Page designed and maintained by Hazel Mottram.Last modified 25/01/02

Description of work

Living bacteria exist hundreds of metres below the sea bed and probably to depths where thermogenic geosphere processes occur. Current techniques to obtain and process samples are stretched to their limits at such depths, yet this is one of the newest most exciting interfaces on the planet.

Existing techniques used to quantify total bacterial populations (direct microscopy), their activity (incorporation of ³⁵S and ¹⁴C labelled substrates into bacteria and their metabolic byproducts) and to identify active organisms (incorporation of ¹³C labelled substrates into bacterial PLFA biomarkers and/or ¹⁶S-rRNA) will be optimised for the study of the deep subsurface.

The collaborative nature of the project will allow the development of novel or improved method which will be applied to deep sediment samples taken on ODP legs. In addition novel deep bacteria of potential biotechnological application will be isolated. Temperature limits for bacterial activities will be determined in thermal gradient experiments. This will enable a greater understanding of how this ecosystem functions at the biosphere:geosphere interface.

The latest molecular genetic techniques (DGGE) will be applied to these unique samples to obtain a detailed description of their diversity. Molecular probes will also be developed to rapidly identify and isolate specific organisms in mixed cultures and deep sediments. These isolated cultures will undergo biomarker characterisation. Biomarker profiles will complement results from a range of techniques (TOC, Rock-Eval pyrolysis etc) used to characterise the sedimentary organic matter in the deep sediment samples and those from thermal gradient experiments. Bacterial inputs to deep sedimentary organic carbon and their impact on maturation processes will be assessed and the interplay between biological and thermogenic processes will be defined.