Bacterial Stress and Mortality may be a Source of Cell-free Enzymatic Activity in the Marine Environment

Author(s)
Federico Baltar, Daniele De Corte, Taichi Yokokawa
Abstract

Marine microbes play a central role in driving biogeochemical cycles. Microbial extracellular enzymatic activities (EEA) are the 'gatekeeper' of the marine carbon cycle, and these enzymes may be found attached to cells or dissolved (cell-free). Recent studies indicated that the proportion of dissolved enzymatic activity is generally similar to (if not higher than) cell-attached activity. Thus, it is critical to understand the sources and sinks of cell-free EEA in the ocean. We herein empirically tested whether bacterial stress and mortality (induced by mitomycin C) are a source of the cell-free EEA of alkaline phosphatase (APase), beta-glucosidase (BGase), and leucine aminopeptidase (LAPase). We found that bacterial stress and mortality caused relative increases in the proportion of dissolved relative to total EEA of up to 10.5% for APase, 13.5% for BGase, and 7.3% for LAPase. These relative increases in dissolved EEA corresponded to absolute increases in the cell-free pool of 4.8, 7.2, and 3.8% for APase, BGase and LAPase, respectively. Collectively, our results contribute relevant information on the origin of free dissolved extracellular enzymes in marine waters, indicating that bacterial stress and mortality are a source of cell-free enzymatic activity and suggesting a potential link between microbial interactions and the degradation of organic matter via the release of cell-free enzymes.

Organisation(s)
Department of Limnology and Bio-Oceanography
Journal
Microbes and environments
Volume
34
Pages
83-88
ISSN
1342-6311
DOI
https://doi.org/10.1264/jsme2.ME18123
Publication date
2019
Publication status
Published
Peer reviewed
Yes
Austrian Fields of Science 2012
106021 Marine biology
Portal url
https://ucris.univie.ac.at/portal/en/publications/bacterial-stress-and-mortality-may-be-a-source-of-cellfree-enzymatic-activity-in-the-marine-environment(1f843d0d-92ad-4bb9-abff-0e6d0af0bb56).html