Improving the quantification of microbial cell abundances in subseafloor sediments through a combination of newly developed cell extraction and automated cell enumeration techniques

• Applicant: Dr. Jens Kallmeyer
• Subject Area: Palaeontology
• Term: from 2010 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 173158157

Exploration of the deep subseafloor biosphere is one of the most rapidly advancing fields of research within IODP. One the most fundamental parameters is the total amount of microbial biomass and its distribution with depth. This parameter can still not be quantified satisfactorily because of a lack of sensitivity of the current methods and the extremely time consuming manual analysis. The applicant recently developed a new cell extraction technique, which allows for a much lower detection limit by removing the cells semiquantitatively from the sediment, allowing more sediment to be used. Counting statistics improve significantly due to more cells being counted on each sample, however at the cost of increased processing time. Recent advances by the co-proponent in the field of automated sample processing allow for a much greater number of samples being processed. A combination of both techniques has the potential to greatly improve our understanding of the fine-scale dynamics of microbial population densities through better counting statistics and higher sample numbers, especially in extremely cell-poor environments. However, combining the two techniques is far from easy and requires careful modifications on both the cell extraction and the automated counting. The proposed visit will be used to work out the details for the combination of the two methods.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 527: Bereich Infrastruktur - "International Ocean Discovery Program" (IODP)
• International Connection: Japan
• Participating Person: Dr. Fumio Inagaki