Response of soil bacteria to Hg(II) in relation to soil characteristics and cell location

The response of indigenous bacterial communities to the addition of inorganic mercury (50 micromolar of Hg(II)) was compared over a 30 day period in four soils of contrasting properties. Hg(II) impact was estimated by following population dynamics of viable heterotrophic bacteria (VH) and mercury re...

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Bibliographic Details
Published in:FEMS microbiology ecology 1997-12, Vol.24 (4), p.321-331
Main Authors: Ranjard, L, Richaume, A, Jocteur-Monrozier, L, Nazaret, S
Format: Article
Language:English
Subjects:
Aggregates
Bacteria
Bioavailability
Clay soils
Ecology
Enumeration
Gram‐negative bacteria
Gram‐positive bacteria
Heterotrophic bacteria
Indigenous community
Inner and outer parts
Lag phase
Life Sciences
Mercury
Mercury (metal)
Mercury compounds
Microbiology
Organic matter
Organic soils
Population dynamics
Qualitative analysis
Soil aggregate
Soil aggregates
Soil bacteria
Soil characteristics
Soil microorganisms
Soil organic matter
Soil properties
Soil resistance
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Summary:The response of indigenous bacterial communities to the addition of inorganic mercury (50 micromolar of Hg(II)) was compared over a 30 day period in four soils of contrasting properties. Hg(II) impact was estimated by following population dynamics of viable heterotrophic bacteria (VH) and mercury resistant bacteria (HgR) by indirect enumeration in unfractionated soil and in the inner and outer parts of soil aggregates obtained by successive washings. Numbers of VH bacteria in unfractionated soils were not affected by mercury in any of the studied soils, whereas an increase in resistant bacteria was observed in all of them. The lag phase before the increase of HgR bacteria and the magnitude of the enrichment could be related to soil organic matter and clay contents suggesting that these factors govern mercury bioavailability. In fractionated soil, the increase of resistant populations was more pronounced in the outer part (representing mainly bacteria in macropores) than in the inner part of soil aggregates. This difference in response was clearer in soils with well developed aggregates. Qualitative analysis revealed that exposure to Hg caused a large increase in the proportion of Gram-negative strains among HgR bacteria in both soil parts.
ISSN:0168-6496
1574-6941
DOI:10.1111/j.1574-6941.1997.tb00449.x