Activity of bacterial seed endophytes of landrace durum wheat for control of Fusarium foot rot

Five bacterial endophytic isolates obtained from durum wheat seeds (Iandrace "Timilia reste nere") and identified as belonging to Pantoea (isolates A1, F7, F15 and GI) and Paenibacillus (isolate B) genera on the basis of 16S rDNA gene sequences, were assayed in vitro and in vivo for their ability to inhibit Fusarium culmorum growth and the disease (Fusarium foot rot) it causes in durum wheat. All isolates significantly reduced in vitro growth of F. culmorum in comparison with the control. After 120 hours of incubation, isolates B and GI showed the greatest mycelial growth inhibition, i.e., respectively, 76 and 74%. When durum wheat "Simeto" seeds were treated with bacterial isolates singly or in combinations and then inoculated with F. culmorum, all treatments with endophytes showed increased, but not statistically significant, seed germination. Except for isolate Al, all bacterial isolates stimulated vegetative parameters of durum wheat seedlings. Mixture of isolates F7 + F15 was the most effective in improving shoot height (+94%), root length (+47%) and vigour index (+81%). Mixture of isolates A1 + B reduced Fusarium foot rot incidence (-21%) and severity (-30%), and isolate A1 reduced incidence (-15%) and severity (-16%) of the disease. These results indicate potential of bacterial seed endophytes, identified in this study, for control of Fusarium foot rot and suggest that bacterial seed endophytes may provide a new biocontrol agent for an environmentally sustainable durum wheat disease management programme

Unravelling the DNA sequences carried by Streptomyces coelicolor membrane vesicles

Membrane vesicles (MVs) are spherical particles with nanoscale dimensions and characterized by the presence of diverse cargos, such as nucleic acids, proteins, lipids, and cellular metabolites. Many examples of (micro)organisms producing MVs are reported in literature. Among them, bacterial MVs are of particular interest because they are now considered as the fourth mechanism of horizontal gene transfer. Streptomyces bacteria are well-known for their ecological roles and ability to synthesize bioactive compounds, with Streptomyces coelicolor being the model organism. It was previously demonstrated that it can produce distinct populations of MVs characterized by different protein and metabolite cargos. In this work we demonstrated for the first time that MVs of S. coelicolor carry both DNA and RNA and that their DNA content represents the entire chromosome of the bacterium. These findings suggest that MV DNA could have a role in the evolution of Streptomyces genomes and that MVs could be exploited in new strain engineering strategies

A small protein is involved in tryptophan biosynthesis and morpho-physiological differentiation in Streptomyces coelicolor

A small protein is involved in tryptophan biosynthesis and morpho-physiological differentiation in Streptomyces coelicolo

The endophytic microbiota of Citrus limon is transmitted from seed to shoot highlighting differences of bacterial and fungal community structures

Citrus limon (L.) Burm. F. is an important evergreen fruit crop whose rhizosphere and phyllosphere microbiota have been characterized, while seed microbiota is still unknown. Bacterial and fungal endophytes were isolated from C. limon surface-sterilized seeds. The isolated fungi—belonging to Aspergillus, Quambalaria and Bjerkandera genera—and bacteria—belonging to Staphylococcus genus—were characterized for indoleacetic acid production and phosphate solubilization. Next Generation Sequencing based approaches were then used to characterize the endophytic bacterial and fungal microbiota structures of surface-sterilized C. limon seeds and of shoots obtained under aseptic conditions from in vitro growing seedlings regenerated from surface-sterilized seeds. This analysis highlighted that Cutibacterium and Acinetobacter were the most abundant bacterial genera in both seeds and shoots, while Cladosporium and Debaryomyces were the most abundant fungal genera in seeds and shoots, respectively. The localization of bacterial endophytes in seed and shoot tissues was revealed by Fluorescence In Situ Hybridization coupled with Confocal Laser Scanning Microscopy revealing vascular bundle colonization. Thus, these results highlighted for the first time the structures of endophytic microbiota of C. limon seeds and the transmission to shoots, corroborating the idea of a vertical transmission of plant microbiota and suggesting its crucial role in seed germination and plant development

Composition and geographic variation of the bacterial microbiota associated with the coelomic fluid of the sea urchin Paracentrotus lividus

In the present work, culture-based and culture-independent investigations were performed to determine the microbiota structure of the coelomic fluid of Mediterranean sea urchin Paracentrotus lividus individuals collected from two distinct geographical sites neighboring a high-density population bay and a nature reserve, respectively. Next Generation Sequencing analysis of 16S rRNA gene (rDNA) showed that members of the Proteobacteria, Bacteroidetes and Fusobacteria phyla, which have been previously reported to be commonly retrieved from marine invertebrates, dominate the overall population of microorganisms colonizing this liquid tissue, with minority bacterial genera exhibiting remarkable differences among individuals. Our results showed that there is a correlation between microbiota structure and geographical location of the echinoderm collection site, highlighting over-representation of metagenomic functions related to amino acid and bioactive peptides metabolism in specimens inhabiting the nature reserve. Finally, we also described the developmental delay and aberrations exhibited by sea urchin embryos exposed to distinct bacterial isolates, and showed that these defects rely upon hydrophilic compound(s) synthesized by the bacterial strains assayed. Altogether, our findings lay the groundwork to decipher the relationships of bacteria with sea urchins in their aquatic environment, also providing an additional layer of information to understand the biological roles of the coelomic fluid

Metabolic pathways and regulatory networks associated to NAI-107 lantibiotic production in Microbispora sp. ATCC-PTA-5024

The filamentous actinobacterium Microbispora sp. ATCC-PTA-5024 produces the lantibiotic NAI-107, which is effective against multidrugresistant Gram-positive pathogens. In actinomycetes, the biosynthesis of antibiotics is elicited as a physiological response that is controlled by a complex regulatory network involving general and pathwayspecific regulators. The \u2018omics technologies can be useful to explore molecular physiology in bacterial cells and elucidate molecular and metabolic events associated to antibiotic production in order to develop robust and economically-feasible production processes. To this aim, differential proteomic analyses, based two-dimensional difference in gel electrophoresis (2D-DIGE) and mass spectrometry (MS) approaches, combined with differential fluorescence microscopy (DFM) and molecular genetic studies were carried out on M. sp. ATCC-PTA-5024. M. sp. ATCC-PTA-5024 fermentations, showing a first biomass accumulation (A) stage followed by a of biomass yield decline (D) stage, revealed that NAI-107 yield starts at mid A stage and increases up to mid D stage. 2D-DIGE and MS analyses were carried out at A and D stages to reveal patterns of differentially regulated proteins associated to on set and maintenance of NAI-107 production, respectively. Regulatory and metabolic proteins were identified and possible role in physiological differentiation of an unknown regulatory protein was investigated by the construction of an over-expressing strain. Impact of NAI-107 on cell physiology and metabolism was analysed using a non-producing mutant confirming possible role of identified proteins in self-resistance mechanism. Molecular aspect of activation of specific stress response mechanism were confirmed by DFM. These results originally elucidate regulatory networks, biochemical pathways and molecular processes occurring during growth and lantibiotic production, thus providing the first functional picture of a member of the Microbispora genus