RT Journal Article
SR Electronic
T1 Linking extracellular enzymes to phylogeny indicates a predominantly particle-associated lifestyle of deep-sea prokaryotes
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaaz4354
DO 10.1126/sciadv.aaz4354
VO 6
IS 16
A1 Zhao, Zihao
A1 Baltar, Federico
A1 Herndl, Gerhard J.
YR 2020
UL http://advances.sciencemag.org/content/6/16/eaaz4354.abstract
AB Heterotrophic prokaryotes express extracellular hydrolytic enzymes to cleave large organic molecules before taking up the hydrolyzed products. According to foraging theory, extracellular enzymes should be cell associated in dilute systems such as deep sea habitats, but secreted into the surrounding medium in diffusion-limited systems. However, extracellular enzymes in the deep sea are found mainly dissolved in ambient water rather than cell associated. In order to resolve this paradox, we conducted a global survey of peptidases and carbohydrate-active enzymes (CAZymes), two key enzyme groups initiating organic matter assimilation, in an integrated metagenomics, metatranscriptomics, and metaproteomics approach. The abundance, percentage, and diversity of genes encoding secretory processes, i.e., dissolved enzymes, consistently increased from epipelagic to bathypelagic waters, indicating that organic matter cleavage, and hence prokaryotic metabolism, is mediated mainly by particle-associated prokaryotes releasing their extracellular enzymes into diffusion-limited particles in the bathypelagic realm.