Most microbial life on earth exists as a collective entities, or 'biofilms'. These biofilms consist of the microbial cells and the extracellular biopolymers (EPS) they exude. The EPS serve many purposes of benefit to the microorganisms, but whereas EPS have received much attention in medical sciences, the science of EPS in soil is relatively undeveloped. Adding EPS to porous media (such as sand or soil) can' improve water-retention which is of great potential benefit to agriculture. ,It is not cost-effective to do this directly however due to the cost of deployment and physical incorporation with soil. Therefore it is more useful to identify managements that increase EPS indirectly using microbes already present in soil. These managements cannot be identified without the use of appropriate and meaningful analytical techniques that characterise the EPS produced by the soil microbial community. ' A range of extraction methods and measurements were compared, with the most representative selected to investigate i) triggers to EPS production ii) interplay between soil-nitrogen and carbon dynamics, and ii) the impact of EPS upon aggregate stability. Ultimately, an extraction method using cation exchange resin was selected. This method appeared to maintain membrane integrity of the majority of cells, thus minimising the likelihood of contaminating the EPS extracts with intracellular material. Using this method, EPS production in soil was shown to be affected by substrate availability, C:N ratio, hydrology, zinc contamination, and the nature of carbon substrates provided:1 Finally, the protein content of EPS was found to be closely related to aggregate stability, which in turn maintains soil functions critical to ecosystem services and agricultural productivity. This thesis represents a step towards understanding soil-native-EPS production: towards applied goals (such as improving soil water retention and understanding the consequences of agricultural managements) and advancing our fundamental knowledge of soil organic matter dynamics
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:616636 |
| Date | January 2013 |
| Creators | Redmile-Gordon, Marc |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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