Biomedical subjects

F Poly

Publications and source records attributed to F Poly.

6 recordsLinked to original sources

PubMed2002

Waste ecocompatibility in storage and reuse scenarios: global methodology and detailed presentation of the impact study on the recipient environments.

In 1995, the ADEME launched a research program called "Waste Ecocompatibility" in order to define a reliable methodology for measuring the impact of waste in storage or reuse scenarios. The French concept of "Ecocompatibility" is defined as the situation where the pollutant flux from waste disposed of or used in specified conditions is compatible with the environmental acceptance of the receiving environments. The chief feature of this definition is to integrate the evaluation of the three following terms: pollutants emission from the waste, transport of the pollutants from the waste to the receptor cells and the environmental acceptance of the receiving environments. The "Waste Ecocompatibility" program consisted of a literature survey and an experimental part. The literature study aimed to determine factors and waste characteristics to be considered for a reliable ecocompatility assessment, to provide an overview of the available tools for measuring those factors and characteristics and to propose a first approach of the methodology. In the framework of the experimental program, this approach was then applied to three theoretical scenarios to validate the laboratory tools (comparative study of laboratory and field results) and to calibrate the global methodology. This paper deals with the results of the experimental program concerning the impact study on receiving environments: impact on plants and microorganisms living in soil, impacts on soil fauna and aquatic fauna. In other papers we intend to present the operational methodology for the assessment of waste ecocompatibility. It includes bio-assays at laboratory scale (microcosms), pilot scale (mesocosms) and in situ experiments (experimental prairie). To limit the use of in situ experiments other research works are necessary to validate bio-assays at laboratory or pilot scale.

Animals↗

PubMed2001

Characterization of bacterial and fungal soil communities by automated ribosomal intergenic spacer analysis fingerprints: biological and methodological variability.

Automated rRNA intergenic spacer analysis (ARISA) was used to characterise bacterial (B-ARISA) and fungal (F-ARISA) communities from different soil types. The 16S-23S intergenic spacer region from the bacterial rRNA operon was amplified from total soil community DNA for B-ARISA. Similarly, the two internal transcribed spacers and the 5.8S rRNA gene (ITS1-5.8S-ITS2) from the fungal rRNA operon were amplified from total soil community DNA for F-ARISA. Universal fluorescence-labeled primers were used for the PCRs, and fragments of between 200 and 1,200 bp were resolved on denaturing polyacrylamide gels by use of an automated sequencer with laser detection. Methodological (DNA extraction and PCR amplification) and biological (inter- and intrasite) variations were evaluated by comparing the number and intensity of peaks (bands) between electrophoregrams (profiles) and by multivariate analysis. Our results showed that ARISA is a high-resolution, highly reproducible technique and is a robust method for discriminating between microbial communities. To evaluate the potential biases in community description provided by ARISA, we also examined databases on length distribution of ribosomal intergenic spacers among bacteria (L. Ranjard, E. Brothier, and S. Nazaret, Appl. Environ. Microbiol. 66:5334-5339, 2000) and fungi.

Bacteria↗

PubMed2001

Comparison of nifH gene pools in soils and soil microenvironments with contrasting properties.

The similarities and differences in the structures of the nifH gene pools of six different soils (Montrond, LCSA-p, Vernon, Dombes, LCSA-c, and Thysse Kaymor) and five soil fractions extracted from LCSA-c were studied. Bacterial DNA was directly extracted from the soils, and a region of the nifH gene was amplified by PCR and analyzed by restriction. Soils were selected on the basis of differences in soil management, plant cover, and major physicochemical properties. Microenvironments differed on the basis of the sizes of the constituent particles and the organic carbon and clay contents. Restriction profiles were subjected to principal-component analysis. We showed that the composition of the diazotrophic communities varied both on a large scale (among soils) and on a microscale (among microenvironments in LCSA-c soil). Soil management seemed to be the major parameter influencing differences in the nifH gene pool structure among soils by controlling inorganic nitrogen content and its variation. However, physicochemical parameters (texture and total C and N contents) were found to correlate with differences among nifH gene pools on a microscale. We hypothesize that the observed nifH genetic structures resulted from the adaptation to fluctuating conditions (cultivated soil, forest soil, coarse fractions) or constant conditions (permanent pasture soil, fine fractions). We attempted to identify a specific band within the profile of the clay fraction by cloning and sequencing it and comparing it with the gene databases. Unexpectedly, the nifH sequences of the dominant bacteria were most similar to sequences of unidentified marine eubacteria.

Bacteria↗

PubMed2000

Monitoring complex bacterial communities using culture-independent molecular techniques: application to soil environment.

Over the last decade, important advances in molecular biology led to the development of culture-independent approaches to describing bacterial communities. These new strategies, based on the analysis of DNA directly extracted from environmental samples, circumvent the steps of isolation and culturing of bacteria, which are known for their selectivity leading to a non-representative view of the extent of bacterial diversity. This review provides an overview of the potentials and limitations of some molecular approaches currently used in microbial ecology. Examples of applications to the study of indigenous soil microbial community illustrate the feasibility and the power of such approaches.

Bacteria↗

PubMed2000

Heterogeneous Cell Density and Genetic Structure of Bacterial Pools Associated with Various Soil Microenvironments as Determined by Enumeration and DNA Fingerprinting Approach (RISA).

The cell density and the genetic structure of bacterial subcommunities (further named pools) present in the various microenvironments of a silt loam soil were investigated. The microenvironments were isolated first using a procedure of soil washes that separated bacteria located outside aggregates (outer part) from those located inside aggregates (inner part). A nondestructive physical fractionation was then applied to the inner part in order to separate bacteria located inside stable aggregates of different size (size fractions, i.e., two macroaggregate fractions, two microaggregate fractions, and the dispersible day fraction). Bacterial densities measured by acridine orange direct counts (AODC) and viable heterotrophic (VH) cell enumerations showed the heterogeneous quantitative distribution of cells in soil. Bacteria were preferentially located in the inner part with 87.6% and 95.4% of the whole AODC and VH bacteria, respectively, and in the microaggregate and dispersible clay fractions of this part with more than 70% and 80% of the whole AODC and VH bacteria, respectively. The rRNA intergenic spacer analysis (RISA) was used to study the genetic structure of the bacterial pools. Different fingerprints and consequently different genetic structures were observed between the unfractionated soil and the microenvironments, and also among the various microenvironments, giving evidence that some populations were specific to a given location in addition to the common populations of all the microenvironments. Cluster and multivariate analysis of RISA profiles showed the weak contribution of the pools located in the macroaggregate fractions to the whole soil community structure, as well as the clear distinction between the pool associated to the macroaggregate fractions and the pools associated to the microaggregate ones. Furthermore, these statistical analyses allowed us to ascertain the influence of the clay and organic matter content of microenvironments on the genetic structure relatedness between pools.

Journal Article↗

PubMedDate not supplied

Improvement in the RFLP procedure for studying the diversity of nifH genes in communities of nitrogen fixers in soil.

Several specific primers for the nifH gene were tested with different pure telluric N2-fixing strains. A PolF/PolR primer set provided successful amplification of 19 representative N2-fixing strains. Three restriction enzymes, HaeIII, NdeII and MnlI, chosen for restriction fragment length polymorphism (RFLP) analyses, were the most discriminating for the study of nifH gene diversity as they resulted in differences between strains at the species level. Amplification by selected primers and RFLP were applied to assess the genetic diversity of the nifH gene pool in soil. Pair soils, one under cultivation, the second under permanent pasture, were found to harbor a contrasting diversity of nifH genes. Pure strain profiles could not be recognized in the nifH soil patterns. Using the simple procedure described, it was shown that the structure of nitrogen fixers in soil was influenced by soil functioning.

Bacteria↗