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Scanning electron microscopy and confocal laser scanning microscopy images of biofilms formed on the surface of the sand within the Biocell following different influent pH values of substrate applied to the biofilm. Structural components of the biofilms include β‐1,4 and ‐1,3 polysaccharides (blue), lipids and hydrophobic sites (yellow), β‐mannopyranosyl and β‐glucopyranosyl sugars (red), protein (green), total cells and extracellular DNA (pink).
Source publication
Extremes of pH present a challenge to microbial life and our understanding of survival strategies for microbial consortia, particularly at high pH, remains limited. The utilization of extracellular polymeric substances within complex biofilms allows micro‐organisms to obtain a greater level of control over their immediate environment. This manipula...
Citations
... Microniche distribution is also difficult to predict due to the many potential interactions that may underpin their development, and high-resolution techniques are required to monitor activities across very small (micron) scales within highly complex matrices. The importance of understanding the pH limits of microbial activity, heterogeneity, and the formation of microniches within a high pH GDF is critical to the safety case and has been demonstrated in analogue biofilm systems (Charles et al. 2022). ...
Decades of nuclear activities have left a legacy of hazardous radioactive waste, which must be isolated from the biosphere for over 100,000 years. The preferred option for safe waste disposal is a deep subsurface geological disposal facility (GDF). Due to the very long geological timescales required, and the complexity of materials to be disposed of (including a wide range of nutrients and electron donors/acceptors) microbial activity will likely play a pivotal role in the safe operation of these mega-facilities. A GDF environment provides many metabolic challenges to microbes that may inhabit the facility, including high temperature, pressure, radiation, alkalinity, and salinity, depending on the specific disposal concept employed. However, as our understanding of the boundaries of life is continuously challenged and expanded by the discovery of novel extremophiles in Earth’s most inhospitable environments, it is becoming clear that microorganisms must be considered in GDF safety cases to ensure accurate predictions of long-term performance. This review explores extremophilic adaptations and how this knowledge can be applied to challenge our current assumptions on microbial activity in GDF environments. We conclude that regardless of concept, a GDF will consist of multiple extremes and it is of high importance to understand the limits of polyextremophiles under realistic environmental conditions.
