Bacterial Versus Archaeal Origin of Extracellular Enzymatic Activity in the Northeast Atlantic Deep Waters

• Published in: Microbial Ecology
• Main Authors: Baltar, Federico, Arístegui, Javier, Gasol, Josep M., Yokokawa, Taichi, Herndl, Gerhard J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2013
• Subjects: Northeast Atlantic
• Online Access: http://hdl.handle.net/10261/75346; https://doi.org/10.1007/s00248-012-0126-7

12 pages, 4 figuraes, 2 tables We determined the total and dissolved extracellular enzymatic activity (EEA) of α-glucosidase and β-glucosidase (AGase and BGase), alkaline phosphatase (APase) and leucine aminopeptidase (LAPase) activities in the epi-, meso- and bathypelagic waters of the subtropical Northeast Atlantic. EEA was also determined in treatments in which bacterial EEA was inhibited by erythromycin. Additionally, EEA decay experiments were performed with surface and deep waters to determine EEA lifetimes in both water masses. The proportion of dissolved to total EEA (66–89 %, 44–88 %, 57–82 % and 86–100 % for AGase, BGase, APase and LAPase, respectively) was generally higher than the cell-associated (i.e., particulate) EEA. The percentage of dissolved to total EEA was inversely proportional to the percentage of erythromycin-inhibited to total EEA. Since erythromycin-inhibited plus dissolved EEA equaled total EEA, this tentatively suggests that cell-associated EEA in the open oceanic water column is almost exclusively of bacterial origin. The decay constants of dissolved EEA were in the range of 0.002–0.048 h−1 depending on the type of extracellular enzyme, temperature and depth in the water column. Although dissolved EEA can have different origins, the major contribution of Bacteria to cell-associated EEA and the long life-time of dissolved EEA suggest that Bacteria—and not mesophilic Archaea—are essentially the main producers of EEA in the open subtropical Northeast Atlantic down to bathypelagic layers This research was carried out in the frame of the IMBER-endorsed Spanish project CAIBEX (CTM2007-66408-C02-02) “Plan Nacional de I+D” (MEC), coordinated by J.A. Partial support was obtained by a grant of the Earth and Life Science Division of the Dutch Science Foundation (ALW-NWO; ARCHIMEDES project, 835.20.023) and the ESF MOCA project and the Austrian Science Fund (FWF) projects: I486-B09 and P23234-B11 to G.J.H., by the project STORM (CTM2009-09352/MAR) to J.M.G., a predoctoral Fellowship of the ...