At Site 1155 five rock samples (Samples 187-1155A-2R-1 [Piece 1A, 0-3 cm], 187-1155B-2R-1 [Piece 6A, 60-63 cm], 187-1155B-3R-1 [Piece 6A, 30-32 cm], 187-1155B-5R-1 [Piece 14A, 120-123 cm], and 187-1155B-8R-1 [Piece 16A, 109-114 cm]) were collected to characterize the microbial community inhabiting this environment (Table T2). All samples are pillow basalt fragments, including both the partly altered glassy margin and the more crystalline interior. To sterilize them, the outer surfaces of the rock samples were quickly flamed with an acetylene torch. Enrichment cultures and samples for high-pressure enrichment, DNA analysis, and electron microscope studies were prepared (see "Igneous Rocks" in "Microbiology" in the "Explanatory Notes" chapter).
To evaluate the extent and type of contamination caused by drilling fluid, fluorescent microsphere tests were carried out for three rock cores and surface seawater was collected for DNA characterization (see "Tracer Test" in "Microbiology" in the "Explanatory Notes" chapter and Table T2). One or two pieces from each core were rinsed in nanopure water, the collected water was filtered, and the filters were examined for the presence of microspheres under a fluorescence microscope. Thin sections were used to examine the extent of contamination inside the samples. Microspheres were detected on all three filters but were not seen in any of the thin sections.