Do deep marine sediments host unusually stable enzymes?

Abstract

Microbial life persists in marine sediments up to several kilometers below the sediment-water interface. Microbes in this environment live tremendously slowly, with cell carbon turnover times on the order of years to thousands of years. Those rates are approximately six orders of magnitude slower than fast-growing cells in pure culture. These slow-but-nonzero metabolic rates and long apparent cell lifetimes imply that the enzymes produced by subsurface microbes must be comparably long-lived. Here we present enzyme assays performed in sediments up to 78 meters below the seafloor as part of International Ocean Discovery Program Expedition 347.