http://www.cnr.it/ontology/cnr/individuo/prodotto/ID53064
Metabolic and bacteria diversità in soils historically contaminated by heavy metals and hydrocarbons. (Articolo in rivista)
- Type
- Label
- Metabolic and bacteria diversità in soils historically contaminated by heavy metals and hydrocarbons. (Articolo in rivista) (literal)
- Anno
- 2008-01-01T00:00:00+01:00 (literal)
- Alternative label
Vivas A.*, Moreno B.*, Del Val C.**, Macci C., Masciandaro G., Benitez E.* (2008)
Metabolic and bacteria diversità in soils historically contaminated by heavy metals and hydrocarbons.
in Journal of environmental monitoring (Print)
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Vivas A.*, Moreno B.*, Del Val C.**, Macci C., Masciandaro G., Benitez E.* (literal)
- Pagina inizio
- Pagina fine
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
- Rivista
- Note
- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- *EEZ, CSIC - Granada (Spagna)
**DECSAI, University of Granada, Granada (Spagna) (literal)
- Titolo
- Metabolic and bacteria diversità in soils historically contaminated by heavy metals and hydrocarbons. (literal)
- Abstract
- Abstract
Background, aim, and scope In this work, the potential for
using olive-mill solid waste as an organic amendment for
biochemical and biological restoration of a trichloroethylenecontaminated
soil, which has previously been stabilized
through vermicomposting processes, has been explored.
Materials and methods Trichloroethylene-contaminated water
was pumped into soil columns with a layer of vermicompost
at 10-cm depth (biobarrier system). The impacts of the trichloroethylene
on the microbial community were evaluated
by determining: (1) the overall microbial activity (estimated
as dehydrogenase activity) and enzyme activities related to
the main nutrient cycles (²-glucosidase, o-diphenoloxidase,
phosphatase, urease, and arylsulphatase activities). In addition,
isoelectric focusing of the soil extracellular humic-²-glucosidase
complexes was performed to study the enzymatically
active humicmatter related to the soil carbon cycle. (2) The soil
bacterial diversity and the molecular mechanisms for the
bacterial resistance to organic solvents were also determined.
For this, polymerase chain reaction (PCR)-denaturing gradient
gel electrophoresis (DGGE) was used to detect changes in
bacterial community structure and PCR-single-strand conformational
polymorphism (SSCP) was developed and optimised
for detection and discrimination of the resistance-nodulationdivision
(RND) genes amplified from the contaminated soils.
Results Vermicompost reduced, with respect to the unamended
soil, about 30%of the trichloroethylene leaching during the
first month of the experiment. Trichloroethylene had a marked
negative effect on soil dehydrogenase, ²-glucosidase, urease,
phosphatase, and arylsulphatase activities. Nevertheless, the
vermicompost tended to avoid this toxic effect. Vermicompost
also displays stable humic-²-glucosidase complexes that
increased the extracellular activity related to C-cycle in the
contaminated soils. The isoelectric focusing technique showed
a more biochemically active humic matter in the soil sampled
under the vermicompost. The behaviour of the three main
phyla of bacteria isolated from the DGGE bands was quite
different. Bands corresponding to Actinobacteria disappeared,
whereas those affiliated with Proteobacteria remained after
the trichloroethylene contamination. The disappeared Actinobacteria
became visible in the soil amended with the vermicompost.
Bands corresponding to Bacteriodetes appeared
only in columns of contaminated soils. In this study, six types
of RND proteins were detected by PCR-SSCP in the natural
soil, three in the trichloroethylene-contaminated soil and 7/5
in trichloroethylene-contaminated soil above/below the vermicompost
in the biobarrier columns. Trichloroethylene
tended to reduce or eliminate all the clones detected in the
uncontaminated soil, whereas new efflux pumps appeared in
the biobarrier columns.
Discussion Although enzymes incorporated into the humic
substances of vermicomposted olive wastes are quite stable,
trichloroethylene also inhibited the background levels of the
soil extracellular ²-glucosidase activity in the amended soils.
The decrease was less severe in the biobarrier system, but in
any case, no relation was found between the levels of trichloroethylene
in soil and extracellular ²-glucosidase activity,
or between the latter and the quantity of humic carbon in soils.The isoelectric focusing technique was carried out in the
humic fraction to determine whether the loss of activity occurred
in overall extracellular ²-glucosidase or in that linked
to stable humic substances (humicenzyme complexes). The
contaminated soils showed the lower enzyme activities,
whereas contaminated and amended soils presented greater
quantity of focalised (and therefore stable) humic carbon and
spectra heterogeneity: very different bands with higher
enzyme activities. No clear relationship between trichloroethylene
concentration in soil and diversity of the bacterial
population was noted. Similar patterns could be found when
the community structures of bacteria and microbial activity
were considered. Since the use of the dehydrogenase assay
has been recognised as a useful indicator of the overall measure
of the intensity of microbial metabolism, these results
could be attributed to PCR-DGGE methodology, since the
method reveals the presence of dominant populations regardless
of their metabolic state. Trichloroethylene maintained or
even increased the number of clones with the DNA encoding
for RND proteins, except for the contaminated soil located
above the vermicompost. However, the main effect of trichloroethylene
was to modify the structure of the community in
contaminated soils, considering the type of efflux pumps
encoded by the DNA extracted from soil bacteria.
Conclusions Trichloroethylene inhibited specific functions in
soil and had a clear influence on the structure of the autochthonous
bacterial community. The organic matter released
by the vermicomposted olive waste tended to avoid the toxic
effect of the contaminant. Trichloroethylene also inhibited the
background levels of the soil extracellular ²-glucosidase
activity, even when vermicompost was present. In this case,
the effect of the vermicompost was to provide and/or to
stimulate the humic-²-glucosidase complexes located in the
soil humic fraction >104, increasing the resistance of the enzyme
to the inhibition. The bacterial community from the
soil presented significantly different mechanisms to resistance
to solvents (RND proteins) under trichloroethylene
conditions. The effect of the vermicompost was to induce
these mechanisms in the autochthonous bacterial community
and/or incorporated new bacterial species, able to grow in a
trichloroethylene-contaminated ambient. Coupled biochemical
and molecular methodologies are therefore helpful
approaches in assessing the effect of an organic amendment
on the biochemical and biological restoration of a trichloroethylene-
contaminated soil.
Recommendations and perspectives Since the main biochemical
and biological effects of the organic amendment on
the contaminated soil seem to be the incorporation of
biochemically active humic matter, as well as new bacterial
species able to grow in a trichloroethylene-contaminated ambient,
isoelectric focusing and PCR-SSCP methodologies
should be considered as parts of an integrated approach to
determine the success of a restoration scheme. (literal)
- Prodotto di
- Autore CNR
Incoming links:
- Autore CNR di
- Prodotto
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#rivistaDi
