Phosphate availability modulates the weathering effectiveness and molecular response of Caballeronia mineralivorans PML1(12).

Backgrounds: Minerals and rocks are important reservoirs of nutrients for the soil biota because of their nutritive contents of P, K or Mg. In nutrient-poor environments such as forest soils, microorganisms capable of mobilizing these nutrients gain an ecological advantage. Acidification-based mineral weathering is one of the mechanisms used by these bacteria, but the molecular players involved and their regulation remain poorly characterized.

Acidification-based mineral weathering mechanism involves a glucose/methanol/choline oxidoreductase in PML1(12).

Unlabelled: While mineral weathering (MWe) plays a key role in plant growth promotion and soil fertility, the molecular mechanisms and the genes used by bacteria to weather minerals remain poorly characterized. Acidification-based dissolution is considered the primary mechanism used by bacteria. This mechanism is historically associated with the conversion of glucose to protons and gluconic acid through the action of particular glucose dehydrogenases (GDH) dependent on the pyrroquinoline quinone (PQQ) cofactor.

The non-ribosomal peptide synthetase-independent siderophore (NIS) rhizobactin produced by PML1(12) confers the ability to weather minerals.

To mobilize nutrients entrapped into minerals and rocks, heterotrophic bacteria living in nutrient-poor environments have developed different mechanisms based mainly on acidolysis and chelation. However, the genetic bases of these mechanisms remain unidentified. To fill this gap, we considered the model strain PML1(12) known to be effective at weathering.

Recent progress in understanding the ecology and molecular genetics of soil mineral weathering bacteria.

Mineral weathering bacteria play essential roles in nutrient cycling and plant nutrition. However, we are far from having a comprehensive view of the factors regulating their distribution and the molecular mechanisms involved. In this review, we highlight the extrinsic factors (i.

The mineral weathering ability of Collimonas pratensis PMB3(1) involves a Malleobactin-mediated iron acquisition system.

Mineral weathering by microorganisms is considered to occur through a succession of mechanisms based on acidification and chelation. While the role of acidification is established, the role of siderophores is difficult to disentangle from the effect of the acidification. We took advantage of the ability of strain Collimonas pratensis PMB3(1) to weather minerals but not to acidify depending on the carbon source to address the role of siderophores in mineral weathering.

Draft Genome Sequence of Collimonas pratensis Strain PMB3(1), an Effective Mineral-Weathering and Chitin-Hydrolyzing Bacterial Strain.

We announce the draft genome sequence of PMB3(1), isolated from the mycorrhizosphere. In addition to its mineral-weathering effectiveness and antifungal activity, this strain is characterized by genomic features that give it great potential as a biocontrol and plant growth-promoting agent in nutrient-poor soils.

Dual transcriptomics and proteomics analyses of the early stage of interaction between Caballeronia mineralivorans PML1(12) and mineral.

Minerals and rocks represent essential reservoirs of nutritive elements for the long-lasting functioning of forest ecosystems developed on nutrient-poor soils. While the presence of effective mineral weathering bacteria was evidenced in the rhizosphere of different plants, the molecular mechanisms involved remain uncharacterized. To fill this gap, we combined transcriptomic, proteomics, geo-chemical and physiological analyses to decipher the potential molecular mechanisms explaining the mineral weathering effectiveness of strain PML1(12) of Caballeronia mineralivorans.

Boron Dissolved and Particulate Atmospheric Inputs to a Forest Ecosystem (Northeastern France).

Boron concentrations and isotopic compositions of atmospheric dust and dissolved depositions were monitored over a two-year period (2012-2013) in the forest ecosystem of Montiers (Northeastern France). This time series allows the determination of the boron atmospheric inputs to this forest ecosystem and contributes to refine our understanding of the sources and processes that control the boron atmospheric cycle. Mean annual dust and dissolved boron atmospheric depositions are comparable in size (13 g·ha·yr and 16 g·ha·yr, respectively), which however show significant intra- and interannual variations.

Metal Immobilization on Wood-Derived Biochars: Distribution and Reactivity of Carbonate Phases.

Metals can be immobilized on biochars by precipitation with carbonate. The distribution of metal-carbonate phases at the surface of biochars and the conditions of their formation, however, are unknown. Electron microscopy and X-photon spectroscopy were used to characterize carbonate phases in various morphological groups of particles of a wood-derived biochar, both before and after a metal-sorption experiment.

The Mineralosphere Concept: Mineralogical Control of the Distribution and Function of Mineral-associated Bacterial Communities.

Soil is composed of a mosaic of different rocks and minerals, usually considered as an inert substrata for microbial colonization. However, recent findings suggest that minerals, in soils and elsewhere, favour the development of specific microbial communities according to their mineralogy, nutritive content, and weatherability. Based upon recent studies, we highlight how bacterial communities are distributed on the surface of, and in close proximity to, minerals.

Atmospheric particulate deposition in temperate deciduous forest ecosystems: interactions with the canopy and nutrient inputs in two beech stands of Northeastern France.

As wood harvests are expected to increase to satisfy the need for bio-energy in Europe, quantifying atmospheric nutrient inputs in forest ecosystems is essential for forest management. Current atmospheric measurements only take into account the <0.45 μm fraction and dry deposition is generally modeled.

Taxonomic and functional diversity of Streptomyces in a forest soil.

In this work we report the isolation and the characterization of 79 Streptomyces isolates from a French forest soil. The 16S rRNA gene phylogeny indicated that a great diversity of Streptomyces was present in this soil, with at least nine different and potentially new species. Growth plate assays showed that most Streptomyces lineages exhibit cellulolytic and hemicellulolytic capacities and potentially participate in wood decomposition.

Chrysotile dissolution in the rhizosphere of the nickel hyperaccumulator Leptoplax emarginata.

Ni phytoextraction processes need further understanding of the interactions between Ni availability in soils and its absorption by plant roots. The large metal uptake and root exudation by hyperaccumulator species could accelerate the weathering process of Ni-bearing phases in the rhizosphere. The aim of this work was to quantify the weathering of a Ni-bearing mineral phase in the rhizosphere of the Ni-hyperaccumulator Leptoplax emarginata.

Biotic and abiotic experimental identification of bacterial influence on calcium isotopic signatures.

In this study, we tested experimentally the influence of plant and bacterial activities on the calcium (Ca) isotope distribution between soil solutions and plant organs. Abiotic apatite weathering experiments were performed under two different pH conditions using mineral and organic acids. Biotic experiments were performed using either apatite or Ca-enriched biotite substrates in the presence of Scots pines, inoculated or not with the rhizosphere bacterial strain Bulkholderia glathei PML1(12), or the B.

Bacterial weathering and its contribution to nutrient cycling in temperate forest ecosystems.

Unlike farmland, forests growing on acidic soils are among the terrestrial ecosystems that are the least influenced or amended by man. Forests which developed on acidic soils are characterized by an important stock of inorganic nutrients entrapped in poorly weatherable soil minerals. In this context, the mineral-weathering process is of great importance, since such minerals are not easily accessible to tree roots.

Influence of forest trees on the distribution of mineral weathering-associated bacterial communities of the Scleroderma citrinum mycorrhizosphere.

In acidic forest soils, availability of inorganic nutrients is a tree-growth-limiting factor. A hypothesis to explain sustainable forest development proposes that tree roots select soil microbes involved in central biogeochemical processes, such as mineral weathering, that may contribute to nutrient mobilization and tree nutrition. Here we showed, by combining soil analyses with cultivation-dependent analyses of the culturable bacterial communities associated with the widespread mycorrhizal fungus Scleroderma citrinum, a significant enrichment of bacterial isolates with efficient mineral weathering potentials around the oak and beech mycorrhizal roots compared to bulk soil.

Mineral weathering by bacteria: ecology, actors and mechanisms.

Soil microbes play an essential role in the environment by contributing to the release of key nutrients from primary minerals that are required not only for their own nutrition but also for that of plants. Although the role of fungi in mineral weathering is beginning to be elucidated, the relative impact of bacteria in this process and the molecular mechanisms involved remain poorly understood. Here, we discuss the ecological relevance of bacterial weathering, mainly in the soil and especially in acidic forest ecosystems, which strongly depend on mineral weathering for their sustainability.

Impact of ectomycorrhizosphere on the functional diversity of soil bacterial and fungal communities from a forest stand in relation to nutrient mobilization processes.

The ectomycorrhizal symbiosis alters the physicochemical and biological conditions in the surrounding soil, thus creating a particular environment called ectomycorrhizosphere, which selects microbial communities suspected to play a role in gross production and nutrient cycling. To assess the ectomycorrhizosphere effect on the structure of microbial communities potentially involved in the mobilization of nutrients from the soil minerals in a poor-nutrient environment, we compared the functional diversity of soil and ectomycorrhizosphere bacterial communities in a forest stand. Two hundred and sixty-four bacterial strains and 107 fungal strains were isolated from the bulk soil of an oak (Quercus petraea) stand and from oak-Scleroderma citrinum ectomycorrhizosphere and ectomycorrhizae, in two soil organo-mineral horizons (0 to 3 cm and 5 to 10 cm).

Root-associated bacteria contribute to mineral weathering and to mineral nutrition in trees: a budgeting analysis.

The principal nutrient source for forest trees derives from the weathering of soil minerals which results from water circulation and from plant and microbial activity. The main objectives of this work were to quantify the respective effects of plant- and root-associated bacteria on mineral weathering and their consequences on tree seedling growth and nutrition. That is why we carried out two column experiments with a quartz-biotite substrate.