A Predictive Model of Bacterial Foraging by Means of Freely Released Extracellular Enzymes

Vetter, Y.A.; Jiang, Deming; Jumars, P. A.; Krieger-Brockett, BB

doi:10.1007/s002489900095

Cited by 213 publications

(199 citation statements)

References 66 publications

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“…We therefore suggest a more parsimonious explanation is that differences in carbon quality between the treatments caused an uncoupling of bacterial catabolic and anabolic processes. Bacteria solubilize and catabolize available substrates at maximal rates, independent of their specific requirements (del Giorgio and Cole, 1998;Vetter et al, 1998). This results in reduced BGE when growth is constrained by factors such as temperature and nutrient supply, rather than organic carbon (energy) (del Giorgio and Cole, 1998).…”

Section: Discussionmentioning

confidence: 99%

Resource quality affects carbon cycling in deep-sea sediments

et al. 2012

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Deep-sea sediments cover B70% of Earth's surface and represent the largest interface between the biological and geological cycles of carbon. Diatoms and zooplankton faecal pellets naturally transport organic material from the upper ocean down to the deep seabed, but how these qualitatively different substrates affect the fate of carbon in this permanently cold environment remains unknown. We added equal quantities of 13 C-labelled diatoms and faecal pellets to a cold water (À0.7 1C) sediment community retrieved from 1080 m in the Faroe-Shetland Channel, Northeast Atlantic, and quantified carbon mineralization and uptake by the resident bacteria and macrofauna over a 6-day period. High-quality, diatom-derived carbon was mineralized 4300% faster than that from low-quality faecal pellets, demonstrating that qualitative differences in organic matter drive major changes in the residence time of carbon at the deep seabed. Benthic bacteria dominated biological carbon processing in our experiments, yet showed no evidence of resource qualitylimited growth; they displayed lower growth efficiencies when respiring diatoms. These effects were consistent in contrasting months. We contend that respiration and growth in the resident sediment microbial communities were substrate and temperature limited, respectively. Our study has important implications for how future changes in the biochemical makeup of exported organic matter will affect the balance between mineralization and sequestration of organic carbon in the largest ecosystem on Earth.

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Section: Discussionmentioning

confidence: 99%

Resource quality affects carbon cycling in deep-sea sediments

et al. 2012

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“…The good correlation of the kinetic rate constants k andk indicates that the kinetics of BSi dissolution is related to the kinetics of OM degradation, rather than to an intrinsic property of the solid BSi phase, as the latter would require a close coupling of BSi and OM in the particle downflux, which is not the case. Further investigations that integrate studies on how BSi and OM are associated within particles (Schrader, 1971;Tande and Slagstad, 1985;Ragueneau et al, 2002), the structure of diatom skeletons (Hecky et al, 1973;Wetherbee et al, 2000;Volcani, 2002), and models on the use and spreading of hydrolytic enzymes by bacteria (Vetter et al, 1998;Rothman and Forney, 2007) are necessary to elucidate the conditions under which bacteria may mediate BSi dissolution, and the low impact of sediment opal contents on its dissolution rate.…”

Section: Kinetics and Reactive Surface Areamentioning

confidence: 99%

Microbial mediation of benthic biogenic silica dissolution

Holstein

Hensen

2009

Geo-Mar Lett

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Pore water profiles from 24 stations in the South Atlantic (located in the Guinea, Angola, Cape, Guyana, and Argentine basins) show good correlations of oxygen and silicon, suggesting microbially mediated dissolution of biogenic silica. We used simple analytical transport and reaction models to show the tight coupling of the reconstructed process kinetics of aerobic respiration and silicon regeneration. A generic transport and reaction model successfully reproduced the majority of Si pore water profiles from aerobic respiration rates, confirming that the dissolution of biogenic silica (BSi) occurs proportionally to O 2 consumption. Possibly limited to well-oxygenated sediments poor in BSi, benthic Si fluxes can be inferred from O 2 uptake with satisfactory accuracy. Compared to aerobic respiration kinetics, the solubility of BSi emerged as a less influential parameter for silicon regeneration. Understanding the role of bacteria for silicon regeneration requires further investigations, some of which are outlined. The proposed aerobic respiration control of benthic silicon cycling is suitable for benthic-pelagic models. The empirical relation of BSi dissolution to aerobic respiration can be used for regionalization assessments and estimates of the silicon budget to increase the understanding of global primary and export production patterns.

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“…Global POC, HM-DOC and LM-DOC pools are subdivided into three fractions each, defined according to turnover time and Redfield ratios, reflecting different inherent qualities, origin and degree of decomposition. Since the use of hydrolytic exoenzymes belongs to the disposal of bacterial foraging strategies, POC hydrolysis is enhanced by aerobic bacteria [52,12]. As only fermentation converts HM-DOC into LM-DOC, the distribution ratio of POC to the DOC-pools may create a fermentation bottleneck for subsequent mineralization processes.…”

Section: A2 Geochemical Reactionsmentioning

confidence: 99%

Sensitivity analysis of nitrogen and carbon cycling in marine sediments

Holstein

Wirtz

2009

Estuarine, Coastal and Shelf Science

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Biogeochemical cycles in coastal sediments encompass numerous interconnected processes and are sensitive to a high number of external forces. Usually a small subset of these factors is considered when developing state-of-the-art models of marine nutrient cycling. This study therefore aims to assess the degree of complexity required in the model to represent the dependency of major biogeochemical fluxes on both intrinsic as well as external factors. For this, a sensitivity analysis (SA) of the generic Integrated Sediment Model (ISM ) was performed comparing two different model setups: 1) a back barrier tidal flat in the German Wadden Sea and; 2) a deep sea site in the Argentine Basin. Both setups were first calibrated to fit pore water profiles of SO 2+ 4 , NH + 4 and CH 4 . We then employed a new type of SA that evaluates parameter impact rather than targeting variable change. General structural stability of the model is demonstrated by similar sensitivity patterns of both setups regarding carbon and nitrogen cycling. Mean temperature, organic carbon bio-availability, bacterial adaptation and sediment texture emerge as the most influential parameters of ubiquitous importance. It appears that in coastal settings, transport and sediment mixing and the composition of suspended particles in the bottom water are especially important. The nitrogen cycle displays a high responsiveness to internal feedback mechanisms as well as interdependencies to carbon and metal cycling, which is statistically reflected by sensitivities to 79 % of all parameters. In contrast, the carbon cycle appears to be mainly controlled by organic matter decay. The SA also pointed to unexpected responses of the sediment system, which are analyzed by further scenario calculations. These, for example, reveal a nonlinear response of nitrification, denitrification and benthic fluxes of NH 4 and NO 3 to changing bioturbation and bioirrigation due to the interactions of different metabolic pathways.

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A Predictive Model of Bacterial Foraging by Means of Freely Released Extracellular Enzymes

Cited by 213 publications

References 66 publications

Resource quality affects carbon cycling in deep-sea sediments

Resource quality affects carbon cycling in deep-sea sediments

Microbial mediation of benthic biogenic silica dissolution

Sensitivity analysis of nitrogen and carbon cycling in marine sediments

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