Thermophilic bacterial activity in a deep-sea sediment from the Pacific Ocean

Thermophilic bacterial activity was detected in a deep-sea sediment sample from the South Pacific Ocean at 12 degrees S, 135 degrees W, an area of the seafloor distant from known hydrothermal venting. Incubation of sediments amended with C-14-glutamate indicated maximal respiration (evolution of (CO2)-C-14) and assimilation (incorporation of C-14 into acid-precipitated macromolecules) of substrate at 52 degrees C, relative to 4 and 22 degrees C. A parallel experiment at another site (2 degrees S, 140 degrees W) yielded no evidence of thermophily. Thermophilic bacteria may be deposited in deep-sea sediments following their long-distance dispersal from hydrothermal vents (e.g. the East Pacific Rise and other sites), via either continuous venting or formation of megaplumes.