Hydrolytic exoenzymes

The organic carbon of the plankton cell must first be buried to a sediment horizon below the penetration depth of sulfate. Here, the particulate organic material must be degraded by hydrolytic exoenzymes. The breakdown products are then fermented by bacteria in several steps to acetate, hydrogen and CO, which are ultimately converted to methane by methanogenic archaea. 

Occurrence of bacterial hydrolytic exoenzymes in plankton assemblages... 

Any enzyme catalyzing a hydrolytic reaction that occurs within a polymeric substrate molecule. Those enzymes acting at the terminus of a polymeric substrate molecule are called exoenzymes. 

Rates of supply may be controlled, in part, by the activity of hydrolytic enzymes that degrade combined molecules in dissolved or particulate organic matter to monomeric constituents prior to enzymatic transport into bacterial cells (Skoog et al., 1999 see also Chapter 13). At present, in situ rates of such exoenzymes have not been accurately measured, but enzyme potential has been estimated with the addition of artificial substrates in saturating... 

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