Photochemical Production and Behavior of Hydroperoxyacids in Heterotrophic Bacteria Attached to Senescent Phytoplanktonic Cells

Petit, Morgan; Sempéré, Richard; Vaultier, Frédéric; Rontani, J.‐F.

doi:10.3390/ijms140611795

Cited by 8 publications

(13 citation statements)

References 53 publications

(72 reference statements)

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“…3.1. Singlet oxygen transfer efficiency Petit et al (2013) previously showed that the photodegradation state of attached bacteria was well correlated with the degradation of chlorophyll a in phytodetritus. If chlorophyll a constitutes the main inducer of type II photosensitized oxidation in phytodetritus (Nelson, 1993), CDOM, which is produced increasingly during irradiation (Coelho et al, 2011;Cory et al, 2008Cory et al, , 2010Dalrymple et al, 2010) can induce the production of singlet oxygen in the aqueous phase (Sandvik et al, 2000) and thus impact bacteria (Glaeser et al, 2010).…”

Section: Resultsmentioning

confidence: 92%

“…coccoliths) could reduce the lifetime of 1 O 2 and inhibit its migration to bacterial biomass. Indeed, if the transfer of 1 O 2 is strongly favoured between two lipophilic membranes (such as those of phytoplankton and associated bacteria; Petit et al, 2013), this excited form of oxygen might be quickly deactivated if the two membranes are separated by a polar structure. Thus charged mineral surfaces, such as frustules or coccoliths, may allow for enhanced bacterial growth and biodegradation of phytodetritus by inhibition of 1 O 2 transfer.…”

Section: Introductionmentioning

confidence: 99%

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Transfer of singlet oxygen from senescent irradiated phytoplankton cells to attached heterotrophic bacteria: Effect of silica and carbonaceous matrices

et al. 2015

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The effect of silica and carbonaceous matrices (charged mineral surfaces) in phytoplankton cells on the transfer of singlet oxygen from irradiated phytodetritus to their attached bacteria was investigated under controlled laboratory conditions. Our results indicate that a silica matrix (i.e. as in diatom frustules) inhibits the transfer of singlet oxygen and limits the induced photodegradation of cis-vaccenic acid (a fatty acid generally considered as specific to bacteria). In contrast, a carbonaceous matrix (i.e. as in coccoliths) does not seem to inhibit the transfer probably due to the release of coccoliths upon cell death. As a consequence, bacteria associated with phytodetritus from diatoms should be in a healthy state and biodegradation of organic matter associated with these particles should be favoured. These results should contribute to a better understanding of photosensitized degradation processes and to a better estimation of the balance between degradation and preservation of organic material during sedimentation in seawater

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Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Transfer of singlet oxygen from senescent irradiated phytoplankton cells to attached heterotrophic bacteria: Effect of silica and carbonaceous matrices

et al. 2015

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“…1 O 2 is more stable in hydrophobic environments such as membranes (Ogilby, ), and this can facilitate the transfer from one cell to the other if they attach via membranes, for instance. Consistently, senescent (matrix‐less) green algae, as well as coccolithophores, which can shed their coccolith plates during senescence, both transfer 1 O 2 to attached bacteria (Petit et al ., ). Additionally, transfer of 1 O 2 from senescent diatoms is inversely related to silica concentration, and thus extent of frustule formation (Petit et al ., ).…”

Section: Biological Sources Of Extracellular Rosmentioning

confidence: 97%

“…This toxic effect has implications for both free and sinking‐particle associated phytoplankton cells and their associated heterotrophic colonizers. 1 O 2 damages the heterotrophs via oxidation of their lipids ( cis ‐vaccenic acids) (Rontani et al ., ; Petit et al ., ). An open question remains if this results in a strongly asymmetric cellular stress at the point of cell–cell contact, or if 1 O 2 can diffuse within the hydrophobic interior of the cytoplasmic membrane and impact larger regions of the cell envelope.…”

Section: Biological Sources Of Extracellular Rosmentioning

confidence: 97%

The microbial contribution to reactive oxygen species dynamics in marine ecosystems

Zinser

2018

Environ Microbiol Rep

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This review surveys the current state of knowledge of the concentrations, sources and sinks of reactive oxygen species (ROS) in the ocean. Both abiotic and biotic factors contribute to ROS dynamics in seawater, and ROS can feature prominently in marine microbe-microbe interactions. The sun plays a key role in the production of ROS in the ocean, and consequently ROS concentrations are typically maximal in the sun-exposed surface. However, microbes can also contribute significantly to extracellular ROS. Production of superoxide is widespread within the microbial community, and may benefit the producers as antimicrobial agents or perhaps more generally, as a means of nutrient scavenging. Decomposition of hydrogen peroxide is a community-wide activity, though some members may play less significant roles in this process. The more reactive forms of ROS, singlet oxygen and the hydroxyl radical, may be less important as microbial stressors, as they tend to react with the chemicals in seawater before they can contact the cells. However, exceptions may exist for microbes attached to singlet oxygen-generating sinking particulate matter. Extracellular ROS thus plays an important role in the ecology of marine microbes, the full extent to which we are only beginning to appreciate.

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“…While results did not show any specific FA marker of the frustule, 456 frustule-associated FA were characterised by a very low degree of unsaturation with 457 predominance of14:0, 16:0 and 18:0 FA. Although high pH (NaOH 1 mol.l -1 ) and the absence 458 of chlorophyll favour neither autoxidation nor photooxidation (Petit et al, 2013;Rontani, 459 2001), the reactivity of unsaturated FA to oxidation could have led to a decrease of 460 unsaturation degree due to experimental conditions and extraction process. However, tests to 461 determine the effect of temperature (70 °C) on polyunsaturated FA (20:4(n-6)), and previous 462 observations that report unsaturated FA conservation during hot saponification (> 100 °C, see 463 section 2.7.1), suggest that our protocol had little effect on FA unsaturation.…”

Section: Discussionmentioning

confidence: 99%

Fatty acids associated with the frustules of diatoms and their fate during degradation—A case study in Thalassiosira weissflogii

Suroy

Moriceau

Boutorh

et al. 2014

Deep Sea Research Part I: Oceanographic Research Papers

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12Diatoms are major actors in the export of organic carbon out of the euphotic zone. Yet, 13 the processes linking biogenic silica and carbon sedimentation fluxes to deep oceanic layers 14 remain unclear. Analysing organic fractions in biominerals is challenging because efficient 15 cleaning often led to structural alteration of organic molecules. Hence, although lipids are 16 widely used as biogeochemical markers in ocean flux study, few studies have dealt with the 17 lipids that are associated with frustules. In the present study, a protocol was set up to extract 18 and quantify the fatty acids associated to the frustule of the diatom species Thalassiosira 19 weissflogii. The protocol involves solvent extraction of diatom external lipids, followed by 20 clean frustule dissolution by 4% NaOH during 1h at 95°C and subsequent solvent re-21 extraction of frustule-associated lipids. Results confirmed that this protocol was efficient first, 22to isolate the frustule from the rest of the cellular organic carbon and second to extract and 23 quantify fatty acids (FA) associated to frustules of this species. FA composition of the 24 frustules was significantly different from that of the whole cells consisting primarily of 14:0, 25 34 Keywords: Frustule, Diatoms, Organic Carbon, Lipids, Carbon Export 35 36 Frustule isolation 132Pellet samples were resuspended in 40 ml milliQ water and were hot-sonicated at 70 133 °C for 5 min to fragment the cells (Fig. 1). Tubes were subsequently centrifuged at 5400 g for 134 40 min at 4 °C. The supernatants were removed, and this step was repeated once at lower 135

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Photochemical Production and Behavior of Hydroperoxyacids in Heterotrophic Bacteria Attached to Senescent Phytoplanktonic Cells

Cited by 8 publications

References 53 publications

Transfer of singlet oxygen from senescent irradiated phytoplankton cells to attached heterotrophic bacteria: Effect of silica and carbonaceous matrices

Transfer of singlet oxygen from senescent irradiated phytoplankton cells to attached heterotrophic bacteria: Effect of silica and carbonaceous matrices

The microbial contribution to reactive oxygen species dynamics in marine ecosystems

Fatty acids associated with the frustules of diatoms and their fate during degradation—A case study in Thalassiosira weissflogii

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