Consumption and release of dissolved organic carbon by marine bacteria in pulsed-substrate environment: from experiments to modelling
Eichinger, M., Kooijman, S. A. L. M. and Sempéré, R. and Poggiale, J.-C. 2009.
DOC consumption and release by marine bacteria in transient environment: from experiments to modelling.
Aquatic Microbial Ecology 56: 41 - 54
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.