Thierry Heulin

• PhD
• Research Director at French National Centre for Scientific Research

Ramlibacter tataouinensis , the type species of the genus Ramlibacter , is renowned for its ability to thrive in hot, arid and nutrient‐poor desert soils. To investigate whether its adaptive properties are shared across all 20 currently described Ramlibacter species found in diverse terrestrial and aquatic habitats worldwide, we conducted a compreh...

We determined the concentrations of trace elements including Fe, Al, rare earth elements and Y (REY), in Ascophyllum nodosum, one of the most abundant brown macroalgae in the North Atlantic. Samples were collected in the Bay of Brest (Brittany, France) and in the estuary of its main contributing river. The Y/Ho, Al/Ga, and Zr/Hf ratios display valu...

The rhizosheath, a cohesive soil layer firmly adhering to plant roots, plays a vital role in facilitating water and mineral uptake. Using genome wide association (GWAS) combined with bulk segregant analysis and gene expression studies in pearl millet, rhizosheath formation was shown to be under complex genetic control in pearl millet and suggests t...

The rhizosheath, a cohesive soil layer firmly adhering to plant roots, plays a vital role in facilitating water and mineral uptake. In pearl millet, rhizosheath formation is genetically controlled and influenced by root exudates. Here, we investigated the impact of root exudates on the microbiota composition, interactions, and assembly processes, a...

Background The rhizosheath, a cohesive soil layer firmly adhering to plant roots, plays a vital role in facilitating water and mineral uptake. In pearl millet, rhizosheath formation is genetically controlled and influenced by root exudates. Here, we investigated the impact of root exudates on the microbiota composition, interactions, and assembly p...

Over the last 30 years, the description of microbial diversity has been mainly based on culture-independent approaches (metabarcoding and metagenomics) allowing an in-depth analysis of microbial diversity that no other approach allows. Bearing in mind that culture-dependent approaches cannot replace culture-independent approaches, we have improved...

The western corn rootworm (WCR) Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) remains one of the economically most important pests of maize (Zea mays) due to its adaptive capabilities to pest management options. This includes the ability to develop resistance to some of the commercial pesticidal proteins originating from different stra...

The current study examines the desiccation-resistant Ramlibacter tataouinensis TTB310T as a model organism for the production of novel exopolysaccharides and their structural features. This bacterium is able to produce dividing forms of cysts which synthesize cell-bound exopolysaccharide. Initial experiments were conducted on the enrichment of cyst...

The rhizosphere, meaning the soil volume influenced by the living roots, hosts several important ecological processes implicating the soil, the root system and active microbiota. These various interactions often impact soil carbon (C) content and nutrient dynamics, as well as soil water retention, by modifying its biological and physico-chemical pr...

Hypersaline ecosystems host a particular microbiota, which can be specifically recruited by halophytes. In order to broaden our knowledge of hypersaline ecosystems, an in natura study was conducted on the microbiota associated with the halophyte Halocnemum strobilaceum from alkaline-saline arid soil in Algeria. We collected and identified a total o...

The rhizosheath, the layer of soil that adheres strongly to roots, influences water and nutrients acquisition. Pearl millet is a cereal crop that plays a major role for food security in arid regions of sub-Saharan Africa and India. We previously showed that root-adhering soil mass is a heritable trait in pearl millet and that it correlates with cha...

Pseudomonads play crucial roles in plant growth promotion and control of plant diseases. However, under natural conditions, other microorganisms competing for the same nutrient resources in the rhizosphere may exert negative control over their phytobeneficial characteristics. We assessed the expression of phytobeneficial genes involved in biocontro...

Rhizosheath size varies significantly with crop genotype, and root exudation is one among its driving factors. Unravelling the relationships between rhizosheath formation, root exudation and soil carbon dynamics may bring interesting perspectives in terms of crop breeding towards sustainable agriculture. Here we grew four pearl millet (C4 plant typ...

Among abiotic stresses, drought is considered the most important growth-limiting factor, particularly in arid and semiarid regions. Therefore, new management strategies are needed to resolve and mitigate these negative consequences, improve soil quality and plant growth, and rationalize water use. In this context, we investigated the role of benefi...

The rhizosheath, the layer of soil that adheres strongly to roots, influences water and nutrients acquisition. Pearl millet is a cereal crop that plays a major role for food security in arid regions of sub Saharan Africa and India. We previously showed that root-adhering soil mass is a heritable trait in pearl millet and that it correlates with cha...

Plants and their associated microbiota have long interacted, forming an assemblage of species oftenreferred to as a holobiont. Microbiomes can greatly expand the genomic and metabolic capabilities oftheir plant hosts, providing or facilitating a range of essential life-supporting functions, including nutri-ent acquisition, immune modulation, growth...

Rhizosheath size varies significantly with crop genotype, and root exudation is one among its driving factors. Unravelling the relationships between rhizosheath formation, root exudation and soil carbon dynamics may bring interesting perspectives in terms of crop breeding towards sustainable agriculture. Here we grew four pearl millet (C4 plant typ...

Aims: The interactions between plant roots and the associated microbiota impact soil aggregation, water retention and plant nutrient availability. Thus, selection of plant genotypes that promote microbial species involved in root-adhering soil aggregation and rhizosheath formation could help improve yield sustainably. Here, we tested pearl millet g...

With the increasing demand for alternative solutions to replace or optimize the use of synthetic fertilizers and pesticides, the inoculation of bacteria that can contribute to the growth and health of plants (PGPR) is essential. The properties classically sought in PGPR are the production of phytohormones and other growth-promoting molecules, and m...

Two-component systems (TCSs) are ubiquitous signaling pathways, typically comprising a sensory histidine kinase (HK) and a response regulator, which communicate via intermolecular kinase-to-receiver domain phosphotransfer. Hybrid HKs constitute non-canonical TCS signaling pathways, with transmitter and receiver domains within a single protein commu...

Developing safe nanomaterials has become a major concern in all the industry sectors using advanced materials. However, there are very few initiatives addressing this issue. The SERENADE project, with its long-term funding scheme, provided a unique opportunity to foster a coordinated, yet diverse approach to investigate the safe-by-design developme...

In the beneficial plant root-associated Pseudomonas brassicacearum strain NFM421, the GacS/GacA two-component system positively controls biofilm formation and the production of secondary metabolites through the synthesis of rsmX, rsmY and rsmZ. Here, we evidenced the genetic amplification of Rsm sRNAs by the discovery of a novel 110-nt long sRNA en...

Background First discovered on desert plants by Volkens 1887, rhizosheath formation, i.e. soil aggregation at the root surface, is now considered as a very promising adaptive trait to deal with abiotic stress. Indeed, the rhizosheath could help plants better cope with water stress, nitrogen and phosphorus deficiencies, and soil acidity. Scope We h...

The Paris Climate Agreements and Sustainable Development Goals, signed by 197 countries, present agendas and address key issues for implementing multi-scale responses for sustainable development under climate change—an effort that must involve local, regional, national, and supra-national stakeholders. In that regard, Continental Carbon Sequestrati...

Increased global warming, caused by climate change and human activities, will seriously hinder plant development, such as increasing salt concentrations in soils, which will limit water availability for plants. To ensure optimal plant growth under such changing conditions, microorganisms that improve plant growth and health must be integrated into...

Pearl millet is a cereal crop that is given a little attention by researchers despite its tremendous capabilities with respect to its pears (wheat, barley, ...). This plant cultivated in arid and semi-arid areas in Western Africa and Sahel resisting low rainfall and poor soil conditions is the main food and cheapest nutritive source for people livi...

Ramlibacter tataouinensis TTB310, a non-photosynthetic betaproteobacterium isolated from a semi-arid region of southern Tunisia, forms both rods and cysts. Cysts are resistant to desiccation and divide when water and nutrients are available. Rods are motile and capable of dissemination. Due to the strong correlation between sunlight and desiccation...

In the rhizosphere, complex and dynamic interactions occur between plants and microbial networks that are primarily mediated by root exudation. Plants exude various metabolites that may influence the rhizosphere microbiota. However, few studies have sought to understand the role of root exudation in shaping the functional capacities of the microbio...

In West Africa, farmers used pearl millet diversity to cope with climate change impact on rainfall distribution and water scarcity. However, in this selection-based adaptation, the interactions between the plant roots and rhizo-microbial communities were not taken in account. Indeed, these interactions that involve carbon root exudation in the rhiz...

The rhizosphere is the interface between plant roots and soil where intense, varied interactions between plants and microbes influence plants' health and growth through their influence on biochemical cycles, such as the carbon, nitrogen, and iron cycles. The rhizosphere is also a changing environment where oxygen can be rapidly limited and anaerobi...

Plant strategies for soil nutrient uptake have the potential to strongly influence plant–microbiota interactions, due to the competition between plants and microorganisms for soil nutrient acquisition and/or conservation. In the present study, we investigate whether these plant strategies could influence rhizosphere microbial activities via root ex...

Taxonomic affiliation of OTUs retrieved from heavy-DNA fractions (root exudate consumers): (file 1) shared by exploitative plants (DG, TF, BE, and AO) and representing the core microbiota; (file 2) present in AO only; (file 3) present in BE only; (file 4) present in DG only; (file 5) present in TF only.

Taxonomic affiliation of OTUs retrieved from light-DNA fractions (SOM degraders): (file 1) shared by conservative plants (FP and SC) and representing the core microbiota; (file 2) present in FP only; (file 3) present in SC only.

Taxonomic affiliation of OTUs retrieved from heavy-DNA fractions (root exudate consumers): (file 1) shared by exploitative (DG, BE, AO and TF) and conservative plants (FP and SC) and representing the core microbiota; (file 2) present in exploitative plants only; (file 3) present in conservative plants only.

Taxonomic affiliation of OTUs retrieved from root-DNA fractions (root exudate consumers): (file 1) shared by exploitative (DG, BE, AO and TF) and conservative plants (FP and SC) and representing the core microbiota; (file 2) present in exploitative plants only; (file 3) present in conservative plants only.

Principal coordinate analysis (PCoA) profile of the active bacterial diversity (using Bray–Curtis distances) colonizing the RAS and inhabiting the root tissues of Bromus erectus (BE), Anthoxanthum odoratum (AO), Dactylis glomerata (DG), Trisetum flavescens (TF), Festuca paniculata (FP), and Sesleria caerulea (SC). (A) PCoA of active microbiota obta...

Taxonomic affiliation of OTUs retrieved from light-DNA fractions (SOM degraders): (file 1) shared by exploitative (DG, BE, AO, and TF) and conservative plants (FP and SC) and representing the core microbiota; (file 2) present in exploitative plants only; (file 3) present in conservative plants only.

Table of the different bacteria present in the co-occurrence analysis (Figure 5). Each sheet displays the taxonomic affiliation of the bacterial communities uncovered for the RAS, including root exudate consumers of exploitative plant species (Exploit_heavy DNA fractions), root exudate consumers of conservative plant species (Cons_heavy DNA fractio...

Bacterial diversity in the rhizosphere of Bromus erectus (BE), Anthoxanthum odoratum (AO), Dactylis glomerata (DG), Trisetum flavescens (TF), Festuca paniculata (FP) and Sesleria caerulea (SC), as characterized by rarefaction curves of OTUs clustered using the swarm method with d = 3. H: heavy-DNA fraction; L: light-DNA fraction; R: root-DNA.

Taxonomic affiliation of OTUs retrieved from light-DNA fractions (SOM degraders): (file 1) shared by exploitative plants (DG, TF, BE, and AO) and representing the core microbiota; (file 2) present in AO only; (file 3) present in BE only; (file 4) present in DG only; (file 5) present in TF only.

Taxonomic affiliation of OTUs retrieved from heavy-DNA fractions (root exudate consumers): (file 1) shared by conservative plants (FP and SC) and representing the core microbiota; (file 2) present in FP only; (file 3) present in SC only.

Taxonomic affiliation of OTUs retrieved from root-DNA fractions (root exudate consumers): (file 1) shared by conservative plants (FP and SC) and representing the core microbiota; (file 2) present in FP only; (file 3) present in SC only.

Sample coverage, species richness and species diversity indices.

Taxonomic affiliation of OTUs retrieved from root-DNA fractions (root exudate consumers): (file 1) shared by exploitative plants (DG, TF, BE, and AO) and representing the core microbiota; (file 2) present in AO only; (file 3) present in BE only; (file 4) present in DG only; (file 5) present in TF only.

Les chercheurs de l'Initiative "4 pour 1000" réunis à Sète les 7 et 8 novembre 2018 lors de l’atelier "La recherche française autour du programme international de recherche de l’initiative 4 pour 1000 : les sols pour la sécurité alimentaire et le climat" ont lancé un appel pour un "programme scientifique ambitieux" pour la mise en œuvre du volet re...

Microbial phosphatase activity can trigger the precipitation of metal-phosphate minerals, a process called phosphatogenesis with global geochemical and environmental implications. An increasing diversity of phosphatases expressed by diverse microorganisms has been evidenced in various environments. However, it is challenging to link the functional...

Root exudation contributes to soil carbon allocation and also to microbial C and energy supply, which subsequently impacts soil aggregation around roots. Biologically-driven soil structural formation is an important driver of soil fertility. Plant genetic determinants of exudation and more generally of factors promoting rhizosphere soil aggregation...

The analysis of microbial diversity highlights the idea that tolerance of desiccation is more important than tolerance of temperature as an adaptive microbial trait for desert conditions. The culture-independent analysis of this microbial diversity in deserts revealed that 70–80 % of 16S-rDNA sequences do not match with described bacterial species,...

SERENADE is a French project which aims to develop and apply the "safer by design" process to create safer nano-products. It achieves this goal by combining knowledge and scientific approaches from a range of disciplines towards this common goal. This tutorial review presents the conceptual approach to "Safer by Design" and provides several example...

SERENADE is a French project which aims to develop and apply the " safer by design " process to create safer nano-products. It achieves this goal by combining knowledge and scientific approaches from a range of disciplines towards this common goal. This tutorial review presents the conceptual approach to " Safer by Design " and provides several exa...

Soils act as nanoceria sinks via agricultural spreading and surface waters. Canola plants were grown for one month in soil spiked with nanoceria (1 mg.kg-1). To define the role of nanomaterials design on environmental impacts, we studied nanoceria with different sizes (3.5 or 31 nm) and coating (citrate). We measured microbial activities involved i...

Although molecular techniques, including metagenomics, have revolutionized the study of microbial ecology, the sheer magnitude of soil microbial diversity has prevented full access to the scope and scale of relevant microbiology questions worth asking of this complex habitat. Indeed, we still lack the ability to link most microorganisms to their me...

The taxonomic position of nitrogen-fixing strains that were isolated from rhizosphere macerates of rice cultivated in the Binh Thanh region of Vietnam was determined by using polyphasic taxonomy. We determined the phylogenetic relationships of these organisms by performing DNA-rRNA hybridization experiments with a labeled rRNA probe from the type s...

Hydrogen production by microorganisms is often described as a promising sustainable and clean energy source, but still faces several obstacles, which prevent practical application. Among them, oxygen sensitivity of hydrogenases represents one of the major limitations hampering the biotechnological implementation of photobiological production proces...

TVV75, a strain of Burkholderia vietnamiensis, was isolated from an acid sulphate soil of south Vietnam, and selected for its high in vitro nitrogen fixation potential. This plant growth-promoting rhizobacterium (PGPR) had been used in a previously reported pot experiment. It was used in two new pot experiments and four field experiments to inocula...

The plant-beneficial bacterium Pseudomonas brassicacearum forms phenotypic variants in vitro as well as in planta during root colonization under natural conditions. Transcriptome analysis of typical phenotypic variants using microarrays containing coding as well as noncoding DNA fragments showed differential expression of several genes relevant to...

Prokaryotic microorganisms are known to be highly adaptable to diverse environmental conditions and to thrive in harsh environments. Halophilic microorganisms (Bacteria and Archaea) tolerate and grow in the presence of salt concentrations 10 times higher than seawater, whereas acidophiles withstand a pH of 1, and hyperthermophiles face temperatures...

Amount of EPS isolated from 5-day old R. alamii cultures (5 mL) in RCV medium (white bars) and in M9 modified medium (grey bars) supplemented with glucose (2 g.L−1). Mean of 3 replicates ± SD. (DOC)

Examples of UPLC chromatographs of cell extracts of R. alamii grown without cadmium to the beginning of the stationary phase.UPLC-PDA, HSS column. Eluent: A: 10 mM ammonium acetate pH 6.4, B: 20% 10 mM ammonium acetate in acetonitrile. Flow: 0.9 mL.min−1 (pressure drop 600–900 bar). Column temperature: 40°C. Injection: 5 µL, partial loop with needl...

Potential metabolites detected by ICR-FT MS negative ESI in R. alamii grown with 2 mg.L−1 of cadmium nitrate. (XLS)

Potential metabolites detected by ICR-FT MS positive ESI in R. alamii grown with 2 mg.L−1 of cadmium nitrate. (XLS)

Examples of off-line FTMS measurements. (DOC)

Potential metabolites detected by ICR-FT MS positive ESI in R. alamii grown with no cadmium nitrate. (XLS)