The Influence of Microbial Community Structure and Function on Community-Level Physiological Profiles

  • Jay L. Garland
  • K. L. Cook
  • C. A. Loader
  • B. A. Hungate

Abstract

Patterns of carbon source utilization, or community-level physiological profiles (CLPP), produced from direct incubation of environmental samples in BIOLOG microplates can consistently discriminate spatial and temporal gradients within microbial communities. While the resolving power of the assay appears significant, the basis for the differences in the patterns of sole carbon source utilization among communities remains unclear. Carbon source utilization as measured in this assay is a measure of functional potential, rather than in situ activity, since enrichment occurs over the course of incubation, which can range from 24 to 72 hours (or even longer) depending on inoculum density. The functional profile of a community could be an indicator of carbon source availability and concomitant selection for specific functional types of organisms. A more limited view of the profile is as a composite descriptor of the microbial community composition without any ecologically relevant functional information. We manipulated microbial community structure and function in laboratory microcosms to evaluate their influence on CLPP. The structure of rhizosphere communities was controlled by inoculating axenic plants (wheat and potato) with different mixed species (non-gnotobiotic) inocula. Inoculum source influenced CLPP more strongly than plant type, indicating that CLPP primarily reflected differences in microbial community structure than function. In order to more specifically examine the influence of microbial function on CLPP, specific carbon sources in the BIOLOG plates (asparagine and acetate) were added to a continuously stirred tank reactor (CSTR) containing a mixed community of microorganisms degrading plant material. Daily additions of these carbon sources at levels up to 50% of the total respired carbon in the bioreactor caused significant changes in overall CLPP, but caused no, or minor, increases in the specific response of these substrates in the plates. These studies indicate that the functional relevance of CLPP should be interpreted with caution.

Keywords

Communities BIOLOG carbon sources rhizosphere bioreactor 

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References

  1. Barber DA (1967) The effects of microorganisms on the absorption of inorganic nutrients by intact plants. J Exp Bot 18:163–169.CrossRefGoogle Scholar
  2. Finger BW, Strayer RF (1994) Development of an intermediate-scale aerobic bioreactor to regenerate nutrients from inedible crop residues. SAE Technical Paper 941501.Google Scholar
  3. Fredickson JK, Balkwill DL, Zachara JM, Li SW, Brockman FJ, Simmons MA (1991) Physiological diversity and distributions of heterotrophic bacteria in deep Cretaceous sediments of the Atlantic coastal plain. Appl Environ Microb 57: 402–411.Google Scholar
  4. Garland JL (1996a) Analytical approaches to the characterization of samples of microbial communities using patterns of potential carbon source utilization. Soil Biol Biochem 28:213–221.CrossRefGoogle Scholar
  5. Garland JL (1996b) Patterns of potential carbon source utilization by rhizosphere communities. Soil Biol Biochem 28:223–230.CrossRefGoogle Scholar
  6. Garland JL, Mills AL (1991) Classification and characterization of heterotrophic microbial communities on the basis of patterns of community-level sole-carbon- source utilization. Appl Envrion Microb 57:2351–2359.Google Scholar
  7. Garland JL, Mills AL (1994). A community-level physiological approach for studying microbial communities, pp. 77–83. In Ritz K, Dighton J, Giller KE (ed.) Beyond the biomass: compositional and functional analysis of soil microbial communities. John Wiley & Sons, Chichester UK.Google Scholar
  8. Haack SK, Garchow H, Klugg MJ, Forney LJ (1995) Analysis of factors affecting the accuracy, reproducibility, and interpretation of microbial community carbon source utilization profiles. Appl Environ Microb 61:1458–1468.Google Scholar
  9. Hobbie JE, Daley RJ, Jasper S (1977) Use of Nucleopore filters for counting bacteria for fluorescent microscopy. Appl Environ Microb 33:1225–1228.Google Scholar
  10. Hussey G, Stacey NJ (1981) In Vitro propagation of potato (Solanun tuberosum L.) Annals Bot 48:787–796Google Scholar
  11. Insam H, Amor K, Renner M, Crepaz C (1996) Changes in functional abilities of the microbial community during composting of manure. Microb Ecol 31:77–87.CrossRefGoogle Scholar
  12. Lehman RM, Colwell FS, Ringelberg DB, White DC (1995) Combined microbial community-level analyses for quality assurance of terrestial subsurface cores. J Microb Meth 22:263–281.CrossRefGoogle Scholar
  13. Morales A, Garland JL, Lim DV (1996) Survival of potentially pathogenic human-associated bacteria in the rhizosphere of hydroponically-grown wheat. FEMS Microbiol Ecol 20:155–162.PubMedCrossRefGoogle Scholar
  14. Murashige T, Skoog F (1962) A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol Plant 15:473–497.CrossRefGoogle Scholar
  15. Winding A (1994) Fingerprinting bacterial soil communities using Biolog microtitre plates, pp. 85–94. In Ritz K, Dighton J, Giller KE (eds.) Beyond the biomass: compositional and functional analysis of soil microbial communities. John Wiley & Sons, Chichester, UK.Google Scholar
  16. Zak JC, Willig MR, Moorehead DL, Wildman HG (1994) Functional diversity of microbial communities: a quantitative approach. Soil Biol Biochem 26:1101–1108.CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Jay L. Garland
    • 1
  • K. L. Cook
    • 1
  • C. A. Loader
    • 1
  • B. A. Hungate
    • 2
  1. 1.Dynamac CorporationKennedy Space CenterUSA
  2. 2.Smithsonian Environmental Research CenterEdgewaterUSA

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