Biological oxidation of hydrogen in soils flushed with a mixture of H2, CO2, O2 and N2

A stainless steel cylinder filled with soil was flushed upstream with a H2/CO2/air mixture. The consequence was a strong enrichment of the aerobic, autotrophic hydrogen-oxidising microflora, which reached densities enabling them to oxidize 84.5 ml H2· dm−2· h−1 in the first 25-cm layer. H2 concentration profiles, hydrogen uptake activity and cell numbers correlated well with each other. Most of the organisms isolated were dinitrogen fixers. Thus, soils containing hydrogen-oxidising bacteria may act as a biological shield between H2-rich environments and air, and may be utilized as biofilters, e.g., in the waste-processing industr

Thermophilic bacterial communities in hot composts as revealed by most probable number counts and molecular (16S rDNA) methods

Thermogenic composts are known to host a variety of thermophilic micro-organisms that were recently investigated by cultural means and identified as Thermus thermophilus, Bacillus spp., and Hydrogenobacter spp. In this paper, we present a classical, cultural enumeration of thermophilic populations on the one hand, and a molecular investigation of the bacterial community by restriction enzyme analyses of a clone library of bacterial 16S rRNA genes on the other hand. Bacterial diversity, revealed by the clone analyses of four samples, was shown to undergo a dramatic change between the young (13-18-day) and the old (39-41-day) samples, possibly linked to the general decrease in temperature and the physicochemical evolution of organic matter during the composting process. Among the 200 clones investigated, 69 clones could be identified as Thermus thermophilus and thermophilic Bacillus spp. These results proved both taxa to be among the dominant bacterial populations at the highest temperatures reached by thermogenic compost

Secretion activity of white lupin's cluster roots influences bacterial abundance, function and community structure

White lupin (Lupinus albus L. cv. Amiga) reacts to phosphate deficiency by producing cluster roots which exude large amounts of organic acids. The detailed knowledge of the excretion physiology of the different root parts makes it a good model plant to study plant-bacteria interaction. Since the effect of the organic acid exudation by cluster roots on the rhizosphere microflora is still poorly understood, we investigated the abundance, diversity and functions of bacteria associated with the cluster roots of white lupin, with special emphasis on the influence of root proximity (comparing root, rhizosphere soil and bulk soil fractions) and cluster root growth stages, which are characterized by different excretion activities. Plants were grown for five weeks in microcosms, in the presence of low phosphate concentrations, on acidic sand inoculated with a soil suspension from a lupin field. Plate counts showed that bacterial abundance decreased at the stage where the cluster root excretes high amounts of citrate and protons. In vitro tests on isolates showed that the frequencies of auxin producers were highest in juvenile and mature cluster roots and significantly decreased in senescent cluster roots. However, no significant difference in the frequency of auxin producers was found between cluster and non cluster roots. The diversity and structure of bacterial communities were investigated by DGGE of 16S rDNA and 16S rRNA. The diversity and community structure were mostly influenced by root proximity and, to a lesser extent, by cluster root stage. The richness of bacterial communities decreased with root proximity, whereas the proportion of active populations increased. The high citrate and proton excretion occurring at the mature stage of cluster roots had a strong impact on the structure and richness of the bacterial communities, both in the root and in the rhizosphere soi

WebGIS as boundary tools between scientific geoinformation and disaster risk reduction action in volcanic areas

As the amount of spatial data is growing, there is increased interest in developing tools to explore, visualize and interpret them, with the final aim of informing decision making efficiently. Within the European MIAVITA project, we examined this issue in the case of volcanic areas, where existing geospatial databases are particularly complex due to the number of threats to be considered, including volcanic (e.g. lava flows, ash fall) and non-volcanic hazards, such as landslides or tsunamis. We involved a group of hazard and risk analysts and managers, civil security officers, GIS analysts and system developers to design a Web-based geographical information system (WebGIS). We tested the system at the Mount Cameroon volcano, taking advantage of a complex hazard and risk geographical database. This study enabled identifying key requirements for such tools in volcanic areas, such as the need to manage user privileges differently according to their profile and the status of the volcano. This work also highlights that, in addition to the development of large geoinformation clearinghouses, there is a need for site-specific information systems focused on working procedures of users, in order to fill the last gap between data producers and users

Ecological determinants of fungal diversity on dead wood in European forests

International audienceThe fine-scale ecological determinants for wood-inhabiting aphyllophoroid basidiomycetes were investigated with statistical analyses of the occurrence of fruit bodies on woody debris collected in Switzerland and Ukraine. Three substrate descriptors were considered: diameter, degree of decomposition and host tree species. By means of Multiple Regression Trees, thresholds in the response of fungal communities to these local environmental descriptors were detected. Three classes for diameter, as well as for degree of decomposition were thus delimited. They revealed the importance of very small sizes, which were not reported in the literature so far: the relevant diameter class limits were about 0.72 cm and 1.35 cm. Within the host tree species, a clear distinction between coniferous and broadleaf species was found. The next splits followed rather climatic determinants of tree distribution than taxonomical entities such as families or genera. The fidelity of the 59 fungal species to diameter classes, decomposition classes and host tree species was measured by the Dufrêne-Legendre index and only significant responses after permutation tests were retained. This brought new insights on the ecology of many wood-inhabiting aphyllophoroid basidiomycetes. Redundancy Analysis was applied to investigate the response of fungal species to diameter and degree of decomposition of woody debris from the most common host tree species, Fagus sylvatica. This direct gradient analysis made it possible to reconstruct the succession of fungal species along the wood decomposition process

Frequency and Diversity of Nitrate Reductase Genes among Nitrate-Dissimilating Pseudomonas in the Rhizosphere of Perennial Grasses Grown in Field Conditions

A total of 1246 Pseudomonas strains were isolated from the rhizosphere of two perennial grasses (Lolium perenne and Molinia coerulea) with different nitrogen requirements. The plants were grown in their native soil under ambient and elevated atmospheric CO2 content (pCO2) at the Swiss FACE (Free Air CO2 Enrichment) facility. Root-, rhizosphere-, and non-rhizospheric soil-associated strains were characterized in terms of their ability to reduce nitrate during an in vitro assay and with respect to the genes encoding the membrane-bound (named NAR) and periplasmic (NAP) nitrate reductases so far described in the genus Pseudomonas. The diversity of corresponding genes was assessed by PCR-RFLP on narG and napA genes, which encode the catalytic subunit of nitrate reductases. The frequency of nitrate-dissimilating strains decreased with root proximity for both plants and was enhanced under elevated pCO2 in the rhizosphere of L. perenne. NAR (54% of strains) as well as NAP (49%) forms were present in nitrate-reducing strains, 15.5% of the 439 strains tested harbouring both genes. The relative proportions of narG and napA detected in Pseudomonas strains were different according to root proximity and for both pCO2 treatments: the NAR form was more abundant close to the root surface and for plants grown under elevated pCO2. Putative denitrifiers harbored mainly the membrane-bound (NAR) form of nitrate reductase. Finally, both narG and napA sequences displayed a high level of diversity. Anyway, this diversity was correlated neither with the root proximity nor with the pCO2 treatmen

Secretion activity of white lupin's cluster roots influences bacterial abundance, function and community structure

White lupin (Lupinus albus L. cv. Amiga) reacts to phosphate deficiency by producing cluster roots which exude large amounts of organic acids. The detailed knowledge of the excretion physiology of the different root parts makes it a good model plant to study plant-bacteria interaction. Since the effect of the organic acid exudation by cluster roots on the rhizosphere microflora is still poorly understood, we investigated the abundance, diversity and functions of bacteria associated with the cluster roots of white lupin, with special emphasis on the influence of root proximity (comparing root, rhizosphere soil and bulk soil fractions) and cluster root growth stages, which are characterized by different excretion activities. Plants were grown for five weeks in microcosms, in the presence of low phosphate concentrations, on acidic sand inoculated with a soil suspension from a lupin field. Plate counts showed that bacterial abundance decreased at the stage where the cluster root excretes high amounts of citrate and protons. In vitro tests on isolates showed that the frequencies of auxin producers were highest in juvenile and mature cluster roots and significantly decreased in senescent cluster roots. However, no significant difference in the frequency of auxin producers was found between cluster and non cluster roots. The diversity and structure of bacterial communities were investigated by DGGE of 16S rDNA and 16S rRNA. The diversity and community structure were mostly influenced by root proximity and, to a lesser extent, by cluster root stage. The richness of bacterial communities decreased with root proximity, whereas the proportion of active populations increased. The high citrate and proton excretion occurring at the mature stage of cluster roots had a strong impact on the structure and richness of the bacterial communities, both in the root and in the rhizosphere soi

Examination of Gould's modified S1 (mS1) selective medium and Angle's non-selective medium for describing the diversity of Pseudomonas spp. in soil and root environments

Studies on the diversity of environmental culturable Pseudomonas populations are dependent on the isolation procedure. This procedure includes the use of selective media which may influence the recovery of strains and thus the diversity described. In this study, we assessed the use of two agar isolation media for describing the diversity of soil- and root-inhabiting Pseudomonas associated with the perennial grass Molinia coerulea. A total of 382 Pseudomonas strains were recovered on either non-selective Angle's medium, or on Gould's modified S1 (mS1) Pseudomonas-selective medium. Their diversity was assessed by restriction analysis of PCR (polymerase chain reaction)-amplified 16S-23S rDNA internal transcript spacer sequences. The comparison of mS1- and Angle-recovered populations showed that the use of mS1 selective medium led to an underestimation of both Pseudomonas counts and diversity, especially in the soil environmen

How elevated pCO2 modifies total and metabolically active bacterial communities in the rhizosphere of two perennial grasses grown under field conditions

The response of total (DNA-based analysis) and active (RNA-based analysis) bacterial communities to a pCO2 increase under field conditions was assessed using two perennial grasses: the nitrophilic Lolium perenne and the oligonitrophilic Molinia coerulea. PCR- and reverse transcriptase-PCR denaturing gradient gel electrophoresis analysis of 16S rRNA genes generated contrasting profiles. The pCO2 increase influenced mainly the active and root-associated component of the bacterial community. Bacterial groups responsive to the pCO2 increase were identified by sequencing of corresponding denaturing gradient gel electrophoresis bands. About 50% of retrieved sequences were affiliated to Proteobacteria. Our data suggest that Actinobacteria in soil and Myxococcales (Deltaproteobacteria) in root are stimulated under elevated pCO

Morphic Echoes: Dream Telepathy in Psychoanalysis. An Explanatory Hypothesis

Emerging out of an era in which the ‘paranormal’ was viewed with skepticism by most and asquackery by the scientific community, Freud steered psycho-analysis clear of any association with telepathy or thought transference - phenomena which, however, were reported with some frequency within its domain of inquiry.Although he began by rejecting the whole subject, over the years and through personal experiences, he wrote several papers advocating that psychoanalysts embark on a serious inquiry of this phenomenon, approaching it as a normal rather than paranormal aspect of unconscious functioning.Yet despite the legitimization of psi phenomena through government sponsored research and the Princeton (PEAR) studies, psychoanalysis remained at odds with a phenomenon that appears most commonly and quite dramatically in Dreams. Insecurities about the “scientific” merits of our ‘talking cure’ pushed the subject underground, with only occasional papers emerging every few years which present evidence of telepathic material, but without offering major new theoretical insights.This paper, instigated by personal experience in my practice, searches for the operative roots of dream telepathy as a normal, deeply non-conscious resonance phenomenon, through broad interdisciplinary readings in quantum physics; the Holographic Paradigm; current neuroscience and paleoneurology; Prehistoric Art; developmental studies; psychoanalytic dream theory and group processes; literature on psi from the early 20’s, and our own psychoanalytic literature. From within the framework of a revision of Freud’s first topographical model viewed as a continuum from biological to semiotically mediated organizations of experience and modes of communication (Aragno 1997, 2008), the inquiry takes us to our distant evolutionary past when evidence of ‘representation’ first appeared, leaving traces of early hominid mental capacities. With support from contemporary neurobiology and a broad interdisciplinary base, relevant data is selected and synthesized, like pieces of a puzzle, drawing from this a comprehensive hypothesis for the roots of dream telepathy. The subject is approached from the perspective of a biosemiotic model of human interactions (Aragno, 2008) in which all unconscious communicative processes are viewed as natural rather than supernatural phenomena