At Site 1152, two rock samples (187-1152A-1R-1 [Piece 1A, 0-5 cm] and 187-1152B-4R-1 [Piece 12, 71-78 cm]) were collected to characterize the microbial community inhabiting this environment (Table T4). Both samples are fragments of pillow lava, consisting of a partly altered glassy margin and some of the more crystallized interior. Core 187-1152A-1R has a partly weathered, yellowish brown surface with small black spots of Mn oxides.
Two approaches to minimize drilling-induced contamination on the outer sample surface were followed at this site. For Sample 187-1152A-1R (Piece 1A, 0-5 cm), the outer surface of the core was split off with a hydraulic rock trimmer, and the remaining pieces were used for experiments. This method exposes the sample to oxygen for 45-60 min, and obligate anaerobes were not expected to grow. Nevertheless, this sample was treated as an aerobic sample and was only inoculated in three aerobic media and two nonreduced anaerobic media. In the nonreduced media, facultative anaerobes may grow.
For Sample 187-1152B-4R (Piece 12, 71-78 cm), the outer surface was quickly flamed with an acetylene torch, which proved to be the simplest and fastest sterilization method. This minimized the time the rock sample was exposed to oxygen to 20 min. After the sterilization, enrichment cultures and samples for DNA analysis and electron microscope studies were prepared as described in "Igneous Rocks" in "Microbiology" in the "Explanatory Notes" chapter.