2020a).

Research questions and objectives This new study will focus on a closed-pond system, that has proved susceptible to microbial blooms, but cannot be controlled by purge systems. Recent IAA work supported by EPSRC has resulted in the identification of a discrete microbiome in this pond, and helped fine-tune a novel species-specific sonication approach for biomass control (featured in a DEES Impact Case being developed for REF). We now wish to build on these positive initial results with Sellafield and NNL, via a new EPSRC CASE project which will:
1. Use DNA-based high-throughput 16/18S rRNA gene sequencing to monitor long-term operation of the pond and help fine-tune targeted sonication treatments.
2. Apply complementary multi-omics approaches to study adaptation strategies within the pond.
3. Develop culture-based approaches to (i) confirm adaptation strategies in carefully constrained laboratory systems, (ii) quantify the impacts of microbial colonisation on radionuclide fate, and finally (iii) test control strategies e.g. biocide treatments to augment sonication.

Methods and training A cross-disciplinary approach will be adopted with training in techniques including culture-based microbiology, DNA extraction and sequencing (16S/18S rRNA and genome sequencing), bioinformatics, transcriptomic and proteomic analyses, geochemical and radiochemical profiling, and cutting-edge imaging and spectroscopy as appropriate. The student will work at various scales, from small-scale laboratory experiments, through to larger industrial scale culture systems, to verify control measures with the CASE partner (Sellafield Ltd).

This project aligns strongly with the need to deliver highly trained environmental scientists, able to work with real nuclear materials from site, and able to contribute to significant cost savings in the decommissioning of UK nuclear sites, including the £multibillion costs associated with managing and decommissioning Sellafield.