At Site 1159, four rock samples were collected as soon as the core liners were split to characterize the subsurface microbial community (Table T2). One sample is a breccia fragment (Sample 187-1159A-6R-2 [Piece 11, 73-75 cm]), and three are pillow basalt fragments composed of partially altered glass rinds and crystalline basalt interiors (Samples 187-1159A-2R-1 [Piece 7, 53-56 cm], 3R-1 [Piece 10A, 62-65 cm], and 7R-1 [Piece 25, 131-134 cm]). To sterilize them, the outer surfaces of the rock samples were quickly flamed with an acetylene torch, and enrichment cultures and samples for DNA analysis and electron microscope studies were prepared (see "Igneous Rocks" in "Microbiology" in the "Explanatory Notes" chapter).
Fluorescent microsphere tests were carried out for one rock core to evaluate the extent of contamination caused by drilling fluid (see "Tracer Test" in "Microbiology" in the "Explanatory Notes" chapter and Table T2). Pieces of rock were rinsed in nanopure water, the collected water was filtered, and the filter was examined for the presence of microspheres under a fluorescence microscope. Thin sections were used to examine the extent of contamination inside the sample. Microspheres were observed on the filter but not in the thin sections; this may be because the thin sections were almost fracture free.