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Microbial Ecology

, Volume 36, Issue 1, pp 75–92 | Cite as

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

  • Y.A.  Vetter
  • J.W.  Deming
  • P.A.  Jumars
  • B.B.  Krieger-Brockett

Abstract

Extracellular enzymes are important agents for microbial foraging and material cycling in diverse natural and man-made systems. Their abundance and effects are analyzed empirically on scales much larger than the forager. Here, we use a modelling approach to analyze the potential costs and benefits, to an individual immobile microbe, of freely releasing extracellular enzymes into a fluid-bathed, stable matrix of both inert and food-containing particles. The target environments are marine aggregates and sediments, but the results extend to biofilms, bioreactors, soils, stored foods, teeth, gut contents, and even soft tissues attacked by disease organisms. Model predictions, consistent with macroscopic observations of enzyme activity in laboratory and environmental samples, include: support of significant bacterial growth by cell-free enzymes; preponderance of particle-attached, as opposed to dissolved, cell-free enzymes; solubilization of particulate substrates in excess of resident microbe growth requirements; and constitutive, abundant enzyme release in some environments. Feeding with cell-free enzymes appears to be limited to substrates within a well-defined distance of the enzyme source. Fluxes of dissolved organic material out of pelagic oceanic aggregates and marine sediments, and difficulty detecting dissolved enzymes in such environments, may reflect characteristics of cell-free enzyme foraging and properties of the enzymes. Our calculations further suggest that cell-free enzymes may often be used by microorganisms as the fastest means to search for food.

Keywords

Enzyme Microbe Extracellular Enzyme Enzyme Release Target Environment 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag New York Inc. 1998

Authors and Affiliations

  • Y.A.  Vetter
    • 1
  • J.W.  Deming
    • 1
  • P.A.  Jumars
    • 1
  • B.B.  Krieger-Brockett
    • 2
  1. 1.School of Oceanography, Box 357940, University of Washington, Seattle, WA 98195, USAUS
  2. 2.Department of Chemical Engineering, Box 351750, University of Washington, Seattle, WA 98195, USAUS

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