1
|
Amiraux R, Patricia B, Christopher B, Jean-François R. Use of Stress Signals of Their Attached Bacteria to Monitor Sympagic Algae Preservation in Canadian Arctic Sediments. Microorganisms 2021; 9:microorganisms9122626. [PMID: 34946228 PMCID: PMC8704379 DOI: 10.3390/microorganisms9122626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 12/12/2021] [Accepted: 12/14/2021] [Indexed: 11/28/2022] Open
Abstract
Based on the strong aggregation of sympagic (ice-associated) algae and the high mortality or inactivity of bacteria attached to them, it was previously hypothesized that sympagic algae should be significant contributors to the export of carbon to Arctic sediments. In the present work, the lipid content of 30 sediment samples collected in the Canadian Arctic was investigated to test this hypothesis. The detection of high proportions of trans vaccenic fatty acid (resulting from cis-trans isomerase (CTI) activity of bacteria under hypersaline conditions) and 10S-hydroxyhexadec-8(trans)-enoic acid (resulting from 10S-DOX bacterial detoxification activity in the presence of deleterious free palmitoleic acid) confirmed: (i) the strong contribution of sympagic material to some Arctic sediments, and (ii) the impaired physiological status of its associated bacterial communities. Unlike terrestrial material, sympagic algae that had escaped zooplanktonic grazing appeared relatively preserved from biotic degradation in Arctic sediments. The expected reduction in sea ice cover resulting from global warming should cause a shift in the relative contributions of ice-associated vs. pelagic algae to the seafloor, and thus to a strong modification of the carbon cycle.
Collapse
Affiliation(s)
- Rémi Amiraux
- CNRS/INSU/IRD, Mediterranean Institute of Oceanography (MIO), UM 110, Aix-Marseille University, Université de Toulon, 13288 Marseille, France; (R.A.); (B.P.); (B.C.)
- UMR 6539 Laboratoire des Sciences de l’Environnement Marin, (CNRS, UBO, IRD, Ifremer) Institut, Universitaire Européen de la Mer (IUEM), 29280 Plouzané, France
- Takuvik Joint International Laboratory, Département de Biologie, Laval University (Canada)—CNRS, Université Laval, Québec, QC G1V 0A6, Canada
| | - Bonin Patricia
- CNRS/INSU/IRD, Mediterranean Institute of Oceanography (MIO), UM 110, Aix-Marseille University, Université de Toulon, 13288 Marseille, France; (R.A.); (B.P.); (B.C.)
| | - Burot Christopher
- CNRS/INSU/IRD, Mediterranean Institute of Oceanography (MIO), UM 110, Aix-Marseille University, Université de Toulon, 13288 Marseille, France; (R.A.); (B.P.); (B.C.)
| | - Rontani Jean-François
- CNRS/INSU/IRD, Mediterranean Institute of Oceanography (MIO), UM 110, Aix-Marseille University, Université de Toulon, 13288 Marseille, France; (R.A.); (B.P.); (B.C.)
- Correspondence:
| |
Collapse
|
2
|
Amiraux R, Jeanthon C, Vaultier F, Rontani JF. Paradoxical effects of temperature and solar irradiance on the photodegradation state of killed phytoplankton. J Phycol 2016; 52:475-485. [PMID: 26992328 DOI: 10.1111/jpy.12410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/28/2016] [Indexed: 06/05/2023]
Abstract
The aim of this paper was to study the effects of temperature and irradiance on the photodegradation state of killed phytoplankton cells. For this purpose, killed cells of the diatom Chaetoceros neogracilis RCC2022 were irradiated (photosynthetically active radiation) at 36 and 446 J · s(-1) · m(-2) (for the same cumulative dose of irradiation energy) and at two temperatures (7°C and 17°C). Analyses of specific lipid tracers (fatty acids and sterols) revealed that low temperatures and irradiances increased photooxidative damages of monounsaturated lipids (i.e., palmitoleic acid, cholesterol and campesterol). The high efficiency of type II photosensitized degradation processes was attributed to: (i) the relative preservation of the sensitizer (chlorophyll) at low irradiances allowing a longer production of singlet oxygen and (ii) the slow diffusion rate of singlet oxygen through membranes at low temperatures inducing more damages. Conversely, high temperatures and irradiances induced (i) a rapid degradation of the photosensitizer and a loss of singlet oxygen by diffusion outside the membranes (limiting type II photosensitized oxidation), and (ii) intense autoxidation processes degrading unsaturated cell lipids and oxidation products used as photodegradation tracers. Our results may explain the paradoxical relationship observed in situ between latitude and photodegradation state of phytoplankton cells.
Collapse
Affiliation(s)
- Rémi Amiraux
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, Marseille, 13288, France
| | - Christian Jeanthon
- CNRS, UMR 7144, Marine Phototrophic Prokaryotes Team, Station Biologique de Roscoff, Roscoff, 29680, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7144, Oceanic Plankton Group, Station Biologique de Roscoff, Roscoff, 29680, France
| | - Frédéric Vaultier
- Aix-Marseille University, Mediterranean Institute of Oceanography (MIO), Marseille Cedex 9, 13288, France
- CNRS-INSU/IRD UM 110, Université du Sud Toulon-Var, La Garde, 83957, France
| | - Jean-François Rontani
- Aix-Marseille University, Mediterranean Institute of Oceanography (MIO), Marseille Cedex 9, 13288, France
- CNRS-INSU/IRD UM 110, Université du Sud Toulon-Var, La Garde, 83957, France
| |
Collapse
|