Heterotrophic bacteria activity in a turbulent field

Authors

  • Francesc Peters Institut de Ciències del Mar (CSIC)
  • Helena Torné Institut de Ciències del Mar (CSIC)
  • Òscar Guadayol University of Lincoln, Regne Unit.

Keywords:

bacteria, turbulence, diffusivity, production, aggregates.

Abstract

Marine heterotrophic bacteria need dissolved substances for metabolism and growth. The flux of solutes towards microorganisms by molecular diffusion is quite slow. Turbulence, ubiquitous in the ocean, may increase this flux. This effect depends on the diffusivity of the solute and the size of organisms. Bacteria require dissolved organic matter that may be of high molecular weight, that is, low diffusivity, and thus the enhancement owing to turbulence may be larger. After a brief overview of the effects of turbulence on osmotrophic microorganisms, we show the results of bacterial growth experiments under turbulence conditions and with carbon sources of different molecular weight. We see a general trend of larger effects of turbulence with the high molecular weight substrate, albeit the absolute values of the observed effects adjust poorly to expected effects. The formation of aggregates that hydrodynamically may be considered as a particle explain part of this discrepancy but not all.

Keywords: bacteria, turbulence, diffusivity, production, aggregates.

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