Differential decomposition of humic acids by marine and estuarine bacterial communities at varying salinities

Rocker, Dagmar; Kisand, Veljo; Scholz‐Böttcher, Barbara M.; Kneib, Thomas; Lemke, Andreas; Rullkötter, Jürgen; Simon, Meinhard

doi:10.1007/s10533-011-9653-4

Cited by 22 publications

(22 citation statements)

References 54 publications

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“…Although humic matter is considered as recalcitrant, it can at least partially be decomposed by bacteria (Hutalle‐Schmelzer et al, ; Rocker et al ., ; Kisand et al ., ). Furthermore, the degradation of humic acids by marine and estuarine bacterial communities seems to be favoured by specific environmental conditions, for example, along a salinity gradient (Rocker et al ., , b; Kisand et al ., ). Consequently, recalcitrance and lability of organic matter are not per se intrinsic chemical characteristics (Schmidt et al ., ), and may only account for specific environmental settings (Bianchi et al ., ).…”

Section: Discussionmentioning

confidence: 99%

“…However, most of the terrigenous (allochthonous) organic carbon is transported into aquatic ecosystems in the form of refractory organic matter (ROM) resulting in a generally higher retention time due to its slow decomposition by aquatic microorganisms (Bianchi, 2011). A major part of this ROM in freshwater ecosystems is represented by humic matter (Rocker et al, 2012a).…”

Section: Introductionmentioning

confidence: 99%

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Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Kolmakova

Gladyshev

Fonvielle

et al. 2018

Environmental Microbiology

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Summary Non‐predatory mortality of zooplankton provides an abundant, yet, little studied source of high quality labile organic matter (LOM) in aquatic ecosystems. Using laboratory microcosms, we followed the decomposition of organic carbon of fresh 13C‐labelled Daphnia carcasses by natural bacterioplankton. The experimental setup comprised blank microcosms, that is, artificial lake water without any organic matter additions (B), and microcosms either amended with natural humic matter (H), fresh Daphnia carcasses (D) or both, that is, humic matter and Daphnia carcasses (HD). Most of the carcass carbon was consumed and respired by the bacterial community within 15 days of incubation. A shift in the bacterial community composition shaped by labile carcass carbon and by humic matter was observed. Nevertheless, we did not observe a quantitative change in humic matter degradation by heterotrophic bacteria in the presence of LOM derived from carcasses. However, carcasses were the main factor driving the bacterial community composition suggesting that the presence of large quantities of dead zooplankton might affect the carbon cycling in aquatic ecosystems. Our results imply that organic matter derived from zooplankton carcasses is efficiently remineralized by a highly specific bacterial community, but does not interfere with the bacterial turnover of more refractory humic matter.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Kolmakova

Gladyshev

Fonvielle

et al. 2018

Environmental Microbiology

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“…and ), attributable to the presence of polyphenols (Riedel et al ., ) and aliphatic substances (van Dongen et al ., ). A large quantity of the DOC leaching from terrigenous soils consists of humic substances, including polyphenols, which are degraded under marine conditions (Kisand et al ., ; Rocker et al ., ). In our study, tDOM addition had a stimulatory effect on BP only in the oligohaline mesocosms, in which the changes in BCC were the smallest (Figs.…”

Section: Discussionmentioning

confidence: 99%

Differential responses of marine, mesohaline and oligohaline bacterial communities to the addition of terrigenous carbon

Herlemann

Manecki

Dittmar

et al. 2017

Environmental Microbiology

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In response to global warming, increasing quantities of tDOM are transported through estuaries from land to the sea. In this study, we investigated microbial responses to increased tDOM concentrations in three salinity regimes (salinity: 32, 7 and 3) characteristic of the Baltic Sea. Mesocosm experiments performed in May and November revealed low (0-6%) dissolved organic carbon (DOC) utilisation. Molecular DOM analyses using ultrahigh-resolution mass spectrometry identified the terrigenous signal in the tDOM manipulation, but the molecular changes in DOM levels over the course of the experiment were subtle. However, tDOM had significant stimulatory effects on bacterial production in the oligohaline mesocosms. The shift in the bacterial community composition was especially prominent in the tDOM-amended marine and mesohaline mesocosms, but not in the oligohaline mesocosms after 7 and 11 days of incubation. These results suggested the inherent ability of oligohaline bacterial communities to adapt to high tDOM concentrations and therefore to use tDOM. The higher rates of bacterial activity and DOC removal in mesocosms containing UV-pretreated tDOM supported the increased bioavailability of photoinduced, modified tDOM. The overall low rates of microbial tDOM utilisation highlights the importance of abiotic factors in determining the distribution and dynamics of tDOM in estuaries.

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“…The analysis of the initial HA media and the outflow of the flowthrough cultures at the end of the experiments by pyrolysis GC-MS, in fact, showed pronounced differences. They included mainly a reduction of aliphatic and partially also of aromatic compounds at the end of the experiment and thus a loss of complexity (Rocker et al, 2012). The continuous change of the bacterial community composition in the course of the experiments, as shown by the variation in number of DGGE bands and DCA, thus appears to be a response to the reduced complexity and concentration of the HA, but presumably also to grazing or viral lysis.…”

Section: Discussionmentioning

confidence: 95%

Composition of humic acid-degrading estuarine and marine bacterial communities

Rocker

Grüner

Dogs

et al. 2012

FEMS Microbiol Ecol

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We examined the bacterial decomposition of humic acids (HA) in two flowthrough culture experiments, one inoculated by marine and one by estuarine bacterial communities. In both experiments, the cultures were fed with HA media of salinities of 28 and 14, close to their ambient and a distinctly different, foreign salinity. HA were decomposed to > 60% of the initial concentration within 70 days, and the foreign salinity yielded the highest decomposition. A detrended correspondence analysis of denaturing gradient gel electrophoresis (DGGE) banding patterns showed that during incubation, the bacterial community composition underwent distinct changes. A phylogenetic analysis of DGGE bands excised and bacteria isolated at the end on HA as the sole carbon source showed that Alphaproteobacteria and Gammaproteobacteria largely dominated the communities in the marine flow-through cultures, whereas Gammaproteobacteria, Actinobacteria and Alphaproteobacteria dominated the estuarine communities. Eleven of 13 isolates obtained from both experiments were able to grow on HA as the sole carbon source, seven on phenol and three, affiliated to the Roseobacter clade, on various aromatic acids. The bacteria retrieved from the flow-through cultures were closely (96-99%) affiliated to organisms capable of degrading humic matter, aromatic and aliphatic compounds and also to other bacteria reported previously from the Wadden Sea and Weser estuary.

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Differential decomposition of humic acids by marine and estuarine bacterial communities at varying salinities

Cited by 22 publications

References 54 publications

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling

Differential responses of marine, mesohaline and oligohaline bacterial communities to the addition of terrigenous carbon

Composition of humic acid-degrading estuarine and marine bacterial communities

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