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Bacterial salt tolerance is unrelated to soil salinity across an arid agroecosystem salinity gradient

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Author

Summary, in English

In arid and semi-arid ecosystems, salinization is a major threat to the productivity of agricultural land. While the influence of other physical and chemical environmental factors on decomposer microorganisms have been intensively studied in soil, the influence of salinity has been less exhaustively assessed. We investigated the influence of soil salinity on soil bacterial communities in soils covering a range of salt levels. We assessed tolerance of the bacterial communities from Libyan agricultural soils forming a salinity gradient to salt (NaCl), by extracting bacterial communities and instantaneously monitoring the concentration–response to added NaCl with the Leucine incorporation technique for bacterial growth. To maximise our ability to detect differences in bacterial salt tolerance between the soils, we also repeated the assessment of bacterial growth tolerance after one month incubation with 1 or 2% added organic matter additions to stimulate microbial growth levels. We could establish clear concentration–response relationships between bacterial growth and soil salinity, demonstrating an accurate assessment of bacterial tolerance. The in situ soil salinity in the studied soils ranged between 0.64 and 2.73 mM Na (electrical conductivities of 0.74–4.12 mS cm−1; cation exchange capacities of 20–37 mmolc kg−1) and the bacterial tolerance indicated by the concentration inhibiting 50% of the bacterial growth (EC50) varied between 30 and 100 mM Na or between electrical conductivities of 3.0 and 10.7 mS cm−1. There was no relationship between in situ soil salinity and the salt tolerance of the soil bacterial communities. Our results suggest that soil salinity was not a decisive factor for bacterial growth, and thus for structuring the decomposer community, in the studied soils.

Publishing year

2011

Language

English

Pages

1881-1887

Publication/Series

Soil Biology & Biochemistry

Volume

43

Issue

9

Document type

Journal article

Publisher

Elsevier

Topic

  • Biological Sciences

Keywords

  • Soil salinity
  • Decomposition
  • Arid soils
  • Salt
  • Tolerance
  • Ecotoxicology
  • Selective pressure
  • Leucine incorporation
  • Bacterial growth
  • Microbial community composition
  • Biomass

Status

Published

Project

  • Interaction between fungi and bacteria in soil
  • Carbon drivers and microbial agents of soil respiration
  • Effect of environmental factors on fungal and bacterial growth in soil
  • Microbial carbon-use efficiency

Research group

  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 0038-0717