Peptidase and glucosidase activities from mesocosm and bulk water incubations from waters taken aboard the R/V Endeavor in the Western North Atlantic during the research cruise EN683 in May and June, 2022.

This dataset includes the measurements of leucine aminopeptidase, glucosidase, and endo-acting (mid-chain cleaving) peptidase activities from bulk and mesocosm incubations from waters taken aboard the R/V Endeavor in the Western North Atlantic during the research cruise EN683 (2022-05-24 to 2022-06-12). Waters for bulk incubation were taken at three sites and various depths, mesocosm incubations were taken at two sites and two depths.

This research tested the hypothesis that the mechanism of polysaccharide processing is related to the cost to a cell of producing the enzymes required for its hydrolysis, and the probability that a cell will receive sufficient return on investment for producing the enzymes. Our conceptual model suggests that external (extracellular) hydrolysis is favored when organic matter is abundant, or when enzyme production costs can be shared (e.g., on particles, in biofilms); selfish uptake (hydrolysis without production of low molecular weight products in the environment) would be a better strategy when high molecular weight (HMW) organic matter is scarce, and particularly when the HMW organic matter is very complex.

Seawater was sampled from four depths at our initial station, and the deep chlorophyll maximum and bottom water from two subsequent stations differing in typical extent of primary productivity.

We incubated mesocosms of seawater from the deep chlorophyll maximum and from bottom water from two stations differing in typical extent of primary productivity. Organic matter availability was amended by adding high molecular weight organic matter (dissolved and particulate) from diatoms, or by adding the polysaccharide fucoidan, or by adding the polysaccharide arabinogalactan. Amendments were performed in triplicate mesocosms, while one mesocosm was left unamended for a total of ten mesocosms from each depth and station tested

These data help test this model because they provide information about the activities of exo-acting glucosidases and an exo-acting peptidase, plus endo-acting peptidases, all of which are used to hydrolyze high molecular weight organic matter. Activities of these enzymes differed by station as well as by depth