Microbiological examination of sediment cores from the Peru margin (Leg 112) has produced highly significant results: (1) bacteria were present at all sediment depths sampled to 80 meters below seafloor (mbsf); (2) Bacteria were observed in the process of cell division at all but one depth to 80 mbsf; (3) Viable bacteria of different types (heterotrophs, sulfate-reducing, nitrate-reducing, methanogenic, and hydrocarbon oxidizing) have been isolated from many of the sediment samples, including those at 80 mbsf; and (4) Potential activity rates for sulfate reduction and methanogenesis have been determined and are consistent with the distribution of the respective bacteria and in-situ chemical profiles within the sediment. In combination, these results unequivocally demonstrate the presence and activity of bacteria within deep sediment layers.

Supplement to: Cragg, Barry A; Parkes, R John; Fry, J C; Herbert, R A; Wimpenny, Julian W T; Getliff, J M (1990): Bacterial biomass and activity profiles within deep sediment layers. In: Suess, E; von Huene, R; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 112, 607-619