Occurrence of bacteria in pelagic sediments collected during the mid-Pacific expedition

Abstract

Bacterial populations ranging from hundreds to thousands per gram wet weight were demonstrated in pelagic sediments (red clay and globigerina ooze) taken during the Mid-Pacific Expedition. The abundance of viable bacteria in these sediments decreased with core depth. Although certainly most important as geochemical and biological agents in surface sediments at the mud-water interface, living bacteria were found at the bottom of the longest cores examined, nearly 8 metres, representing material believed to have been deposited more than a million years ago. A few explanations are offered to account for the presence of bacteria in this material of great antiquity.