-
The Journal of Venomous Animals and... 2022Natural products represent important sources of antimicrobial compounds. Propolis and compounds from essential oils comprise good examples of such substances because of...
BACKGROUND
Natural products represent important sources of antimicrobial compounds. Propolis and compounds from essential oils comprise good examples of such substances because of their inhibitory effects on bacterial spores, including bee pathogens.
METHODS
Ethanol extracts of propolis (EEP) from were prepared using different methods: double ultrasonication, double maceration and maceration associated with ultrasonication. Together with the antimicrobial peptides nisin and melittin, and compounds present in the essential oils of clove () and cinnamon (), assays were carried out on one isolate and (ATCC 6344) against vegetative and sporulated forms, using the resazurin microtiter assay. Synergism with all the antimicrobials in association with tetracycline was verified by the time-kill curve method. Potassium and phosphate efflux, release of proteins and nucleic acids were investigated.
RESULTS
EEPs showed the same MIC, 156.25 µg/mL against and 78.12 µg/mL against . The peptides showed better activities against (MIC of 12 µg/mL for melittin and 37.50 µg/mL for nisin). Antimicrobials showed similar inhibitory effects, but cinnamaldehyde (39.06 µg/mL) showed the best action against . Melittin and nisin showed the greatest capacity to reduce spores, regarding there was a 100% reduction at 6.25 and 0.78 µg/mL, respectively. Concerning , the reduction was 93 and 98% at concentrations of 80 µg/mL of melittin and 15 µg/mL of nisin. EEPs showed the highest effects on the protein release against and . Nucleic acid release, phosphate and potassium efflux assays indicated bacterial cell membrane damage. Synergism between antimicrobials and tetracycline was demonstrated against both bacteria.
CONCLUSION
All antimicrobials tested showed antibacterial activities against vegetative and sporulated forms of and , especially nisin and melittin. Synergism with tetracycline and damage on bacterial cell membrane also occurred.
PubMed: 36118843
DOI: 10.1590/1678-9199-JVATITD-2022-0025 -
Microorganisms Jul 2022Considering a scenario where there is a low availability and increasing costs of fertilizers in the global agricultural market, as well as a finitude of important...
Considering a scenario where there is a low availability and increasing costs of fertilizers in the global agricultural market, as well as a finitude of important natural resources, such as phosphorus (P), this study tested the effect of the inoculation of rhizospheric or endophytic microorganisms isolated from and on the growth promotion of (L.) Merr. The tests were conducted in a controlled greenhouse system, and the effects of biofertilization were evaluated using the following parameters: dry biomass, nutritional content, and photochemical and photosynthetic performance of plants. Seed biopriming was performed with four bacterial and four fungal isolates, and the results were compared to those of seeds treated with the commercial product Biomaphos. Overall, microbial inoculation had a positive effect on biomass accumulation in , especially in strains PA12 (), SC5 (), and SC15 (). The non-inoculated control plants accumulated less nutrients, both in the whole plant and aerial part, and had reduced chlorophyll index and low photosynthetic rate () and photochemical efficiency. Strains PA12 (), SC5 (), and 328EF ( sp.) stood out in the optimization of nutrient concentration, transpiration rate, and stomatal conductance. Plants inoculated with the bacterial strains PA12 () and SC5 () and with the fungal strains 328EF ( sp.) and SC15 () showed the closest pattern to that observed in plants treated with Biomaphos, with the same trend of direction of the means associated with chlorophyll index, (), dry mass, and concentration of important nutrients such as N, P, and Mg. We recommend the use of these isolates in field tests to validate these strains for the production of biological inoculants as part of the portfolio of bioinputs available for .
PubMed: 35889105
DOI: 10.3390/microorganisms10071386 -
Plants (Basel, Switzerland) Jan 2021In the last two decades grapevine trunk diseases (GTDs) have emerged as the most significant threat for grapevine sustainability worldwide. The tracheomycotic fungus...
In the last two decades grapevine trunk diseases (GTDs) have emerged as the most significant threat for grapevine sustainability worldwide. The tracheomycotic fungus (Pch) is the predominant GTD-associated species and cannot be controlled with available chemicals. In the present study, we evaluated the effectiveness of two microbial strains ( K165 and F2) against Pch in grapevine. In vitro bioassays, performed in a growth culture medium simulating the xylem environment, indicated that F2 decreased Pch growth and sporulation, whereas K165 did not have any effect on Pch growth. experiments revealed that root-drench and stem-puncture application of K165 and F2 reduced the endophytic relative DNA amount of Pch by 90% and 82%, respectively, compared to controls. However, wood discoloration, the typical symptom of Pch infection, was not reduced in the F2 treated grapevines. Nevertheless, the F2 treated grapevines harbored higher lignin levels compared to mocks, as it was also done by K165. Therefore, F2 and K165 have the potential to be used as biocontrol agents against Pch in grapevines.
PubMed: 33499084
DOI: 10.3390/plants10020207 -
Frontiers in Microbiology 2022The rhizosphere is a highly complex and biochemically diverse environment that facilitates plant-microbe and microbe-microbe interactions, and this region is found...
Untargeted metabolite profiling to elucidate rhizosphere and leaf metabolome changes of wheat cultivars ( L.) treated with the plant growth-promoting rhizobacteria (T22) and .
The rhizosphere is a highly complex and biochemically diverse environment that facilitates plant-microbe and microbe-microbe interactions, and this region is found between plant roots and the bulk soil. Several studies have reported plant root exudation and metabolite secretion by rhizosphere-inhabiting microbes, suggesting that these metabolites play a vital role in plant-microbe interactions. However, the biochemical constellation of the rhizosphere soil is yet to be fully elucidated and thus remains extremely elusive. In this regard, the effects of plant growth-promoting rhizobacteria (PGPR)-plant interactions on the rhizosphere chemistry and above ground tissues are not fully understood. The current study applies an untargeted metabolomics approach to profile the rhizosphere exo-metabolome of wheat cultivars generated from seed inoculated (bio-primed) with (T22) and strains and to elucidate the effects of PGPR treatment on the metabolism of above-ground tissues. Chemometrics and molecular networking tools were used to process, mine and interpret the acquired mass spectrometry (MS) data. Global metabolome profiling of the rhizosphere soil of PGPR-bio-primed plants revealed differential accumulation of compounds from several classes of metabolites including phenylpropanoids, organic acids, lipids, organoheterocyclic compounds, and benzenoids. Of these, some have been reported to function in plant-microbe interactions, chemotaxis, biocontrol, and plant growth promotion. Metabolic perturbations associated with the primary and secondary metabolism were observed from the profiled leaf tissue of PGPR-bio-primed plants, suggesting a distal metabolic reprograming induced by PGPR seed bio-priming. These observations gave insights into the hypothetical framework which suggests that PGPR seed bio-priming can induce metabolic changes in plants leading to induced systemic response for adaptation to biotic and abiotic stress. Thus, this study contributes knowledge to ongoing efforts to decipher the rhizosphere metabolome and mechanistic nature of biochemical plant-microbe interactions, which could lead to metabolome engineering strategies for improved plant growth, priming for defense and sustainable agriculture.
PubMed: 36090115
DOI: 10.3389/fmicb.2022.971836 -
The Plant Pathology Journal Oct 2022This study was performed to reveal phenotypic characters and identity of symbiont bacteria of Nasutitermes as well as investigate their potential as antagonist of plant...
This study was performed to reveal phenotypic characters and identity of symbiont bacteria of Nasutitermes as well as investigate their potential as antagonist of plant pathogenic fungi. Isolation of the symbiont bacteria was carried out from inside the heads and the bodies of soldier and worker termite which were collected from 3 locations of nests. Identification was performed using phenotypic test and sequence of 16S ribosomal DNA (16S rDNA). Antagonistic capability was investigated in the laboratory against 3 phytopathogenic fungi i.e., Phytophthora capsici, Ganoderma boninense, and Rigidoporus microporus. Totally, 39 bacterial isolates were obtained from inside the heads and the bodies of Nasutitermes. All the isolates showed capability to inhibit growth of P. capsici, however, 34 isolates showed capability to inhibit growth of G. boninense and 32 isolates showed capability to inhibit growth of R. microporus. Two bacterial strains (IK3.1P and 1B1.2P) which showed the highest percentage of inhibition were further identified based on their sequence of 16S rDNA. The result showed that 1K3.1P strain was placed in the group of type strain and reference strains of Lysinibacillus fusiformis meanwhile 1B1.2P strain was grouped within type strain and reference strains Paenibacillus alvei. The result of this study supply valuable information on the role of symbiont bacteria of Nasutitermes, which may support the development of the control method of the three above-mentioned phytopathogenic fungi.
PubMed: 36221917
DOI: 10.5423/PPJ.OA.03.2022.0031 -
BMC Microbiology May 2011Bacteria use diverse signaling molecules to ensure the survival of the species in environmental niches. A variety of both gram-positive and gram-negative bacteria...
BACKGROUND
Bacteria use diverse signaling molecules to ensure the survival of the species in environmental niches. A variety of both gram-positive and gram-negative bacteria produce large quantities of indole that functions as an intercellular signal controlling diverse aspects of bacterial physiology.
RESULTS
In this study, we sought a novel role of indole in a gram-positive bacteria Paenibacillus alvei that can produce extracellular indole at a concentration of up to 300 μM in the stationary phase in Luria-Bertani medium. Unlike previous studies, our data show that the production of indole in P. alvei is strictly controlled by catabolite repression since the addition of glucose and glycerol completely turns off the indole production. The addition of exogenous indole markedly inhibits the heat resistance of P. alvei without affecting cell growth. Observation of cell morphology with electron microscopy shows that indole inhibits the development of spore coats and cortex in P. alvei. As a result of the immature spore formation of P. alvei, indole also decreases P. alvei survival when exposed to antibiotics, low pH, and ethanol. Additionally, indole derivatives also influence the heat resistance; for example, a plant auxin, 3-indolylacetonitrile dramatically (2900-fold) decreased the heat resistance of P. alvei, while another auxin 3-indoleacetic acid had a less significant influence on the heat resistance of P. alvei.
CONCLUSIONS
Together, our results demonstrate that indole and plant auxin 3-indolylacetonitrile inhibit spore maturation of P. alvei and that 3-indolylacetonitrile presents an opportunity for the control of heat and antimicrobial resistant spores of gram-positive bacteria.
Topics: Acetonitriles; Cell Wall; Growth Inhibitors; Indoles; Microscopy, Electron, Transmission; Paenibacillus; Signal Transduction; Spores, Bacterial
PubMed: 21619597
DOI: 10.1186/1471-2180-11-119 -
Biomolecules Nov 2021Ketalpyruvyltransferases belong to a widespread but little investigated class of enzymes, which utilise phosphoenolpyruvate (PEP) for the pyruvylation of saccharides....
Ketalpyruvyltransferases belong to a widespread but little investigated class of enzymes, which utilise phosphoenolpyruvate (PEP) for the pyruvylation of saccharides. Pyruvylated saccharides play pivotal biological roles, ranging from protein binding to virulence. Limiting factors for the characterisation of ketalpyruvyltransferases are the availability of cognate acceptor substrates and a straightforward enzyme assay. We report on a fast ketalpyruvyltransferase assay based on the colorimetric detection of phosphate released during pyruvyltransfer from PEP onto the acceptor via complexation with Malachite Green and molybdate. To optimise the assay for the model 4,6-ketalpyruvyl::ManNAc-transferase CsaB from , a β-d-ManNAc-α-d-GlcNAc-diphosphoryl-11-phenoxyundecyl acceptor mimicking an intermediate of the bacterium's cell wall glycopolymer biosynthesis pathway, upon which CsaB is naturally active, was produced chemo-enzymatically and used together with recombinant CsaB. Optimal assay conditions were 5 min reaction time at 37 °C and pH 7.5, followed by colour development for 1 h at 37 °C and measurement of absorbance at 620 nm. The structure of the generated pyruvylated product was confirmed by NMR spectroscopy. Using the established assay, the first kinetic constants of a 4,6-ketalpyuvyl::ManNAc-transferase could be determined; upon variation of the acceptor and PEP concentrations, a of 19.50 ± 3.50 µM and of 0.21 ± 0.01 s as well as a of 258 ± 38 µM and a of 0.15 ± 0.01 s were revealed. CsaB was inactive on synthetic NP-β-d-ManNAc and β-d-ManNAc-β-d-GlcNAc-1-Me, supporting the necessity of a complex acceptor substrate.
Topics: Catalysis; Hexosamines; Paenibacillus; Phosphates; Phosphoenolpyruvate
PubMed: 34827730
DOI: 10.3390/biom11111732 -
Open Life Sciences 2020Cellulosic date palm wastes may have beneficial biotechnological applications for eco-friendly utilization. This study reports the isolation of thermophilic...
Cellulosic date palm wastes may have beneficial biotechnological applications for eco-friendly utilization. This study reports the isolation of thermophilic cellulase-producing bacteria and their application in lactic acid production using date palm leaves. The promising isolate was identified as by 16S rRNA gene sequencing. Maximum cellulase production was acquired using alkaline treated date palm leaves (ATDPL) at 48 h and yielded 4.50 U.mL FPase, 8.11 U.mL CMCase, and 2.74 U.mL β-glucosidase. The cellulase activity was optimal at pH 5.0 and 50°C with good stability at a wide temperature (40-70°C) and pH (4.0-7.0) range, demonstrating its suitability in simultaneous saccharification and fermentation. Lactic acid fermentation was optimized at 4 days, pH 5.0, 50°C, 6.0% cellulose of ATDPL, 30 FPU/ g cellulose, 1.0 g. L Tween 80, and 5.0 g. L yeast extract using . The conversion efficiency of lactic acid from the cellulose of ATDPL was 98.71%, and the lactic acid productivity was 0.719 g. L h. Alkaline treatment exhibited a valuable effect on the production of cellulases and lactic acid by reducing the lignin content and cellulose crystallinity. The results of this study offer a credible procedure for using date palm leaves for microbial industrial applications.
PubMed: 33987475
DOI: 10.1515/biol-2020-0019 -
Scientific Reports Aug 2023Pyruvylation is a biologically versatile but mechanistically unexplored saccharide modification. 4,6-Ketal pyruvylated N-acetylmannosamine within bacterial secondary...
Pyruvylation is a biologically versatile but mechanistically unexplored saccharide modification. 4,6-Ketal pyruvylated N-acetylmannosamine within bacterial secondary cell wall polymers serves as a cell wall anchoring epitope for proteins possessing a terminal S-layer homology domain trimer. The pyruvyltransferase CsaB from Paenibacillus alvei served as a model to investigate the structural basis of the pyruvyltransfer reaction by a combination of molecular modelling and site-directed mutagenesis together with an enzyme assay using phosphoenolpyruvate (PEP; donor) and synthetic β-D-ManNAc-(1 → 4)-α-D-GlcNAc-diphosphoryl-11-phenoxyundecyl (acceptor). CsaB protein structure modelling was done using Phyre2 and I-Tasser based on the partial crystal structure of the Schizosaccharomyces pombe pyruvyltransferase Pvg1p and by AlphaFold. The models informed the construction of twelve CsaB mutants targeted at plausible PEP and acceptor binding sites and K and k values were determined to evaluate the mutants, indicating the importance of a loop region for catalysis. R148, H308 and K328 were found to be critical to PEP binding and insight into acceptor binding was obtained from an analysis of Y14 and F16 mutants, confirming the modelled binding sites and interactions predicted using Molecular Operating Environment. These data lay the basis for future mechanistic studies of saccharide pyruvylation as a novel target for interference with bacterial cell wall assembly.
Topics: Paenibacillus; Bacillus; Mutagenesis, Site-Directed; Binding Sites
PubMed: 37591902
DOI: 10.1038/s41598-023-40072-1 -
Glycobiology Jan 2016Flagellin glycosylation impacts, in several documented cases, the functionality of bacterial flagella. The basis of flagellin glycosylation has been studied for various...
Flagellin glycosylation impacts, in several documented cases, the functionality of bacterial flagella. The basis of flagellin glycosylation has been studied for various Gram-negative bacteria, but less is known about flagellin glycans of Gram-positive bacteria including Paenibacillus alvei, a secondary invader of honeybee colonies diseased with European foulbrood. Paenibacillus alvei CCM 2051(T) swarms vigorously on solidified culture medium, with swarming relying on functional flagella as evidenced by abolished biofilm formation of a non-motile P. alvei mutant defective in the flagellin protein Hag. Here, the glycobiology of the polar P. alvei flagella was investigated. Analysis on purified flagellin demonstrated that the 30-kDa Hag protein (PAV_2c01710) is modified with an O-linked trisaccharide comprised of one hexose and two N-acetyl-hexosamine residues, at three sites of glycosylation. Downstream of the hag gene on the bacterial chromosome, two open reading frames (PAV_2c01630, PAV_2c01640) encoding putative glycosyltransferases were shown to constitute a flagellin glycosylation island. Mutants defective in these genes exhibited altered migration in sodium dodecyl sulfate polyacrylamide gel electrophoresis as well as loss of extracellular flagella production and bacterial motility. This study reveals that flagellin glycosylation in P. alvei is pivotal to flagella formation and bacterial motility in vivo, and simultaneously identifies flagella glycosylation as a second protein O-glycosylation system in this bacterium, in addition to the well-investigated S-layer tyrosine O-glycosylation pathway.
Topics: Amino Acid Sequence; Bacterial Proteins; Flagellin; Glycosylation; Glycosyltransferases; Hexoses; Molecular Sequence Data; Mutation; Paenibacillus; Protein Processing, Post-Translational
PubMed: 26405108
DOI: 10.1093/glycob/cwv087