sp. nov. and sp. nov., two flavobacteria from the epiphytic microbiota of the brown alga , and emended description of the genus .

Four marine bacterial strains were isolated from a thallus of the brown alga collected in Roscoff, France. Cells were Gram-stain-negative, strictly aerobic, non-flagellated, gliding, rod-shaped and grew optimally at 25-30 °C, at pH 7-8 and with 2-4 % NaCl. Phylogenetic analyses of their 16S rRNA gene sequences showed that the bacteria were affiliated to the genus (family , phylum ).

Nonribosomal peptides in fungal cell factories: from genome mining to optimized heterologous production.

Fungi are notoriously prolific producers of secondary metabolites including nonribosomal peptides (NRPs). The structural complexity of NRPs grants them interesting activities such as antibiotic, anti-cancer, and anti-inflammatory properties. The discovery of these compounds with attractive activities can be achieved by using two approaches: either by screening samples originating from various environments for their biological activities, or by identifying the related clusters in genomic sequences thanks to bioinformatics tools.

Astin C Production by the Endophytic Fungus Cyanodermella asteris in Planktonic and Immobilized Culture Conditions.

The fungal endophyte Cyanodermella asteris (C. asteris) has been recently isolated from the medicinal plant Aster tataricus (A. tataricus).

Temporal Dynamics of Soil Microbial Communities below the Seedbed under Two Contrasting Tillage Regimes.

Agricultural productivity relies on a wide range of ecosystem services provided by the soil biota. Plowing is a fundamental component of conventional farming, but long-term detrimental effects such as soil erosion and loss of soil organic matter have been recognized. Moving towards more sustainable management practices such as reduced tillage or crop residue retention can reduce these detrimental effects, but will also influence structure and function of the soil microbiota with direct consequences for the associated ecosystem services.

Discovering novel enzymes by functional screening of plurigenomic libraries from alga-associated Flavobacteriia and Gammaproteobacteria.

Alga-associated microorganisms, in the context of their numerous interactions with the host and the complexity of the marine environment, are known to produce diverse hydrolytic enzymes with original biochemistry. We recently isolated several macroalgal-polysaccharide-degrading bacteria from the surface of the brown alga Ascophyllum nodosum. These active isolates belong to two classes: the Flavobacteriia and the Gammaproteobacteria.

The Cultivable Surface Microbiota of the Brown Alga Ascophyllum nodosum is Enriched in Macroalgal-Polysaccharide-Degrading Bacteria.

Bacteria degrading algal polysaccharides are key players in the global carbon cycle and in algal biomass recycling. Yet the water column, which has been studied largely by metagenomic approaches, is poor in such bacteria and their algal-polysaccharide-degrading enzymes. Even more surprisingly, the few published studies on seaweed-associated microbiomes have revealed low abundances of such bacteria and their specific enzymes.

Isolation and cultivation of xylanolytic and cellulolytic Sarocladium kiliense and Trichoderma virens from the gut of the termite Reticulitermes santonensis.

The purpose of this work was the isolation and cultivation of cellulolytic and xylanolytic microorganisms extracted from the gut of the lower termite Reticulitermes santonensis. Microcrystalline cellulose (with and without lignin) and beech wood xylan were used as diets instead of poplar wood in order to select cellulose and hemicellulose-degrading fungi. The strain Sarocladium kiliense (Acremonium kiliense) CTGxxyl was isolated from the termites fed on xylan, while the strain Trichoderma virens CTGxAviL was isolated from the termites fed on cellulose (with and without lignin).

Diversity of bacterial communities in a profile of a winter wheat field: known and unknown members.

In soils, bacteria are very abundant and diverse. They are involved in various agro-ecosystem processes such as the nitrogen cycle, organic matter degradation, and soil formation. Yet, little is known about the distribution and composition of bacterial communities through the soil profile, particularly in agricultural soils, as most studies have focused only on topsoils or forest and grassland soils.

Identification and characterization of a halotolerant, cold-active marine endo-β-1,4-glucanase by using functional metagenomics of seaweed-associated microbiota.

A metagenomic library was constructed from microorganisms associated with the brown alga Ascophyllum nodosum. Functional screening of this library revealed 13 novel putative esterase loci and two glycoside hydrolase loci. Sequence and gene cluster analysis showed the wide diversity of the identified enzymes and gave an idea of the microbial populations present during the sample collection period.

Widespread occurrence of expressed fungal secretory peroxidases in forest soils.

Fungal secretory peroxidases mediate fundamental ecological functions in the conversion and degradation of plant biomass. Many of these enzymes have strong oxidizing activities towards aromatic compounds and are involved in the degradation of plant cell wall (lignin) and humus. They comprise three major groups: class II peroxidases (including lignin peroxidase, manganese peroxidase, versatile peroxidase and generic peroxidase), dye-decolorizing peroxidases, and heme-thiolate peroxidases (e.

MALDI-TOF MS analysis of cellodextrins and xylo-oligosaccharides produced by hindgut homogenates of Reticulitermes santonensis.

Hindgut homogenates of the termite Reticulitermes santonensis were incubated with carboxymethyl cellulose (CMC), crystalline celluloses or xylan substrates. Hydrolysates were analyzed with matrix-assisted laser desorption/ionization coupled to time-of-flight mass spectrometry (MALDI-TOF MS). The method was first set up using acid hydrolysis analysis to characterize non-enzymatic profiles.

Microorganisms living on macroalgae: diversity, interactions, and biotechnological applications.

Marine microorganisms play key roles in every marine ecological process, hence the growing interest in studying their populations and functions. Microbial communities on algae remain underexplored, however, despite their huge biodiversity and the fact that they differ markedly from those living freely in seawater. The study of this microbiota and of its relationships with algal hosts should provide crucial information for ecological investigations on algae and aquatic ecosystems.

Two promising alkaline β-glucosidases isolated by functional metagenomics from agricultural soil, including one showing high tolerance towards harsh detergents, oxidants and glucose.

New β-glucosidase activities were identified by screening metagenomic libraries constructed with DNA isolated from the topsoil of a winter wheat field. Two of the corresponding proteins, displaying an unusual preference for alkaline conditions, were selected for purification by Ni-NTA chromatography. AS-Esc6, a 762-amino-acid enzyme belonging to glycoside hydrolase family 3, proved to be a mesophilic aryl-β-glucosidase with maximal activity around pH 8 and 40 °C.

Isolation of amylolytic, xylanolytic, and cellulolytic microorganisms extracted from the gut of the termite Reticulitermes santonensis by means of a micro-aerobic atmosphere.

The aim of this work was to isolate enzyme-producing microorganisms from the tract of the termite Reticulitermes santonensis. The microorganisms were extracted from the guts and anaerobic (CO₂ or CO₂/H₂) and micro-aerobic atmospheres were used to stimulate growth. Three different strategies were tried out.

Symbiont diversity in Reticulitermes santonensis (Isoptera: Rhinotermitidae): investigation strategy through proteomics.

The complex microbial community living in the hindgut of lower termites includes prokaryotes, flagellates, yeasts, and filamentous fungi. Many microorganisms are found in the termite gut, but only a few are thought to be involved in symbiotic association to participate in cellulose digestion. Proteomics provides analyses from both taxonomical and functional perspectives.

Characterization of a new oxidant-stable serine protease isolated by functional metagenomics.

A novel serine protease gene, SBcas3.3, was identified by functional screening of a forest-soil metagenomic library on agar plates supplemented with AZCL-casein. Overproduction in Escherichia coli revealed that the enzyme is produced as a 770-amino-acid precursor which is processed to a mature protease of ~55 kDa.

Isolation and cultivation of a xylanolytic Bacillus subtilis extracted from the gut of the termite Reticulitermes santonensis.

The aim of this work was the isolation of xylanolytic microorganisms from the digestive tract of the termite Reticulitermes santonensis. The reducing sugars released after the hydrolysis of xylans can be further fermented to provide bioethanol. A xylanolytic strain of Bacillus subtilis was isolated from the hindgut of the termite and displayed amylase and xylanase activities.

Bacillus subtilis as a tool for screening soil metagenomic libraries for antimicrobial activities.

Finding new antimicrobial activities by functional metagenomics has been shown to depend on the heterologous host used to express the foreign DNA. Therefore, efforts are devoted to developing new tools for constructing metagenomic libraries in shuttle vectors replicatable in phylogenetically distinct hosts. Here we evaluated the use of the Escherichia coli-Bacillus subtilis shuttle vector pHT01 to construct a forest-soil metagenomic library.

An eYFP reporter gene for the yeast two-hybrid system.

The yeast two-hybrid system is a powerful tool for detecting binary protein interactions, widely used in large-scale interactome mapping. We modified two yeast strains commonly used in yeast two-hybrid experiments by integrating into their genomes a new reporter gene encoding the enhanced yellow fluorescent protein eYFP. The suitability of this reporter gene for interaction screening was evaluated by fluorescence microscopy and fluorescence-activated cell sorting analysis.

Characterization of three new carboxylic ester hydrolases isolated by functional screening of a forest soil metagenomic library.

Three new lipolytic genes were isolated from a forest soil metagenomic library by functional screening on tributyrin agar plates. The genes SBLip1, SBLip2 and SBLip5.1 respectively encode polypeptides of 445, 346 and 316 amino acids.

Interaction network of antimicrobial peptides of Arabidopsis thaliana, based on high-throughput yeast two-hybrid screening.

One mechanism used by plants to respond to infection is the production of antimicrobial peptides (AMPs). In addition to a role in defence, AMPs seem to have other biological functions. Furthermore, the number of cysteine-rich AMP-like peptides appears to have been underpredicted in plant genomes.

Identification and characterization of a new xylanase from Gram-positive bacteria isolated from termite gut (Reticulitermes santonensis).

Termites are world champions at digesting lignocellulosic compounds, thanks to cooperation between their own enzymes and exogenous enzymes from microorganisms. Prokaryotic cells are responsible for a large part of this lignocellulolytic activity. Bacterial enzyme activities have been demonstrated in the higher and the lower termite gut.

New glucosidase activities identified by functional screening of a genomic DNA library from the gut microbiota of the termite Reticulitermes santonensis.

β-Glucosidases are widely distributed in living organisms and play a major role in the degradation of wood, hydrolysing cellobiose or cello-oligosaccharides to glucose. Termites are among the rare animals capable of digesting wood, thanks to enzyme activities of their own and to enzymes produced by their gut microbiota. Many bacteria have been identified in the guts of lower termites, some of which possess cellulolytic or/and hemicellulolytic activity, required for digesting wood.

Characterization of a new β-glucosidase/β-xylosidase from the gut microbiota of the termite (Reticulitermes santonensis).

The gut of the termite Reticulitermes santonensis contains an interesting diversity of prokaryotic and eukaryotic microorganisms not found elsewhere. These microorganisms produce many enzyme-digesting lignocellulosic compounds, probably in cooperation with endogenous enzymes. Regarding cellulose and hemicellulose digestion in the termite gut, much remains to be learned about the relative contributions of termite enzymes and enzymes produced by different microorganisms.