-
PloS One 2021Pantoea agglomerans is a Gram-negative facultative anaerobic bacillus causing a wide range of opportunistic infections in humans including septicemia, pneumonia, septic...
Pantoea agglomerans is a Gram-negative facultative anaerobic bacillus causing a wide range of opportunistic infections in humans including septicemia, pneumonia, septic arthritis, wound infections and meningitis. To date, the determinants of virulence, antibiotic resistance, metabolic features conferring survival and host-associated pathogenic potential of this bacterium remain largely underexplored. In this study, we sequenced and assembled the whole-genome of P. agglomerans KM1 isolated from kimchi in South Korea. The genome contained one circular chromosome of 4,039,945 bp, 3 mega plasmids, and 2 prophages. The phage-derived genes encoded integrase, lysozyme and terminase. Six CRISPR loci were identified within the bacterial chromosome. Further in-depth analysis showed that the genome contained 13 antibiotic resistance genes conferring resistance to clinically important antibiotics such as penicillin G, bacitracin, rifampicin, vancomycin, and fosfomycin. Genes involved in adaptations to environmental stress were also identified which included factors providing resistance to osmotic lysis, oxidative stress, as well as heat and cold shock. The genomic analysis of virulence factors led to identification of a type VI secretion system, hemolysin, filamentous hemagglutinin, and genes involved in iron uptake and sequestration. Finally, the data provided here show that, the KM1 isolate exerted strong immunostimulatory properties on RAW 264.7 macrophages in vitro. Stimulated cells produced Nitric Oxide (NO) and pro-inflammatory cytokines TNF-α, IL-6 and the anti-inflammatory cytokine IL-10. The upstream signaling for production of TNF-α, IL-6, IL-10, and NO depended on TLR4 and TLR1/2. While production of TNF-α, IL-6 and NO involved solely activation of the NF-κB, IL-10 secretion was largely dependent on NF-κB and to a lesser extent on MAPK Kinases. Taken together, the analysis of the whole-genome and immunostimulatory properties provided in-depth characterization of the P. agglomerans KM1 isolate shedding a new light on determinants of virulence that drive its interactions with the environment, other microorganisms and eukaryotic hosts.
Topics: Animals; Anti-Bacterial Agents; Bacterial Typing Techniques; Cytokines; Drug Resistance, Microbial; Enterobacteriaceae Infections; Genomics; Humans; Macrophages; Mice; NF-kappa B; Pantoea; Phylogeny; Plant Diseases; Plasmids; Prophages; RAW 264.7 Cells; Virulence; Virulence Factors
PubMed: 33406073
DOI: 10.1371/journal.pone.0239792 -
Molecular Plant Pathology Oct 2021The endophytic bacterium Pantoea agglomerans DAPP-PG 734 was previously isolated from olive knots caused by infection with Pseudomonas savastanoi pv. savastanoi DAPP-PG...
Synergistic interaction between the type III secretion system of the endophytic bacterium Pantoea agglomerans DAPP-PG 734 and the virulence of the causal agent of olive knot Pseudomonas savastanoi pv. savastanoi DAPP-PG 722.
The endophytic bacterium Pantoea agglomerans DAPP-PG 734 was previously isolated from olive knots caused by infection with Pseudomonas savastanoi pv. savastanoi DAPP-PG 722. Whole-genome analysis of this P. agglomerans strain revealed the presence of a Hypersensitive response and pathogenicity (Hrp) type III secretion system (T3SS). To assess the role of the P. agglomerans T3SS in the interaction with P. savastanoi pv. savastanoi, we generated independent knockout mutants in three Hrp genes of the P. agglomerans DAPP-PG 734 T3SS (hrpJ, hrpN, and hrpY). In contrast to the wildtype control, all three mutants failed to cause a hypersensitive response when infiltrated in tobacco leaves, suggesting that P. agglomerans T3SS is functional and injects effector proteins in plant cells. In contrast to P. savastanoi pv. savastanoi DAPP-PG 722, the wildtype strain P. agglomerans DAPP-PG 734 and its Hrp T3SS mutants did not cause olive knot disease in 1-year-old olive plants. Coinoculation of P. savastanoi pv. savastanoi with P. agglomerans wildtype strains did not significantly change the knot size, while the DAPP-PG 734 hrpY mutant induced a significant decrease in knot size, which could be complemented by providing hrpY on a plasmid. By epifluorescence microscopy and confocal laser scanning microscopy, we found that the localization patterns in knots were nonoverlapping for P. savastanoi pv. savastanoi and P. agglomerans when coinoculated. Our results suggest that suppression of olive plant defences mediated by the Hrp T3SS of P. agglomerans DAPP-PG 734 positively impacts the virulence of P. savastanoi pv. savastanoi DAPP-PG 722.
Topics: Olea; Pantoea; Piperazines; Plant Diseases; Pseudomonas; Type III Secretion Systems; Virulence
PubMed: 34268839
DOI: 10.1111/mpp.13105 -
Frontiers in Microbiology 2023The fermentative production of auxin/indole 3-acetate (IAA) using selected strains can be a promising approach to developing novel plant biostimulants for agriculture...
INTRODUCTION
The fermentative production of auxin/indole 3-acetate (IAA) using selected strains can be a promising approach to developing novel plant biostimulants for agriculture use.
METHODS
By integrating metabolomics and fermentation technologies, this study aimed to define the optimal culture conditions to obtain auxin/IAA-enriched plant postbiotics using strain C1. Metabolomics analysis allowed us to demonstrate that the production of a selected.
RESULTS AND DISCUSSION
Array of compounds with plant growth-promoting- (IAA and hypoxanthine) and biocontrol activity (NS-5, cyclohexanone, homo-L-arginine, methyl hexadecenoic acid, and indole-3-carbinol) can be stimulated by cultivating this strain on minimal saline medium amended with sucrose as a carbon source. We applied a three-level-two-factor central composite design (CCD) based response surface methodology (RSM) to explore the impact of the independent variables (rotation speed and medium liquid-to-flask volume ratio) on the production of IAA and IAA precursors. The ANOVA component of the CCD indicated that all the process-independent variables investigated significantly impacted the auxin/IAA production by train C1. The optimum values of variables were a rotation speed of 180 rpm and a medium liquid-to-flask volume ratio of 1:10. Using the CCD-RSM method, we obtained a maximum indole auxin production of 208.3 ± 0.4 mg IAA/L, which was a 40% increase compared to the growth conditions used in previous studies. Targeted metabolomics allowed us to demonstrate that the IAA product selectivity and the accumulation of the IAA precursor indole-3-pyruvic acid were significantly affected by the increase in the rotation speed and the aeration efficiency.
PubMed: 36970660
DOI: 10.3389/fmicb.2023.1022248 -
Journal of Microbiology and... May 2021Levan is an industrially important, functional biopolymer with considerable applications in the food and pharmaceutical fields owing to its safety and biocompatibility....
Levan is an industrially important, functional biopolymer with considerable applications in the food and pharmaceutical fields owing to its safety and biocompatibility. Here, levan-type exopolysaccharide produced by Pantoea agglomerans ZMR7 was purified by cold ethanol precipitation and characterized using TLC, FTIR, H, and C NMR spectroscopy. The maximum production of levan (28.4 g/l) was achieved when sucrose and ammonium chloride were used as carbon and nitrogen sources, respectively, at 35°C and an initial pH of 8.0. Some biomedical applications of levan like antitumor, antiparasitic, and antioxidant activities were investigated in vitro. The results revealed the ability of levan at different concentrations to decrease the viability of rhabdomyosarcoma and breast cancer cells compared with untreated cancer cells. Levan appeared also to have high antiparasitic activity against the promastigote of . Furthermore, levan had strong DPPH radical scavenging (antioxidant) activity. These findings suggest that levan produced by ZMR7 can serve as a natural biopolymer candidate for the pharmaceutical and medical fields.
Topics: Antineoplastic Agents; Antioxidants; Antiparasitic Agents; Cell Line, Tumor; Cell Proliferation; Culture Media; Fructans; Humans; Leishmania tropica; Pantoea; Polysaccharides, Bacterial
PubMed: 33820887
DOI: 10.4014/jmb.2101.01025 -
Microorganisms Aug 2021The bacterial genus has been widely evaluated as promising bacteria to increase phosphorus (P) availability in soil. The aim of this study was to characterize the...
The bacterial genus has been widely evaluated as promising bacteria to increase phosphorus (P) availability in soil. The aim of this study was to characterize the phosphate solubilizing (PS) activity of a strain and to evaluate the impact of its application in a semi-arid soil on phosphate availability and structure of the bacterial communities as a whole. An incubation experiment under close-to-natural soil environmental conditions was conducted for 15 days at 30 °C. High-throughput sequencing of the bacterial 16S rRNA gene was used to characterize and to compare the bacterial community structure of -inoculated soil with non-inoculated control. Furthermore, a qPCR-based method was developed for detection and quantification of the functional genes related to the expression of mineral phosphate solubilization (MPS) phenotype in . The results showed that in vitro solubilization of Ca(PO) by strain was very efficient (980 mg/L), and it was associated with a drop in pH due to the secretion of gluconic acid; these changes were concomitant with the detection of and genes. Moreover, inoculum application significantly increased the content of available P in semi-arid soil by 69%. Metagenomic analyses showed that treatment modified the overall edaphic bacterial community, significantly impacting its structure and composition. In particular, during inoculation the relative abundance of bacteria belonging to Firmicutes (mainly class) significantly increased, whereas the abundance of Actinobacteria together with Acidobacteria and Chloroflexi phyla decreased. Furthermore, genera known for their phosphate solubilizing activity, such as , , , and were exclusively detected in -treated soil. Pearson's correlation analysis revealed that changes in soil bacterial community composition were closely affected by soil characteristics, such as pH and available P. This study explores the effect of the inoculation of on the bacterial community structure of a semi-arid soil. The effectiveness in improving the phosphate availability and modification in soil bacterial community suggested that represent a promising environmental-friendly biofertilizer in arid and semi-arid ecosystems.
PubMed: 34442740
DOI: 10.3390/microorganisms9081661 -
PloS One 2019The Enterobacterial genus Pantoea contains both free-living and host-associating species, with considerable debate as to whether documented reports of human infections...
The Enterobacterial genus Pantoea contains both free-living and host-associating species, with considerable debate as to whether documented reports of human infections by members of this species group are accurate. MALDI-TOF-based identification methods are commonly used in clinical laboratories as a rapid means of identification, but its reliability for identification of Pantoea species is unclear. In this study, we carried out cpn60-based molecular typing of 54 clinical isolates that had been identified as Pantoea using MALDI-TOF and other clinical typing methods. We found that 24% had been misidentified, and were actually strains of Citrobacter, Enterobacter, Kosakonia, Klebsiella, Pseudocitrobacter, members of the newly described Erwinia gerundensis, and even several unclassified members of the Enterobacteriaceae. The 40 clinical strains that were confirmed to be Pantoea were identified as Pantoea agglomerans, Pantoea allii, Pantoea dispersa, Pantoea eucalypti, and Pantoea septica as well as the proposed species group, Pantoea latae. Some species groups considered largely environmental or plant-associated, such as P. allii and P. eucalypti were also among clinical specimens. Our results indicate that MALDI-TOF-based identification methods may misidentify strains of the Enterobacteriaceae as Pantoea.
Topics: Bacterial Typing Techniques; Diagnostic Errors; Enterobacteriaceae Infections; Humans; Pantoea; Phylogeny; Plants; Reproducibility of Results; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
PubMed: 31682625
DOI: 10.1371/journal.pone.0224731 -
Plant Disease Sep 2023Schisandra chinensis (Turcz.) Baill is a perennial liana, which is widely cultivated and used in China. In August 2022, Schisandra chinensis leaves with small light...
Schisandra chinensis (Turcz.) Baill is a perennial liana, which is widely cultivated and used in China. In August 2022, Schisandra chinensis leaves with small light brown spots were found on plants growing in Fusong (127°28'E, 42°33'N) of China. There was 15% disease incidence and 50% disease severity of Schisandra chinensis in 2-ha fields of S. chinensis. As the disease progressed, the spots become darker and form round or irregular concentric circles. Leaves with brown spot symptoms were collected from the field. Leaf pieces (5 mm × 5 mm) were excised from lesion margins, surface disinfected with 75% ethanol for 1 min, followed by 1.5% sodium hypochlorite for 3 min, and incubated on Luria Bertani (LB) solid medium at 28°C for 24 hours. Eight cultures were isolated, and representative single colony (XWWZH) was selected from the pure cultures according to colony characteristics for observation The purified colonies were round, yellow, and slimy, cells were straight rod-shaped (0.40 to 0.52 × 1.12 to 1.69 µm) were observed. The isolate was Gram negative. It was positive for methyl red reaction, lysine decarboxylase reaction, gelatin hydrolysis reactionand sucrose utilization. It was negative for indole reaction and produced H2S. The bacterium was preliminarily identified as Pantoea agglomerans based on morphological and biochemical tests (Baird et al. 2007). The 16S rDNA and a portion of rpoB of strain XWWZH were amplified and sequenced. The sequences were submitted to GenBank. (Accession OP763753 and OQ813505, respectively). Phylogenetic trees were constructed based on the 16S rDNA and rpoB gene sequences. The sequences of strain XWWZH clustered with strains P. agglomerans deposited in GenBank. The pathogenicity was verified with non-wounded S. chinensis seedlings by punching holes with sterile needles and injecting a solution of 1 × 108 CFU/ml solution. Sterile ddH2O was injected in the control experiment. The inoculated seedlings were incubated in a greenhouse at 25°C with a relative humidity of 65 to 70%. Five to eight days after inoculation, inoculated leaves, exhibited symptoms which were morphologically identical to those of the originally infected leaves whereas control plants remained asymptomatic. The pathogenicity assays were repeated twice with the same results. The re-isolated pathogen had the same morphology and DNA sequences as the original isolate obtained from the field samples, completing Koch's postulates. Strains of P. agglomerans have been reported to severely infect many plants (Ren et al.2008; Lee et al. 2010; Yang et al. 2011; Guo et al. 2019; Gao et al, 2022), but to the best of our knowledge, this is the first report of a strain of P. agglomerans causing leaf blight on Schisandra chinensis in China. The identification of leaf blight caused by P. agglomerans will enable farmers to prevent and manage it ahead of time to reduce losses.
PubMed: 37729653
DOI: 10.1094/PDIS-07-23-1258-PDN -
Plant Disease Apr 2022Onion is among the most consumed vegetables in Uruguay, grown in the northwestern and southern regions of the country. The onion supply presents interannual variations...
Onion is among the most consumed vegetables in Uruguay, grown in the northwestern and southern regions of the country. The onion supply presents interannual variations associated with significant postharvest losses, mainly caused by bacterial rots. Besides bulb rotting, onion leaf lesions as well as infections on seed-stalks during seed production may be devastating for some varieties under conducive conditions. This research aimed to identify the causal agents of bulb rots and leaf blight of onion crops in Uruguay. Symptomatic bulbs, seeds-stalks, and leaves were collected from commercial fields from 2015 to 2020. Bacterial colonies were isolated and identified at genera level using physiological tests and 16S rRNA gene sequence analysis. A collection of 59 spp. isolates was obtained (11 from bulbs and 48 from leaves and seeds-stalks). Multilocus sequence analysis using four housekeeping genes (, , , and ) allowed the assignment of the isolates to five species: , , , , and The last two species were not previously reported as onion pathogens elsewhere. The ability to cause disease symptoms was tested by leaf inoculation and red onion scale assays. isolates showed the highest aggressiveness in both assays. Specific isolates from (MAI 6022), (MAI 6036), (MAI 6050), and sp. (MAI 6049) ranked second in aggressiveness on onion leaves, whereas only three isolates belonging to (MAI 6036 and MAI 6058) and (MAI 6045) exhibited the same scale-clearing phenotype as . Leaf inoculation assays were also performed on a set of eight onion cultivars and breeding lines. Overall, MAI 6032 showed the highest aggressiveness in all tested cultivars, followed by MAI 6036. The presence of new reported bacterial species leads to complex disease management and highlights the need for further studies on virulence factors and the epidemiology of these pathogens.
Topics: Crops, Agricultural; Eucalyptus; Onions; Pantoea; Phylogeny; Plant Breeding; Plant Diseases; RNA, Ribosomal, 16S; Uruguay
PubMed: 34818920
DOI: 10.1094/PDIS-06-21-1140-RE -
Microorganisms Jan 2020Distinctive strains of are used as soil inoculants for their ability to promote plant growth. strain C1, previously isolated from the phyllosphere of lettuce, can...
Distinctive strains of are used as soil inoculants for their ability to promote plant growth. strain C1, previously isolated from the phyllosphere of lettuce, can produce indole-3-acetic acid (IAA), solubilize phosphate, and inhibit plant pathogens, such as . In this paper, the complete genome sequence of strain C1 is reported. In addition, experimental evidence is provided on how the strain tolerates arsenate As (V) up to 100 mM, and on how secreted metabolites like IAA and siderophores act as biostimulants in tomato cuttings. The strain has a circular chromosome and two prophages for a total genome of 4,846,925-bp, with a DNA G+C content of 55.2%. Genes related to plant growth promotion and biocontrol activity, such as those associated with IAA and spermidine synthesis, solubilization of inorganic phosphate, acquisition of ferrous iron, and production of volatile organic compounds, siderophores and GABA, were found in the genome of strain C1. Genome analysis also provided better understanding of the mechanisms underlying strain resistance to multiple toxic heavy metals and transmission of these genes by horizontal gene transfer. Findings suggested that strain C1 exhibits high biotechnological potential as plant growth-promoting bacterium in heavy metal polluted soils.
PubMed: 31979031
DOI: 10.3390/microorganisms8020153 -
Microbial Cell Factories Mar 2023The lipopeptide herbicolin A (HA) secreted by the biocontrol agent Pantoea agglomerans ZJU23 is a promising antifungal drug to combat fungal pathogens by targeting lipid...
BACKGROUND
The lipopeptide herbicolin A (HA) secreted by the biocontrol agent Pantoea agglomerans ZJU23 is a promising antifungal drug to combat fungal pathogens by targeting lipid rafts, both in agricultural and clinical settings. Improvement of HA production would be of great significance in promoting its commercialization. This study aims to enhance the HA production in ZJU23 by combining fermentation optimization and strain engineering.
RESULTS
Based on the results in the single-factor experiments, corn steep liquor, temperature and initial pH were identified as the significant affecting factors by the Plackett-Burman design. The fermentation medium and conditions were further optimized using the Box-Behnken response surface method, and the HA production of the wild type strain ZJU23 was improved from ~ 87 mg/mL in King's B medium to ~ 211 mg/mL in HA induction (HAI) medium. A transposon library was constructed in ZJU23 to screen for mutants with higher HA production, and two transcriptional repressors for HA biosynthesis, LrhA and PurR, were identified. Disruption of the LrhA gene led to increased mRNA expression of HA biosynthetic genes, and subsequently improved about twofold HA production. Finally, the HA production reached ~ 471 mg/mL in the ΔLrhA mutant under optimized fermentation conditions, which is about 5.4 times higher than before (~ 87 mg/mL). The bacterial suspension of the ΔLrhA mutant fermented in HAI medium significantly enhanced its biocontrol efficacy against gray mold disease and Fusarium crown rot of wheat, showing equivalent control efficacies as the chemical fungicides used in this study. Furthermore, HA was effective against fungicide resistant Botrytis cinerea. Increased HA production substantially improved the control efficacy against gray mold disease caused by a pyrimethanil resistant strain.
CONCLUSIONS
This study reveals that the transcriptional repressor LrhA negatively regulates HA biosynthesis and the defined HAI medium is suitable for HA production. These findings provide an extended basis for large-scale production of HA and promote biofungicide development based on ZJU23 and HA in the future.
Topics: Pantoea; Fermentation; Genetic Engineering; Antifungal Agents; Biological Control Agents; Temperature; Hydrogen-Ion Concentration; Gene Expression Regulation, Bacterial; Culture Media; Bioreactors; Regression Analysis; Analysis of Variance; Reproducibility of Results; Repressor Proteins; Mycoses; Crops, Agricultural; Plant Diseases; Humans; Animals
PubMed: 36915090
DOI: 10.1186/s12934-023-02051-z