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1.
Int Microbiol ; 24(3): 399-413, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33956240

RESUMO

Bdellovibrios are predatory bacteria that invade other live Gram-negative bacterial cells for growth and reproduction. They have recently been considered as potential living antibiotics and biocontrol agents. In this study, the predatory activity and biocontrol potency of Bdellovibrio bacteriovorus strain SOIR-1 against Pantoea sp. strain BCCS and Xanthomonas campestris, two exo-biopolymer-producing phytopathogens, was evaluated. Plaque formation assays and lysis analysis in the broth co-cultures were used for the in vitro evaluation of bacteriolytic activity of strain SOIR-1. The in vivo biocontrol potential of strain SOIR-1 was evaluated by pathogenicity tests on the onion bulbs and potato tuber slices. The phytopathogens were also recovered from the infected plant tissues and confirmed using biochemical tests and PCR-based 16S rRNA gene sequence analysis. Typical bdellovibrios plaques were developed on the lawn cultures of Pantoea sp. BCCS and X. campestris. The killing rate of strain SOIR-1 toward Pantoea sp. BCCS and X. campestris was 84.3% and 76.3%, respectively. Exo-biopolymers attenuated the predation efficiency of strain SOIR-1 up to 10.2-18.2% (Pantoea sp. BCCS) and 12.2-17.3% (X. campestris). The strain SOIR-1 significantly reduced rotting symptoms in the onion bulbs caused by Pantoea sp. BCCS (69.0%) and potato tuber slices caused by X. campestris (73.1%). Although more field assessments are necessary, strain SOIR-1 has the preliminary potential as a biocontrol agent against phytopathogenic Pantoea sp. BCCS and X. campestris, especially in postharvest storage. Due to the particular physicochemical properties of evaluated exo-biopolymers, they can be used in the designing encapsulation systems for delivery of bdellovibrios.


Assuntos
Bdellovibrio bacteriovorus/fisiologia , Bdellovibrio bacteriovorus/patogenicidade , Agentes de Controle Biológico/farmacologia , Pantoea/efeitos dos fármacos , Pantoea/fisiologia , Xanthomonas campestris/efeitos dos fármacos , Xanthomonas campestris/fisiologia , Antibiose , Biopolímeros/fisiologia , Técnicas de Cocultura/métodos , DNA Bacteriano , Interações Microbianas , RNA Ribossômico 16S
2.
J Gen Appl Microbiol ; 67(2): 59-66, 2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-33518552

RESUMO

Pantoea agglomerans YS19 is a dominant endophytic bacterium isolated from rice, which is capable of promoting host plant growth by nitrogen-fixing and phytohormone secreting. We previously found that the cytidine repressor (CytR) protein conducts the regulation of indole signal in YS19. Here, we compared the whole-cell protein of the wild type YS19 and the ΔcytR mutant and subsequently identified one differential protein as alkyl hydroperoxide reductase subunit C related to oxidative stress and sulfur starvation tolerance. It was tested that cytR had a positive effect on the survival of YS19 under the oxidative stress and sulfur starvation conditions and this effect was inhibited by indole. To further understand the functional mode of indole in this regulation, we cloned the cytR promoter region (PcytR) of YS19 and tested the effect of indole on PcytR using gfp as a reporter gene. It was found that PcytR can sense indole and significantly inhibit the expression of the downstream gene. This study provided a deeper understanding of the multiple function of cytR and expanded a new research direction of how indole participates in gene regulation.


Assuntos
Proteínas de Bactérias/metabolismo , Estresse Oxidativo/fisiologia , Pantoea/fisiologia , Proteínas Repressoras/metabolismo , Enxofre/metabolismo , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Indóis/farmacologia , Viabilidade Microbiana/efeitos dos fármacos , Mutação , Estresse Oxidativo/efeitos dos fármacos , Peroxirredoxinas/genética , Regiões Promotoras Genéticas , Proteínas Repressoras/genética
3.
Environ Microbiol ; 23(1): 36-50, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32686279

RESUMO

Phytophagous stink bugs typically harbor nutritional symbiotic bacteria in their midgut, to integrate their unbalanced diet. In the Pentatomidae, most symbionts are affiliated to the genus Pantoea, and are polyphyletic. This suggests a scenario of an ancestral establishment of symbiosis, followed by multiple symbiont replacement events by akin environmental bacteria in different host lineages. In this study, a novel Pantoeaspecies ('CandidatusPantoea persica') was characterized from the gut of the pentatomid Acrosternum arabicum, and shown to be highly abundant in a specific portion of the gut and necessary for the host development. The genome of the symbiont (2.9 Mb), while presenting putative host-supportive metabolic pathways, including those for amino acids and vitamin synthesis, showed a high level of pseudogenization, indicating ongoing genome reduction. Comparative analyses with other free-living and symbiotic Pantoea highlighted a convergent pattern of genome reduction in symbionts of pentatomids, putatively following the typical phases modelized in obligate nutritional symbionts of insects. Additionally, this system has distinctive traits, as hosts are closely related, and symbionts originated multiple independent times from closely related free-living bacteria, displaying convergent and independent conspicuous genome reduction. Due to such peculiarities, this may become an ideal model to study genome evolutionary processes in insect symbionts.


Assuntos
Genoma Bacteriano , Heterópteros/microbiologia , Pantoea/genética , Simbiose , Animais , Evolução Molecular , Heterópteros/fisiologia , Redes e Vias Metabólicas , Pantoea/classificação , Pantoea/isolamento & purificação , Pantoea/fisiologia , Filogenia
4.
Sci Rep ; 10(1): 18441, 2020 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-33116256

RESUMO

The brown marmorated stink bug Halyomorpha halys (Stål) is a globally invasive species that harbours the primary bacterial symbiont 'Candidatus Pantoea carbekii'. In this work, P. carbekii was used as another genetic marker to investigate the biodiversity and biogeographical patterns of this important pest, in native and newly invaded areas, especially in Italy. The correlation between the genetic structure of the symbiont and that of its host was studied through the analyses of one bacterial and one host marker, the putative pseudogene ΔybgF and the mitochondrial gene COI, respectively. As a result, five new P. carbekii haplotypes were identified, and an association pattern between host-symbiont haplotypes was observed. Host species showed higher haplotype diversity than symbiont, which can be expected in a long term host-symbiont association. Populations from the north-eastern Italy showed the highest values of genetic diversity for both markers, highlighting that this particular Italian area could be the result of multiple ongoing introductions. Moreover, some of the symbiont-host haplotypes observed were shared only by populations from north-eastern Italy and native areas, especially Japan, suggesting further introductions from this native country to Italy. Overall, our findings improve the understanding of the potential origin of multiple accidental introductions of H. halys in Italy.


Assuntos
Haplótipos , Heterópteros/genética , Heterópteros/microbiologia , Espécies Introduzidas , Simbiose/fisiologia , Animais , Itália , Pantoea/fisiologia
5.
Int J Mol Sci ; 21(17)2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32878176

RESUMO

The Gram-negative Pantoea eucrina D2 was isolated from the marine sponge Chondrosia reniformis. Sponges were collected in a shallow volcanic vents system in Ischia island (South Italy), influenced by CO2 emissions and lowered pH. The chemical diversity of the secondary metabolites produced by this strain, under different culture conditions, was explored by a combined approach including molecular networking, pure compound isolation and NMR spectroscopy. The metabolome of Pantoea cf. eucrina D2 yielded a very complex molecular network, allowing the annotation of several metabolites, among them two biosurfactant clusters: lipoamino acids and surfactins. The production of each class of metabolites was highly dependent on the culture conditions, in particular, the production of unusual surfactins derivatives was reported for the first time from this genus; interestingly the production of these metabolites only arises by utilizing inorganic nitrogen as a sole nitrogen source. Major components of the extract obtained under standard medium culture conditions were isolated and identified as N-lipoamino acids by a combination of 1D and 2D NMR spectroscopy and HRESI-MS analysis. Assessment of the antimicrobial activity of the pure compounds towards some human pathogens, indicated a moderate activity of leucine containing N-lipoamino acids towards Staphylococcus aureus, Staphylococcus epidermidis and a clinical isolate of the emerging food pathogen Listeria monocytogenes.


Assuntos
Antibacterianos/farmacologia , Meios de Cultura/farmacologia , Redes e Vias Metabólicas , Metaboloma/efeitos dos fármacos , Pantoea/fisiologia , Poríferos/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Ácidos/química , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Meios de Cultura/química , Humanos , Filogenia , Poríferos/fisiologia
6.
Lett Appl Microbiol ; 71(4): 330-336, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32506499

RESUMO

The deferred antagonism technique has been utilized for several decades for detecting antibiosis activity. Most protocols require the elimination of antibiotic-producing cells by exposing them to chloroform vapour, UV radiation or filter sterilizing the filtrate steps that require additional time and expense to complete. We provide a modified approach to current soft agar overlay practices, which involves addition of antibiotics to the soft agar overlay to inhibit growth of the producer but not the indicator strain. This technique can be used to reproducibly and efficiently screen for antibiotic production with ease. We demonstrate the effectiveness of this technique with three bacterial systems: inhibition of the bacterial spot of tomato pathogen, Xanthomonas euvesicatoria, by its pathogenic competitor Xanthomonas perforans; and inhibition of the fire blight pathogen, Erwinia amylovora, by Pantoea vagans C9-1 or Pseudomonas fluorescens A506. SIGNIFICANCE AND IMPACT OF THE STUDY: Deferred antagonism assays are used commonly to observe antibiotic production by micro-organisms. Killing or removing the producer cells prior to introduction of the indicator strain is a standard practice but requires additional time and special handling procedures. We evaluated a modification of the assay, where the overlay medium is amended with an antibiotic to which the indicator strain is resistant and the producer strain is sensitive. This modification obviates extra steps to kill the producer strain prior to overlaying with the indicator strain and provides a rapid, consistent and cost-effective method to detect antibiosis.


Assuntos
Antibiose , Erwinia amylovora/fisiologia , Técnicas Microbiológicas/métodos , Pantoea/fisiologia , Pseudomonas fluorescens/fisiologia , Xanthomonas/fisiologia , /microbiologia , Doenças das Plantas/microbiologia , Xanthomonas/crescimento & desenvolvimento
7.
J Appl Microbiol ; 129(4): 958-970, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32329126

RESUMO

AIMS: Pinus massoniana is one of the most widely distributed forest plants in China. In this study, we isolated a bacterial endophyte (designated FBS135) from apical buds and needles of P. massoniana. Investigations were performed to understand the effects of the strain on pine growth, its genomic features and the functions of the plasmids it carries. METHODS AND RESULTS: Based on its morphological features and 16S rRNA sequence, strain FBS135 was primarily identified as Pantoea eucalypti. We found that FBS135 not only promoted the growth of P. massoniana seedlings, but also significantly increased the survival rate of pine seedlings. The whole genome of FBS135 was sequenced, which revealed that the bacterium carries one chromosome and four plasmids. Its chromosome is 4 023 751 bp in size and contains dozens of genes involved in plant symbiosis. Curing one of the four plasmids, pPant1, resulted in a decrease in the size of the FBS135 colonies and the loss of the ability to synthesize yellow pigment, indicating that this plasmid may be very important for FBS135. CONCLUSIONS: Pantoea eucalypti FBS135 has a genomic basis to be implicated in plant-associated lifestyle and was established to have the capability to promote pine growth. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge, this is the first report that such a bacterial species, P. eucalypti, was isolated from pine trees and evidenced to have pine beneficial activities. Our results elucidate the ecological effects of endophytes on forest plants as well as endophyte-plant interaction mechanisms.


Assuntos
Genoma Bacteriano/genética , Pantoea/fisiologia , Pinus/crescimento & desenvolvimento , Pinus/microbiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , China , Endófitos/classificação , Endófitos/genética , Endófitos/fisiologia , Pantoea/classificação , Pantoea/genética , Plasmídeos/genética , Plasmídeos/metabolismo , RNA Ribossômico 16S/genética , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Simbiose
8.
J Appl Microbiol ; 129(3): 575-589, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32147927

RESUMO

OBJECTIVE: The present study was performed to examine the role of pqqE inhabiting rhizobacteria in organic acid production and relationship of the organic acids with phosphate solubilization by the bacteria in vitro as well as in vivo. METHODS AND RESULTS: The pqqE gene was PCR amplified and sequenced in genomic DNA of Pantoea sp. WP-5 and Pseudomonas sp. NN-4. Nucleotide sequence obtained from WP-5 and NN-4 showed maximum sequence similarity (88 and 89%, respectively) with the pqqE gene of Pseudomonas fluorescens strain CMR12a (KM251420). Deduced amino acid sequence from pqqE gene of Pseudomonas sp. NN-4 and Pantoea sp. WP-5 showed 75 and 93% similarity, respectively, with protein pyrroloquinoline quinone. Phosphate solubilization and acid production assay were quantified on spectrophotometer and high-profile liquid chromatograph, respectively, by each bacterial strain. Both strains produced organic acids such as acetic, citric, gluconic, succinic and malic acid and lowered the pH of Pikovskaya broth medium under laboratory conditions. Phosphate solubilization by Pantoea sp. WP-5 was 311 ± 4 and 204 ± 3 µg ml-1 in the culture medium supplemented with glucose and sucrose as carbon source, respectively. Pseudomonas sp. NN-4 solubilized 176 ± 3 and 298 ± 5 µg ml-1 phosphate in Pikovskaya broth medium under similar conditions. In field experiments conducted during two consecutive years, the concentration of acetic acid and gluconic acid was higher in root exudates of plants treated with Pantoea sp. WP-5 at 30% reduced doses of nitrogen (N)- and phosphorus (P)-based chemical fertilizers as compared to non-inoculated plants. Values of chlorophyll contents, crop growth rate, leaf area index, straw yield and P contents were recorded higher in plants inoculated with Pantoea sp. WP-5 and Pseudomonas sp. NN-4 as compared to non-inoculated control. Grain yield was increased by 10-12% due to inoculation with Pantoea sp. WP-5 and Pseudomonas sp. NN-4 over non-inoculated control in the field experiments. CONCLUSIONS: These results lead to the conclusions that the rhizobacteria inhabiting pqqE gene produced organic acids and solubilized the phosphate in vitro. On inoculation to wheat plants in field experiments, these strains produced the organic acids, solubilized the phosphate, and improved the P uptake and productivity of wheat. SIGNIFICANCE AND IMPACT OF THE STUDY: The Pantoea sp. WP-5 and Pseudomonas sp. NN-4 are the potential candidates for inoculation to wheat as phosphate solubilizer even with reduced chemical fertilizer dose. The inoculation of the strains may enhance grain yield and net income of the farmer even with less chemical fertilizer application. This practice will be helpfull inminimizing environmental pollution.


Assuntos
Proteínas de Bactérias/genética , Pantoea/fisiologia , Pseudomonas/fisiologia , Triticum/crescimento & desenvolvimento , Triticum/microbiologia , Ácidos/metabolismo , Proteínas de Bactérias/metabolismo , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/metabolismo , Fertilizantes/análise , Pantoea/genética , Pantoea/metabolismo , Fosfatos/metabolismo , Pseudomonas/genética , Pseudomonas/metabolismo , Solo/química , Microbiologia do Solo , Triticum/metabolismo
9.
Biomolecules ; 10(2)2020 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-32050703

RESUMO

Microbial co-culture or mixed fermentation proved to be an efficient strategy to expand chemical diversity by the induction of cryptic biosynthetic pathways, and in many cases led to the production of new antimicrobial agents. In the current study, we report a rare example of the induction of silent/cryptic bacterial biosynthetic pathway by the co-culture of Durum wheat plant roots-associated bacterium Pantoea aggolomerans and date palm leaves-derived fungus Penicillium citrinum. The initial co-culture indicated a clear fungal growth inhibition which was confirmed by the promising antifungal activity of the co-culture total extract against Pc. LC-HRMS chemical profiling demonstrated a huge suppression in the production of secondary metabolites (SMs) of axenic cultures of both species with the emergence of new metabolites which were dereplicated as a series of siderophores. Large-scale co-culture fermentation led to the isolation of two new pulicatin derivatives together with six known metabolites which were characterised using HRESIMS and NMR analyses. During the in vitro antimicrobial evaluation of the isolated compounds, pulicatin H (2) exhibited the strongest antifungal activity against Pc, followed by aeruginaldehyde (1) and pulicatin F (4), hence explaining the initial growth suppression of Pc in the co-culture environment.


Assuntos
Pantoea/química , Pantoea/metabolismo , Tiazolidinas/metabolismo , Antibacterianos , Anti-Infecciosos , Antifúngicos , Técnicas de Cocultura , Fermentação , Pantoea/fisiologia , Penicillium , Raízes de Plantas , Sideróforos
10.
Environ Microbiol ; 22(4): 1341-1355, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32077227

RESUMO

Numerous Pantoea strains are important because of the benefit they provide in the facilitation of plant growth. However, Pantoea have a high level of genotypic diversity and not much is understood regarding their ability to function in a plant beneficial manner. In the work reported here, the plant growth promotion activities and the genomic properties of the unusual Pantoea phytobeneficialis MSR2 are elaborated, emphasizing the genetic mechanisms involved in plant colonization and growth promotion. Detailed analysis revealed that strain MSR2 belongs to a rare group of Pantoea strains possessing an astonishing number of plant growth promotion genes, including those involved in nitrogen fixation, phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid deaminase activity, indoleacetic acid and cytokinin biosynthesis, and jasmonic acid metabolism. Moreover, the genome of this bacterium also contains genes involved in the metabolism of lignin and other plant cell wall compounds, quorum-sensing mechanisms, metabolism of plant root exudates, bacterial attachment to plant surfaces and resistance to plant defences. Importantly, the analysis revealed that most of these genes are present on accessory plasmids that are found within a small subset of Pantoea genomes, reinforcing the idea that Pantoea evolution is largely mediated by plasmids, providing new insights into the evolution of beneficial plant-associated Pantoea.


Assuntos
Pantoea/fisiologia , Reguladores de Crescimento de Plantas/fisiologia , Genoma de Planta , Ácidos Indolacéticos , Fixação de Nitrogênio , Pantoea/genética , Fosfatos/metabolismo , Desenvolvimento Vegetal , Raízes de Plantas/microbiologia
11.
J Chem Ecol ; 46(8): 782-792, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31956921

RESUMO

Epiphytic bacteria have been shown to affect the composition of volatiles released by plants and as a consequence the behavior of other organisms towards the plant, such as herbivores and/or pathogens. In this study, we explored the effects of inoculation with three bacterial strains, namely Pseudomonas syringae, Pantoea ananatis, and Pseudomonas putida, on the composition of leaf volatile organic compounds (VOCs) emitted by bean plants (Phaseolus vulgaris L.). In addition, we examined responses of the two-spotted spider mite (Tetranychus urticae) to VOCs by measuring leaf damage and oviposition of female adults after bacterial inoculation. Colonized bean plants emitted different VOCs depending on the bacterial inoculum. The quantities of volatiles 1-undecanol and (Z)-3-hexen-1-ol significantly increased after P. syringae inoculation, while methyl salicylate and anisole increased in response to P. ananatis. T. urticae females preferred control plants over plants inoculated with P. syringae or P. putida in olfactometer assays, while no particular preference was recorded in the presence of P. ananatis. Furthermore, leaf damage caused by spider mites was 3-fold lower in plants inoculated with P. syringae than in control plants and plants inoculated with P. ananatis. Subsequently, the number of eggs laid on leaves inoculated with P. syringae was significantly lower than on those inoculated with P. ananatis or on the control ones. Moreover, a significantly higher number of spider mites selected methyl salicylate odor source over 1-undecanol, in a two-choice bioassay. The results demonstrate the bacterial involvement in plant-arthropod interactions and suggest further investigation on the potential use of bacteria as biocontrol agents in agriculture.


Assuntos
Pantoea/fisiologia , Phaseolus/química , Pseudomonas putida/fisiologia , Pseudomonas syringae/fisiologia , Tetranychidae/fisiologia , Compostos Orgânicos Voláteis/metabolismo , Animais , Feminino , Oviposição , Folhas de Planta/química
12.
Ann Agric Environ Med ; 26(4): 644-655, 2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31885240

RESUMO

CASE DESCRIPTION: Five workers (2 males and 3 females) employed in a furniture factory located in eastern Poland developed hypersensitivity pneumonitis (HP) after the pine wood used for furniture production was replaced by birch wood. All of them reported onset of respiratory and general symptoms (cough, shortness of breath, general malaise) after inhalation exposure to birch dust, showed crackles at auscultation, ground-glass attenuations in HRCT examination, and lymphocytosis in the BAL examination. The diagnosis of acute HP was set in 4 persons and the diagnosis of subacute HP in one. IDENTIFICATION OF SPECIFIC ALLERGEN: Samples of birch wood associated with evoking disease symptoms were subjected to microbiological analysis with the conventional and molecular methods. Two bacterial isolates were found to occur in large quantities (of the order 108 CFU/g) in examined samples: Gram-negative bacterium of the species Pantoea agglomerans and a non-filamentous Gram-positive actinobacterium of the species Microbacterium barkeri. In the test for inhibition of leukocyte migration, 4 out of 5 examined patients showed a positive reaction in the presence of P. agglomerans and 2 in the presence of M. barkeri. Only one person showed the presence of precipitins to P. agglomerans and none to M. barkeri. In the inhalation challenge, which is the most relevant allergological test in the HP diagnostics, all patients reacted positively to P. agglomerans and only one to M. barkeri. The results indicate that P. agglomerans developing in birch wood was the main agent causing HP in the workers exposed to the inhalation of dust from this wood, while the etiologic role of M. barkeri is probably secondary. CONCLUSION: The results demonstrate that apart from fungi and filamentous actinobacteria, regarded until recently as causative agents of HP in woodworkers, Gram-negative bacteria and non-filamentous actinobacteria may also elicit disease symptoms in the workers processing wood infected with large amounts of these microorganisms. The results obtained also seem to indicate that cellular-mediated reactions are more significant for causing disease symptoms compared to those that are precipitin-mediated.


Assuntos
Actinobacteria/isolamento & purificação , Poluentes Ocupacionais do Ar/efeitos adversos , Alveolite Alérgica Extrínseca/microbiologia , Betula/microbiologia , Poeira/análise , Exposição por Inalação/efeitos adversos , Pantoea/isolamento & purificação , Actinobacteria/genética , Actinobacteria/fisiologia , Doença Aguda , Adulto , Poluentes Ocupacionais do Ar/análise , Alveolite Alérgica Extrínseca/etiologia , Feminino , Humanos , Exposição por Inalação/análise , Masculino , Microbacterium , Pessoa de Meia-Idade , Pantoea/genética , Pantoea/fisiologia , Polônia , Madeira/microbiologia
13.
Sci Rep ; 9(1): 16354, 2019 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-31704990

RESUMO

Biocontrol offers a promising alternative to synthetic fungicides for the control of a variety of pre- and post-harvest diseases of crops. Black rot, which is caused by the pathogenic fungus Ceratocytis fimbriata, is the most destructive post-harvest disease of sweet potato, but little is currently known about potential biocontrol agents for this fungus. Here, we isolated several microorganisms from the tuberous roots and shoots of field-grown sweet potato plants, and analyzed their ribosomal RNA gene sequences. The microorganisms belonging to the genus Pantoea made up a major portion of the microbes residing within the sweet potato plants, and fluorescence microscopy showed these microbes colonized the intercellular spaces of the vascular tissue in the sweet potato stems. Four P. dispersa strains strongly inhibited C. fimbriata mycelium growth and spore germination, and altered the morphology of the fungal hyphae. The detection of dead C. fimbriata cells using Evans blue staining suggested that these P. dispersa strains have fungicidal rather than fungistatic activity. Furthermore, P. dispersa strains significantly inhibited C. fimbriata growth on the leaves and tuberous roots of a susceptible sweet potato cultivar ("Yulmi"). These findings suggest that P. dispersa strains could inhibit black rot in sweet potato plants, highlighting their potential as biocontrol agents.


Assuntos
Ascomicetos/crescimento & desenvolvimento , Ipomoea batatas/imunologia , Pantoea/fisiologia , Controle Biológico de Vetores , Doenças das Plantas/prevenção & controle , Folhas de Planta/imunologia , Raízes de Plantas/imunologia , Resistência à Doença , Ipomoea batatas/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia
14.
Mol Plant Microbe Interact ; 32(12): 1581-1597, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31657672

RESUMO

Vascular wilt bacteria such as Pantoea stewartii, the causal agent of Stewart's bacterial wilt of maize (SW), are destructive pathogens that are difficult to control. These bacteria colonize the xylem, where they form biofilms that block sap flow leading to characteristic wilting symptoms. Heritable forms of SW resistance exist and are used in maize breeding programs but the underlying genes and mechanisms are mostly unknown. Here, we show that seedlings of maize inbred lines with pan1 mutations are highly resistant to SW. However, current evidence suggests that other genes introgressed along with pan1 are responsible for resistance. Genomic analyses of pan1 lines were used to identify candidate resistance genes. In-depth comparison of P. stewartii interaction with susceptible and resistant maize lines revealed an enhanced vascular defense response in pan1 lines characterized by accumulation of electron-dense materials in xylem conduits visible by electron microscopy. We propose that this vascular defense response restricts P. stewartii spread through the vasculature, reducing both systemic bacterial colonization of the xylem network and consequent wilting. Though apparently unrelated to the resistance phenotype of pan1 lines, we also demonstrate that the effector WtsE is essential for P. stewartii xylem dissemination, show evidence for a nutritional immunity response to P. stewartii that alters xylem sap composition, and present the first analysis of maize transcriptional responses to P. stewartii infection.


Assuntos
Resistência à Doença , Pantoea , Zea mays , Resistência à Doença/genética , Genoma de Planta/genética , Pantoea/fisiologia , Plântula/microbiologia , Xilema/microbiologia , Zea mays/genética , Zea mays/microbiologia
15.
Chemosphere ; 237: 124540, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549654

RESUMO

Lead can be immobilized in contaminated soils by phosphate rock (PR) amendment, but its efficiency is generally limited by low solubility of PR. Our study aimed to elucidate whether phosphate solubilizing bacteria (PSB) can promote Pb immobilization through PR solubilization. Results showed that P. ananatis HCR2 and B. thuringiensis GL-1 could effectively solubilize PR by producing citric, glucose, and α-Ketoglutaric acids. In broth assay, phosphate solubilized from PR by PSB rapidly reacted with Pb2+ and formed insoluble lead compounds, as confirmed by scanning electron microscope, energy dispersive X-ray, and X-ray photoelectron spectroscopy. Pot experiment using lettuce (Lactuca sativa L.) and diffusive gradients in thin films (DGT) verified the effectiveness of soil remediation using PR amendment and PSB inoculation, as plant shoot biomass and net photosynthetic rate as well as soil bioavailable phosphate concentration have significantly increased, while the phytoavailability of Pb, Cd, and Zn greatly reduced. This study suggested that PR amendment combined with PSB inoculation could be applied for remediation of agricultural fields contaminated with multiple heavy metals.


Assuntos
Recuperação e Remediação Ambiental/métodos , Chumbo/química , Fosfatos/química , Microbiologia do Solo , Poluentes do Solo/química , Bacillus thuringiensis/fisiologia , Disponibilidade Biológica , Chumbo/farmacocinética , Alface/efeitos dos fármacos , Alface/crescimento & desenvolvimento , Alface/fisiologia , Metais Pesados/análise , Metais Pesados/farmacocinética , Pantoea/fisiologia , Espectroscopia Fotoeletrônica , Fotossíntese/fisiologia , Brotos de Planta/crescimento & desenvolvimento , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/farmacocinética , Solubilidade , Espectrometria por Raios X
16.
Int J Mol Sci ; 20(16)2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31426312

RESUMO

In the arid region Bou-Saâda at the South of Algeria, durum wheat Triticum durum L. cv Waha production is severely threatened by abiotic stresses, mainly drought and salinity. Plant growth-promoting rhizobacteria (PGPR) hold promising prospects towards sustainable and environmentally-friendly agriculture. Using habitat-adapted symbiosis strategy, the PGPR Pantoea agglomerans strain Pa was recovered from wheat roots sampled in Bou-Saâda, conferred alleviation of salt stress in durum wheat plants and allowed considerable growth in this unhostile environment. Strain Pa showed growth up to 35 °C temperature, 5-10 pH range, and up to 30% polyethylene glycol (PEG), as well as 1 M salt concentration tolerance. Pa strain displayed pertinent plant growth promotion (PGP) features (direct and indirect) such as hormone auxin biosynthesis, production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and ammonia and phosphate solubilization. PGPR features were stable over wide salt concentrations (0-400 mM). Pa strain was also able to survive in seeds, in the non-sterile and sterile wheat rhizosphere, and was shown to have an endophytic life style. Phylogenomic analysis of strain Pa indicated that Pantoea genus suffers taxonomic imprecision which blurs species delimitation and may have impacted their practical use as biofertilizers. When applied to plants, strain Pa promoted considerable growth of wheat seedlings, high chlorophyll content, lower accumulation of proline, and favored K+ accumulation in the inoculated plants when compared to Na+ in control non-inoculated plants. Metabolomic profiling of strain Pa under one strain many compounds (OSMAC) conditions revealed a wide diversity of secondary metabolites (SM) with interesting salt stress alleviation and PGP activities. All these findings strongly promote the implementation of Pantoea agglomerans strain Pa as an efficient biofertilizer in wheat plants culture in arid and salinity-impacted regions.


Assuntos
Endófitos/fisiologia , Pantoea/fisiologia , Simbiose , Triticum/fisiologia , Secas , Endófitos/genética , Pantoea/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Raízes de Plantas/fisiologia , Rizosfera , Salinidade , Tolerância ao Sal , Metabolismo Secundário , Estresse Fisiológico , Triticum/crescimento & desenvolvimento , Triticum/microbiologia
17.
Syst Appl Microbiol ; 42(4): 488-494, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31204142

RESUMO

Four endophytic bacterial strains were isolated from root, stem and leaf of maize planted in different regions of northern China. The four strains possessed almost identical 16S rRNA gene sequences. However, REP-PCR fingerprint patterns discriminated that they were not from one clonal origin. Furthermore, the average nucleotide identity (ANI) values among them were higher than 95%, suggesting they all belong to one species. Based on 16S rRNA gene phylogeny, the four strains were clustered together with Pantoea rodasii LMG 26273T and Pantoea rwandensis LMG 26275T, but on a separate branch. Multilocus sequence analysis (MLSA) indicated that the four strains form a novel Pantoea species. Authenticity of the novel species was confirmed by ANI comparisons between strain 596T and its closest relatives, since obtained values were considerably below the proposed thresholds for the species delineation. The genome size of 596T was 5.1Mbp, comprising 4896 predicted genes with DNA G+C content of 57.8mol%. The respiratory quinone was ubiquinone-8 (Q-8) and the polar lipid profile consisted of phosphatidylethanolamin, diphosphatidylglycerol, phosphatidylglycerol, unidentified aminophospholipid and unidentified phospholipid. The major fatty acids of strain 596T were C16:0, summed feature 2 (C12:0 aldehyde), summed feature 3 (C16:1ω7c and/or C16:1ω6c) and summed feature 8 (C18:1ω7c and/or C18:1ω6c). Based on phylogenetic, genomic, phenotypic and chemotaxonomic data, the four isolates are considered to represent a novel species of the genus Pantoea, for which the name Pantoea endophytica sp. nov., is proposed, with 596T (=DSM 100,785T=CGMCC 1.15280T) as type strain.


Assuntos
Pantoea/classificação , Pantoea/fisiologia , Filogenia , Zea mays/microbiologia , China , DNA Bacteriano/genética , Endófitos , Ácidos Graxos/química , Genes Bacterianos/genética , Genes Essenciais/genética , Genoma Bacteriano/genética , Pantoea/química , Pantoea/genética , Fenótipo , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Especificidade da Espécie , Ubiquinona/química
18.
PLoS One ; 14(6): e0218102, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31170240

RESUMO

Artificial surfaces are routinely used instead of leaves to enable a reductionist approach in phyllosphere microbiology, the study of microorganisms residing on plant leaf surfaces. Commonly used artificial surfaces include, flat surfaces, such as metal and nutrient agar, and microstructured surfaces, such as isolate leaf cuticles or reconstituted leaf waxes. However, interest in replica leaf surfaces as an artificial surface is growing, as replica surfaces provide an improved representation of the complex topography of leaf surfaces. To date, leaf surfaces have predominantly been replicated for their superhydrophobic properties. In contrast, in this paper we investigated the potential of agarose, the elastomer polydimethylsiloxane (PDMS), and gelatin as replica leaf surface materials for phyllosphere microbiology studies. Using a test pattern of pillars, we investigated the ability to replicate microstructures into the materials, as well as the degradation characteristics of the materials in environmental conditions. Pillars produced in PDMS were measured to be within 10% of the mold master and remained stable throughout the degradation experiments. In agarose and gelatin the pillars deviated by more than 10% and degraded considerably within 48 hours in environmental conditions. Furthermore, we investigated the surface energy of the materials, an important property of a leaf surface, which influences resource availability and microorganism attachment. We found that the surface energy and bacterial viability on PDMS was comparable to isolated Citrus × aurantium and Populus × canescens leaf cuticles. Hence indicating that PDMS is the most suitable material for replica leaf surfaces. In summary, our experiments highlight the importance of considering the inherent material properties when selecting a replica leaf surface for phyllosphere microbiology studies. As demonstrated, a PDMS replica leaf offers a control surface that can be used for investigating microbe-microbe and microbe-plant interactions in the phyllosphere, which will enable mitigation strategies against pathogens to be developed.


Assuntos
Folhas de Planta/anatomia & histologia , Folhas de Planta/microbiologia , Animais , Gelatina , Processamento de Imagem Assistida por Computador , Viabilidade Microbiana , Pantoea/fisiologia , Reconhecimento Automatizado de Padrão , Propriedades de Superfície , Suínos
19.
PLoS One ; 14(6): e0218316, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31246972

RESUMO

Bacteria occupy heterogeneous environments, attaching and growing within pores in materials, living hosts, and matrices like soil. Systems that permit high-resolution visualization of dynamic bacterial processes within the physical confines of a realistic and tractable porous media environment are rare. Here we use microfluidics to replicate the grain shape and packing density of natural sands in a 2D platform to study the flow-induced spatial evolution of bacterial biofilms underground. We discover that initial bacterial dispersal and grain attachment is influenced by bacterial transport across pore space velocity gradients, a phenomenon otherwise known as rheotaxis. We find that gravity-driven flow conditions activate different bacterial cell-clustering phenotypes depending on the strain's ability to product extracellular polymeric substances (EPS). A wildtype, biofilm-producing bacteria formed compact, multicellular patches while an EPS-defective mutant displayed a linked-cell phenotype in the presence of flow. These phenotypes subsequently influenced the overall spatial distribution of cells across the porous media network as colonies grew and altered the fluid dynamics of their microenvironment.


Assuntos
Biofilmes , Hidrodinâmica , Microfluídica , Pantoea/fisiologia , Biopolímeros/metabolismo , Fluorescência , Microfluídica/instrumentação , Mutação/genética , Pantoea/crescimento & desenvolvimento , Porosidade , Pressão , Fatores de Tempo
20.
Plant Dis ; 103(5): 938-943, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30893026

RESUMO

Onion thrips (Thrips tabaci) is a major insect pest of onion and it has been identified as a likely vector of Pantoea agglomerans (bacterial stalk and leaf necrosis), a relatively new pathogen to Michigan's onion industry. Our objective was to develop an integrated insect and disease management program by examining the efficacy of bactericides and insecticides alone and in combination to limit bacterial stalk and leaf necrosis caused by P. agglomerans. We also examined the association of onion thrips and disease incidence in the field, because thrips are known to transmit this pathogen. In the pesticide trial, insecticides reduced both thrips abundance and bacterial stalk and leaf necrosis incidence whereas bactericides alone did not reduce disease severity. Positive correlations among thrips population density, numbers of thrips positive for P. agglomerans, and bacterial stalk and leaf necrosis incidence in onion fields were determined. This study suggests that onion thrips feeding can facilitate the development of bacterial stalk and leaf necrosis in Michigan's commercial onion fields, and results from the pesticide trials indicate that thrips feeding damage is positively correlated with disease incidence. Therefore, in order to reduce bacterial stalk and leaf necrosis incidence in onion, management efforts should include reducing onion thrips populations through the use of insecticides and other cultural practices.


Assuntos
Inseticidas , Pantoea , Doenças das Plantas , Tisanópteros , Animais , Michigan , Cebolas/microbiologia , Cebolas/parasitologia , Pantoea/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Tisanópteros/microbiologia , Tisanópteros/fisiologia
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