-
Molecules (Basel, Switzerland) Jan 2021The genus possesses ecological and metabolic diversities. A large number of silent biosynthetic gene clusters (BGCs) in the genome remain uncharacterized and represent...
The genus possesses ecological and metabolic diversities. A large number of silent biosynthetic gene clusters (BGCs) in the genome remain uncharacterized and represent a promising resource for new natural product discovery. However, exploitation of the metabolomic potential of is limited by the absence of efficient genetic manipulation tools. Here, we screened a bacteriophage recombinase system Redγ-BAS, which was functional for genome modification in the plant pathogen ATCC 10248. By using this recombineering tool, the constitutive promoters were precisely inserted in the genome, leading to activation of two silent nonribosomal peptide synthetase gene clusters ( and ) and production of corresponding new classes of lipopeptides, burriogladiodins A-H (-) and haereogladiodins A-B (-). Structure elucidation revealed an unnatural amino acid - dehydrobutyrine (Dhb) in - and an -Dhb in -. Notably, compounds - and feature an unusual threonine tag that is longer than the predicted collinearity assembly lines. The structural diversity of burriogladiodins was derived from the relaxed substrate specificity of the fifth adenylation domain as well as chain termination conducted by water or threonine. The recombinase-mediating genome editing system is not only applicable in but also possesses great potential for mining meaningful silent gene clusters from other species.
Topics: Biosynthetic Pathways; Burkholderia gladioli; Genome, Bacterial; Genomics; Lipopeptides; Multigene Family; Peptide Synthases; Promoter Regions, Genetic; Recombinases
PubMed: 33572733
DOI: 10.3390/molecules26030700 -
Molecular Microbiology Jun 2022Bacterial opportunistic pathogens make diverse secondary metabolites both in the natural environment and when causing infections, yet how these molecules mediate...
Bacterial opportunistic pathogens make diverse secondary metabolites both in the natural environment and when causing infections, yet how these molecules mediate microbial interactions and their consequences for antibiotic treatment are still poorly understood. Here, we explore the role of three redox-active secondary metabolites, pyocyanin, phenazine-1-carboxylic acid, and toxoflavin, as interspecies modulators of antibiotic resilience. We find that these molecules dramatically change susceptibility levels of diverse bacteria to clinical antibiotics. Pyocyanin and phenazine-1-carboxylic acid are made by Pseudomonas aeruginosa, while toxoflavin is made by Burkholderia gladioli, organisms that infect cystic fibrosis and other immunocompromised patients. All molecules alter the susceptibility profile of pathogenic species within the "Burkholderia cepacia complex" to different antibiotics, either antagonizing or potentiating their effects, depending on the drug's class. Defense responses regulated by the redox-sensitive transcription factor SoxR potentiate the antagonistic effects these metabolites have against fluoroquinolones, and the presence of genes encoding SoxR and the efflux systems it regulates can be used to predict how these metabolites will affect antibiotic susceptibility of different bacteria. Finally, we demonstrate that inclusion of secondary metabolites in standard protocols used to assess antibiotic resistance can dramatically alter the results, motivating the development of new tests for more accurate clinical assessment.
Topics: Anti-Bacterial Agents; Burkholderia cepacia complex; Humans; Phenazines; Pseudomonas aeruginosa; Pyocyanine; Pyrimidinones; Triazines
PubMed: 35510686
DOI: 10.1111/mmi.14915 -
Brazilian Journal of Microbiology :... Dec 2021The Burkholderia genus has high ecological and nutritional versatility, having species capable of causing diseases in animals, humans, and plants. During chronic...
The Burkholderia genus has high ecological and nutritional versatility, having species capable of causing diseases in animals, humans, and plants. During chronic infections in humans, biofilm formation is a characteristic often associated with strains from different species of this genus. However, there is still no information on the formation of biofilms by plant pathogenic strains of B. cenocepacia (Bce) lineages IIIA and IIIB and B. gladioli pv. alliicola (Bga), which are associated with onion bacterial scale rot in the semi-arid region of northeast Brazil. In this study, we performed an in vitro characterization of biofilm formation ability in different culture media by the phytopathogenic strains of Bce and Bga and investigated its relationship with swarming motility. Our results indicated the existence of an intraspecific variation in biofilm formation capacity in vitro by these bacteria and the existence of a negative correlation between swarming motility and biofilm formation for strains of Bce lineage IIIB. In addition, histopathological analyses performed using optical microscopy and scanning electron microscopy revealed the formation of biofilm in vivo by Bce strains in onion tissues.
Topics: Biofilms; Brazil; Burkholderia cenocepacia; Microscopy, Electron, Scanning; Onions; Plant Diseases
PubMed: 34351603
DOI: 10.1007/s42770-021-00564-6 -
Antimicrobial Agents and Chemotherapy Feb 2021The Gram-negative bacterial genus includes several hard-to-treat human pathogens: two biothreat species, (causing glanders) and (causing melioidosis), and the...
The Gram-negative bacterial genus includes several hard-to-treat human pathogens: two biothreat species, (causing glanders) and (causing melioidosis), and the complex (BCC) and , which cause chronic lung infections in persons with cystic fibrosis. All spp. possess an Ambler class A Pen β-lactamase, which confers resistance to β-lactams. The β-lactam-β-lactamase inhibitor combination sulbactam-durlobactam (SUL-DUR) is in clinical development for the treatment of infections. In this study, we evaluated SUL-DUR for and activity against clinical isolates. We measured MICs of SUL-DUR against BCC and ( = 150), ( = 30), and ( = 28), studied the kinetics of inhibition of the PenA1 β-lactamase from and the PenI β-lactamase from by durlobactam, tested for induction by SUL-DUR, and evaluated efficacy in a mouse model of melioidosis. SUL-DUR inhibited growth of 87.3% of the BCC and strains and 100% of the and strains at 4/4 μg/ml. Durlobactam potently inhibited PenA1 and PenI with second-order rate constant for inactivation () values of 3.9 × 10 M s and 2.6 × 10 M s and apparent () of 15 nM and 241 nM, respectively, by forming highly stable covalent complexes. Neither sulbactam, durlobactam, nor SUL-DUR increased production of PenA1. SUL-DUR demonstrated activity in a murine melioidosis model. Taken together, these data suggest that SUL-DUR may be useful as a treatment for infections.
Topics: Animals; Anti-Bacterial Agents; Burkholderia; Burkholderia mallei; Burkholderia pseudomallei; Glanders; Horses; Melioidosis; Mice; Sulbactam
PubMed: 33318017
DOI: 10.1128/AAC.01930-20 -
Genomics-based Sensitive and Specific Novel Primers for Simultaneous Detection of and in Rice Seeds.The Plant Pathology Journal Dec 2018Panicle blight and seed rot disease caused mainly by and is threatening rice cultivation worldwide. The bacteria have been reported as seed-borne pathogens from rice....
Panicle blight and seed rot disease caused mainly by and is threatening rice cultivation worldwide. The bacteria have been reported as seed-borne pathogens from rice. Accurate detection of both pathogens on the seeds is very important for limiting the disease dissemination. Novel primer pairs targeting specific molecular markers were developed for the robust detection of and . The designed primers were specific in detecting the target species with no apparent crossreactions with other related species at the expected product size. Both primer pairs displayed a high degree of sensitivity for detection of and separately in monoplex PCR or simultaneously in duplex PCR from both extracted gDNA and directly preheated bacterial cell suspensions. Limit of detection was as low as 0.1 ng of gDNA of both species and 3.86 × 10 cells for and 5.85 × 10 cells for . On inoculated rice seeds, the designed primers could separately or simultaneously detect and with a detection limit as low as 1.86 × 10 cells per rice seed for and 1.04 × 10 cells per rice seed of . The novel primers maybe valuable as a more sensitive, specific, and robust tool for the efficient simultaneous detection of and on rice seeds, which is important in combating rice panicle blight and seed rot by early detection and confirmation of the dissemination of pathogen-free rice seeds.
PubMed: 30588222
DOI: 10.5423/PPJ.OA.07.2018.0136 -
Applied and Environmental Microbiology May 2019Fungal infections not only cause extensive agricultural damage but also result in serious diseases in the immunodeficient populations of human beings. Moreover, the...
Fungal infections not only cause extensive agricultural damage but also result in serious diseases in the immunodeficient populations of human beings. Moreover, the increasing emergence of drug resistance has led to a decrease in the efficacy of current antifungals. Thus, screening of new antifungal agents is imperative in the fight against antifungal drug resistance. In this study, we show that an endophytic bacterium, HDXY-02, isolated from the medicinal plant , showed broad-spectrum antifungal activity against plant and human fungal pathogens. An antifungal ability assay indicated that the bioactive component was produced from strain HDXY-02 having an extracellular secreted component with a molecular weight lower than 1,000 Da. In addition, we found that this new antifungal could be produced effectively by liquid fermentation of HDXY-02. Furthermore, the purified component contributing to the antifungal activity was identified to be toxoflavin, a yellow compound possessing a pyrimido[5,4-e][1,2,4]triazine ring. bioactivity studies demonstrated that purified toxoflavin from HDXY-02 cultures had a significant antifungal activity against the human fungal pathogen , resulting in abolished germination of conidia. More importantly, the growth inhibition by toxoflavin was observed in both wild-type and drug-resistant mutants ( and non-) of Finally, an optimized protocol for the large-scale production of toxoflavin (1,533 mg/liter) has been developed. Taken together, our findings provide a promising biosynthetic resource for producing a new antifungal reagent, toxoflavin, from isolates of the endophytic bacterium Human fungal infections are a growing problem associated with increased morbidity and mortality. Moreover, a growing number of antifungal-resistant fungal isolates have been reported over the past decade. Thus, the need for novel antifungal agents is imperative. In this study, we show that an endophytic bacterium, , isolated from the medicinal plant , is able to abundantly secrete a compound, toxoflavin, which has a strong fungicidal activity not only against plant fungal pathogens but also against human fungal pathogens and , , and the model filamentous fungus More importantly, toxoflavin also displays an efficacious inhibitory effect against azole antifungal-resistant mutants of Consequently, our findings provide a promising approach to abundantly produce toxoflavin, which has novel broad-spectrum antifungal activity, especially against those currently problematic drug-resistant isolates.
Topics: Antifungal Agents; Burkholderia gladioli; Fungicides, Industrial; Lycoris; Pyrimidinones; Triazines
PubMed: 30824447
DOI: 10.1128/AEM.00106-19 -
Methods in Enzymology 2022There is a great discrepancy between the natural product output of cultured microorganisms and their bioinformatically predicted biosynthetic potential, such that most...
There is a great discrepancy between the natural product output of cultured microorganisms and their bioinformatically predicted biosynthetic potential, such that most of the molecular diversity contained within microbial reservoirs has yet to be discovered. One of the primary reasons is insufficient expression of natural product biosynthetic gene clusters (BGCs) under standard laboratory conditions. Several methods have been developed to increase production from such "cryptic" BGCs. Among these, we recently implemented mass spectrometry-guided transposon mutagenesis, a forward genetic screen in which mutants that exhibit stimulated biosynthesis of cryptic metabolites, as read out by mass spectrometry, are selected from a transposon mutant library. Herein, we use Burkholderia gladioli as an example and provide guidelines for generating transposon mutant libraries, measuring metabolomic inventories through mass spectrometry, performing comparative metabolomics to prioritize cryptic natural products from the mutant library, and isolating and characterizing novel natural products elicited through mutagenesis. Application of this approach will be useful in both accessing novel natural products from cryptic BGCs and identifying genes involved in their global regulation.
Topics: Biological Products; Mass Spectrometry; Metabolomics; Multigene Family; Mutagenesis
PubMed: 35379440
DOI: 10.1016/bs.mie.2021.11.020 -
Journal of Cystic Fibrosis : Official... Jul 2007The impact of infection with Burkholderia gladioli in cystic fibrosis, other chronic airway diseases and immunosuppressed patients is unknown.
BACKGROUND
The impact of infection with Burkholderia gladioli in cystic fibrosis, other chronic airway diseases and immunosuppressed patients is unknown.
METHODS
A six-year retrospective review of all patients with B. gladioli infection was performed in a tertiary referral center with cystic fibrosis and lung transplantation programs. In addition, a targeted survey of all 251 lung transplant recipients was performed. Available B. gladioli isolates were analyzed via pulsed field gel electrophoresis.
RESULTS
Thirty-five patients were culture positive for B. gladioli, including 33 CF patients. No bacteremia was identified. Isolates were available in 18 patients and all were genetically distinct. Two-thirds of these isolates were susceptible to usual anti-pseudomonal antibiotics. After acquisition, only 40% of CF patients were chronically infected (> or =2 positive cultures separated by at least 6 months). Chronic infection was associated with resistance to > or =2 antibiotic groups on initial culture and failure of eradication after antibiotic therapy. The impact of acquisition of B. gladioli infection in chronic infection was variable. Three CF patients with chronic infection underwent lung transplantation. One post-transplant patient developed a B. gladioli mediastinal abscess, which was treated successfully.
CONCLUSIONS
The majority of patients' culture positive for B. gladioli at our center have CF. B. gladioli infection is often transient and is compatible with satisfactory post-lung transplantation outcomes.
Topics: Adolescent; Adult; Burkholderia Infections; Burkholderia gladioli; Child; Cross Infection; Cystic Fibrosis; Electrophoresis, Gel, Pulsed-Field; Female; Follow-Up Studies; Humans; Incidence; Lung Transplantation; Male; Respiratory Care Units; Retrospective Studies; Time Factors; United States
PubMed: 17137846
DOI: 10.1016/j.jcf.2006.10.007 -
International Journal of Infectious... Aug 2022Burkholderia gladioli has been associated with infections in patients with cystic fibrosis, chronic granulomatous disease, and other immunocompromising conditions. The...
OBJECTIVES
Burkholderia gladioli has been associated with infections in patients with cystic fibrosis, chronic granulomatous disease, and other immunocompromising conditions. The aim of this study was to better depict the outbreak of healthcare-associated bacteremia caused by B. gladioli due to exposure to contaminated multidose vials with saline solutions.
METHODS
An environmental and epidemiologic investigation was conducted by the Infection Prevention and Control Team (IPCT) to identify the source of the outbreak in three Croatian hospitals.
RESULTS
During a 3-month period, 13 B. gladioli bacteremia episodes were identified in 10 patients in three Croatian hospitals. At the time of the outbreak, all three hospitals used saline products from the same manufacturer. Two 100-ml multidose vials with saline solutions and needleless dispensing pins were positive for B. gladioli. All 13 bacteremia isolates and two isolates from the saline showed the same antimicrobial susceptibility patterns and pulsed-field gel electrophoresis profile, demonstrating clonal relatedness.
CONCLUSION
When an environmental pathogen causes an outbreak, contamination of intravenous products must be considered. Close communication between the local IPCT and the National Hospital Infection Control Advisory Committee is essential to conduct a prompt and thorough investigation and find the source of the outbreak.
Topics: Bacteremia; Burkholderia Infections; Burkholderia gladioli; Croatia; Cross Infection; Delivery of Health Care; Disease Outbreaks; Hospitals; Humans; Saline Solution
PubMed: 35562041
DOI: 10.1016/j.ijid.2022.05.012 -
Chembiochem : a European Journal of... Oct 2021Soft rot disease of edible mushrooms leads to rapid degeneration of fungal tissue and thus severely affects farming productivity worldwide. The bacterial mushroom...
Soft rot disease of edible mushrooms leads to rapid degeneration of fungal tissue and thus severely affects farming productivity worldwide. The bacterial mushroom pathogen Burkholderia gladioli pv. agaricicola has been identified as the cause. Yet, little is known about the molecular basis of the infection, the spatial distribution and the biological role of antifungal agents and toxins involved in this infectious disease. We combine genome mining, metabolic profiling, MALDI-Imaging and UV Raman spectroscopy, to detect, identify and visualize a complex of chemical mediators and toxins produced by the pathogen during the infection process, including toxoflavin, caryoynencin, and sinapigladioside. Furthermore, targeted gene knockouts and in vitro assays link antifungal agents to prevalent symptoms of soft rot, mushroom browning, and impaired mycelium growth. Comparisons of related pathogenic, mutualistic and environmental Burkholderia spp. indicate that the arsenal of antifungal agents may have paved the way for ancestral bacteria to colonize niches where frequent, antagonistic interactions with fungi occur. Our findings not only demonstrate the power of label-free, in vivo detection of polyyne virulence factors by Raman imaging, but may also inspire new approaches to disease control.
Topics: Agaricales; Antifungal Agents; Bacterial Toxins; Burkholderia gladioli; Microbial Sensitivity Tests; Molecular Imaging; Plant Diseases
PubMed: 34232540
DOI: 10.1002/cbic.202100330