AME 56:41-54 (2009)  -  DOI:

Consumption and release of dissolved organic carbon by marine bacteria in a pulsed-substrate environment: from experiments to modelling

M. Eichinger1,3,*, S. A. L. M. Kooijman2, R. Sempéré1, D. Lefèvre1, G. Grégori1, B. Charrière1, J. C. Poggiale1

1Université de la Méditerranée, Laboratoire de Microbiologie Géochimie et Ecologie Marines (LMGEM) CNRS/INSU, UMR 6117, Centre d’Océanologie de Marseille, Campus de Luminy, Case 901, 13 288 Marseille Cedex 9, France
2Vrije Universiteit, Faculty of Earth and Life Science, Department of Theoretical Biology, de Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
3Present address: IFREMER Centre de Brest, Département de Biogéochimie et Ecotoxicologie, BP 70, 29280 Plouzané, France

ABSTRACT: To investigate the effects of episodic occurrence of dissolved organic carbon (DOC) in the natural environment, bacterial degradation of labile DOC was studied under laboratory- controlled conditions followed by modelling. A single labile DOC compound was periodically added to the experimental culture and its degradation by a monospecific marine bacterial strain was followed. The measured variables were DOC and bacterial biomass determined from the particulate organic carbon values. Experimental dynamics showed a repetition of 2 successive patterns after each DOC pulse: (1) substrate consumption and bacterial growth in the first few hours after substrate addition, followed by (2) bacterial reduction (organic carbon-related) and associated non-labile DOC release within the next few hours. Based on these experimental results, the Dynamic Energy Budget theory was applied for the first time to such conditions to develop a mechanistic model that comprised 7 parameters and 4 state variables in which bacterial biomass was fractionated into reserve and structure compartments. The model was constructed by accounting for a constant specific maintenance rate and comprised 2 different cell maintenance fluxes, one fuelled from cell reserves when substrate was abundant and one from reserves and cell structures when starvation occurred. This new model of bacterial degradation adequately matched experimental measurements and accurately reproduced the accumulation of non-labile DOC in the culture during the experiment. This model can easily be implemented in an aquatic biogeochemical model and could provide better understanding of the role of bacteria in carbon cycling in fluctuating environments.

KEY WORDS: Bacterial dynamics · DOC degradation · DOC release · Mechanistic model · DEB theory

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Cite this article as: Eichinger M, Kooijman SALM, Sempéré R, Lefèvre D, Grégori G, Charrière B, Poggiale JC (2009) Consumption and release of dissolved organic carbon by marine bacteria in a pulsed-substrate environment: from experiments to modelling. Aquat Microb Ecol 56:41-54.

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