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doi:10.2204/iodp.proc.314315316.124.2009 MicrobiologySample informationA total of 63 whole-round cores were taken from Holes C0002B and C0002D for microbiological analysis. Table T17 shows the depths of the three types of whole-round cores. Some of the whole-round cores were subsampled on board for cell fixing, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) extraction, and culturing studies. Onboard work mainly included preserving whole-round cores and subsamples for shore-based work, fixing cells for cell detection, and counting and setting up sulfate-reducing bacteria enrichment cultures. Cell detection with epifluorescence microscopySelected fixed cell samples were stained on board with double-stranded DNA-binding SYBR Green I stain. Cell counting was conducted on shore. Cells were detected in core samples to 1020 m CSF (Fig. F27). The number of cells ranges from 9.9 × 106 to 3.4 × 109 per cubic centimeter (Table T18). Some samples have a lot of matrix, which makes counting difficult. Cell abundance decreases drastically between samples at 58 and 79 m CSF and remains low in the sections below except for three samples at 203, 566, and 1020 m CSF. There is no clear relationship between geology and cell abundance. Cultivation experimentsEnrichment cultures were established during Expedition 315 with the aim to culture sulfate-reducing microorganisms. Cultures were monitored for sulfate reduction based on the formation of black iron sulfide precipitate, which indicates production of biogenic hydrogen sulfide in the iron-containing medium. During the expedition, no blackening of the growth medium was observed in any of the cultures from Site C0002 because of the short incubation time (up to only 1 week, depending on the sample). |
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