Project description:Bacillus amyloliquefaciens FZB42 is a representative organism for Gram positive soil bacteria associated with plant roots and beneficial to plant growth. It is of immense importance to understand mechanisms of this class of bacteria adapting to rhizosphere. In this work employing differential RNA sequencing (RNA-seq) and Northern blot, we systematically identified transcription start sites of mRNAs as well as non-coding regulatory RNAs in FZB42. The genes regulated at different growth phases and located in polycistronic operons were also identified. A set of genes were re-annotated. In addition, a sRNA named Bas01 was identified to be involved in Bacillus sporulation and biofilm formation. The result we obtained provides valuable data for investigation of Bacillus gene expression and molecular details of rhizobacterial interaction with host plants.
Project description:The natural biotope of Bacillus subtilis is the upper layer of soil where it grows as a biofilm. To mimic this physiological development and study the impact of nanoparticles during the formation of a biofilm in a contaminated soil, we have studied the proteomic response of the ancestral strain Bacillus subtilis 3610, which is able to form biofilm contrary to the 168 laboratory strain. The bacteria were grown on soft agar plates containing n-ZnO, n-TiO2 or ZnSO4 metal ion.
Project description:Bacillus amyloliquefaciens FZB42 is a representative organism for Gram positive soil bacteria associated with plant roots and beneficial to plant growth. It is of immense importance to understand mechanisms of this class of bacteria adapting to rhizosphere. In this work employing differential RNA sequencing (RNA-seq) and Northern blot, we systematically identified transcription start sites of mRNAs as well as non-coding regulatory RNAs in FZB42. The genes regulated at different growth phases and located in polycistronic operons were also identified. A set of genes were re-annotated. In addition, a sRNA named Bas01 was identified to be involved in Bacillus sporulation and biofilm formation. The result we obtained provides valuable data for investigation of Bacillus gene expression and molecular details of rhizobacterial interaction with host plants. Examination of transcriptome profile of rhizobacterium B. amyloliquefaciens FZB42 grown under six conditions.
Project description:Plant growth-promoting rhizobacteria (PGPR) are soil beneficial microorganisms that colonize plant roots for nutritional purposes and accordingly benefit plants by increasing plant growth or reducing disease. But it still remains unclear which mechanisms or pathways are involved in the interactions between PGPR and plants. To understand the complex plant-PGPR interactions, the changes in the transcriptome of typical PGPR standard Bacillus subtilis in responding to rice seedlings were analyzed. We compared and anylyzed the transcriptome changes of the bacteria Bacillus subtilis OKB105 in response to rice seedings for 2 h. Total RNA was extracted and Random priming cDNA synthesis, cDNA fragmentation and terminal labeling with biotinylated GeneChip DNA labeling reagent, and hybridization to the Affymetrix GeneChip Bacillus subtilis Genome Array.
Project description:It is well-known that individual pea (Pisum sativum L.) cultivars differ in their symbiotic responsivity. This trait is typically manifested with an increase in seed weights due to inoculation with rhizobial bacteria and arbuscular mycorrhizal fungi. The aim of this work was to characterize the alterations in root proteome of highly responsive pea genotype k-8274 and low-responsive genotype k-3358 grown in non-sterile soil, which were associated with root colonization with rhizobial bacteria and arbuscular mycorrhiza fungi in comparison to proteome shifts caused by soil supplementation with mineral nitrogen salts. Our results clearly indicate that supplementation of the soil with mineral nitrogen-containing salts switched the root proteome of both genotypes to assimilation of the available nitrogen, whereas the processes associated with nitrogen fixation were suppressed. Surprisingly, inoculation with rhizobial bacteria had only a minor effect on root proteomes of the both genotypes. The most pronounced response was observed for highly responsive k-8274 genotype inoculated simultaneously with rhizobial bacteria and arbuscular mycorrhizal fungi. This response involved activation of the proteins related to redox metabolism and suppression of excessive nodule formation. In turn, the low-responsive genotype k-3358 demonstrated a pronounced inoculation-induced suppression of protein metabolism and enhanced diverse defense reactions in pea roots under the same soil conditions. The results of the study shed light on the molecular basis of differential symbiotic responsivity in different pea cultivars.
Project description:Interaction of microbes affects the growth, metabolism and differentiation of members of the community. While direct and indirect competitions, like spite and nutrient consumption have negative effect on each other, microbes also evolved in nature not only to fight, but in some cases to adapt or support each other while increasing the fitness of the community. Presence of bacteria and fungi in the soil results in interactions and various examples were described, including mutualism. Bacilli attach to the plant root and form complex communities in the rhizosphere. Bacillus subtilis, when grown in the presence of Aspergillus niger interacts with the fungal partner, attaches and grows on the hyphae. Using dual transcriptome experiment, we show that both fungi and bacteria alter their metabolisms during the interaction. Interestingly, the transcription of genes related to the antifungal and antibacterial defense mechanism of B. subtilis and A. niger, respectively, are decreased upon attachment of bacteria to the mycelia. Our microarray experiments provide a novel insight into the mutual interaction of a bacterium and a fungus. Aspergillus niger were grown with and without Bacillus subtilis. Biological triplicates were made for both conditions, Affymetrix microarray experiments were performed on these samples.
Project description:The nucleotide messenger (p)ppGpp allows bacteria to adapt to fluctuating environments by reprogramming the transcriptome. Despite its well-recognized role in gene regulation, (p)ppGpp is only known to directly affect transcription in Proteobacteria by binding to the RNA polymerase. Here we reveal a different mechanism of gene regulation by (p)ppGpp in Firmicutes from soil bacteria to pathogens: (p)ppGpp directly binds to the transcription factor PurR to downregulate purine biosynthesis. We identified PurR as a receptor of (p)ppGpp in Bacillus anthracis and revealed that (p)ppGpp strongly enhances PurR binding to its regulon in the Bacillus subtilis genome. A co-structure reveals that (p)ppGpp binds to a PurR pocket reminiscent of the active site of PRT enzymes that has been repurposed to serve a purely regulatory role, where the effectors (p)ppGpp and PRPP compete to allosterically control transcription. PRPP inhibits PurR DNA binding to induce transcription of purine synthesis genes, whereas (p)ppGpp antagonizes PRPP to enhance PurR DNA binding and repress transcription. A (p)ppGpp-refractory purR mutant fails to downregulate purine synthesis genes upon starvation. Our work establishes the precedent of (p)ppGpp as a classical effector of transcription repressors and reveals the key function of (p)ppGpp in regulating nucleotide synthesis through gene regulation, from the human intestinal tract to host-pathogen interfaces.
Project description:Rhizosphere is a complex system of interactions between plant roots, bacteria, fungi and animals, where the release of plant root exudates stimulates bacterial density and diversity. However, the majority of the bacteria in soil results to be unculturable but active. The aim of the present work was to characterize the microbial community associated to the root of V. vinifera cv. Pinot Noir not only under a taxonomic perspective, but also under a functional point of view, using a metaproteome approach. Our results underlined the difference between the metagenomic and metaproteomic approach and the large potentiality of proteomics in describing the environmental bacterial community and its activity. In fact, by this approach, that allows to investigate the mechanisms occurring in the rhizosphere, we showed that bacteria belonging to Streptomyces, Bacillus and Pseudomonas genera are the most active in protein expression. In the rhizosphere, the identified genera were involved mainly in phosphorus and nitrogen soil metabolism.
Project description:In order to get insights into the ability of ectomycorrhizal fungi to perceive their biotic environment as well as into the mechanisms of the interactions between ectomycorrhizal fungi and soil bacteria, we analysed the transcriptomic response of the ectomycorrhizal fungus L. bicolor and of two beneficial, and neutral soil bacteria during their interactions in vitro.