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Molecular Plant-microbe Interactions :... Mar 2024Burkholderia gladioli pv. alliicola, B.cepacia, and B. orbicola are common bacterial pathogens of onion. Onions produce organosulfur thiosulfinate defensive compounds...
Burkholderia gladioli pv. alliicola, B.cepacia, and B. orbicola are common bacterial pathogens of onion. Onions produce organosulfur thiosulfinate defensive compounds after cellular decompartmentalization. Using whole genome sequencing and in silico analysis, we identified putative thiosulfinate tolerance gene (TTG) clusters in multiple onion-associated Burkholderia species similar to those characterized in other Allium-associated bacterial endophytes and pathogens. Sequence analysis revealed the presence of three Burkholderia TTG cluster types with both Type A and Type B being broadly distributed in B. gladioli, B. cepacia, and B. orbicola in both the chromosome and plasmids. Based on isolate natural variation and generation of isogenic strains, we determined the in vitro and in vivo contribution of TTG clusters in B. gladioli, B. cepacia, and B. orbicola. The Burkholderia TTG clusters contributed to enhanced allicin tolerance and improved growth in filtered onion extract by all three species. TTG clusters also made clear contributions to B. gladioli foliar necrosis symptoms and bacterial populations. Surprisingly, the TTG cluster did not contribute to bacterial populations in onion bulb scales by these three species. Based on our findings, we hypothesize onion-associated Burkholderia may evade or inhibit the production of thiosulfinates in onion bulb tissues.
PubMed: 38489400
DOI: 10.1094/MPMI-01-24-0005-R -
Comparative Medicine Feb 2024
PubMed: 38438126
DOI: 10.30802/AALAS-CM-24-000012 -
Chemical Science Feb 2024Foodborne pathogens pose a serious risk to human health, and the simple and rapid detection of such bacteria in complex food matrices remains challenging. Herein, we...
Foodborne pathogens pose a serious risk to human health, and the simple and rapid detection of such bacteria in complex food matrices remains challenging. Herein, we present the selection and characterization of a novel RNA-cleaving fluorogenic DNAzyme, named RFD-BC1, with exceptional specificity for (), a pathogen strongly associated with fatal food poisoning cases. RFD-BC1 was activated by a protein secreted specifically by whole viable and displayed an optimum pH distinct from the selection pH, with a rate constant of approximately 0.01 min at pH 5.0. Leveraging this newly discovered DNAzyme, we developed a novel system, termed DNAzymes-in-droplets (DID), that integrates droplet microfluidics to achieve the rapid and selective detection of live with single-cell sensitivity. We believe that the approach described herein holds promise for combating specific bacterial pathogens in food samples, offering significant potential for broader applications in food safety and public health.
PubMed: 38404397
DOI: 10.1039/d3sc05874c -
Journal of the American Chemical Society Mar 2024Microorganisms are remarkable chemists capable of assembling complex molecular architectures that penetrate cells and bind biomolecular targets with exquisite...
Microorganisms are remarkable chemists capable of assembling complex molecular architectures that penetrate cells and bind biomolecular targets with exquisite selectivity. Consequently, microbial natural products have wide-ranging applications in medicine and agriculture. How the "blind watchmaker" of evolution creates skeletal diversity is a key question in natural products research. Comparative analysis of biosynthetic pathways to structurally related metabolites is an insightful approach to addressing this. Here, we report comparative biosynthetic investigations of gladiolin, a polyketide antibiotic from with promising activity against multidrug-resistant , and etnangien, a structurally related antibiotic produced by . Although these metabolites have very similar macrolide cores, their C21 side chains differ significantly in both length and degree of saturation. Surprisingly, the -acyltransferase polyketide synthases (PKSs) that assemble these antibiotics are almost identical, raising intriguing questions about mechanisms underlying structural diversification in this important class of biosynthetic assembly line. reconstitution of key biosynthetic transformations using simplified substrate analogues, combined with gene deletion and complementation experiments, enabled us to elucidate the origin of all the structural differences in the C21 side chains of gladiolin and etnangien. The more saturated gladiolin side chain arises from a -acting enoylreductase (ER) domain in module 1 and in recruitment of a standalone ER to module 5 of the PKS. Remarkably, module 5 of the gladiolin PKS is intrinsically iterative in the absence of the standalone ER, accounting for the longer side chain in etnangien. These findings have important implications for biosynthetic engineering approaches to the creation of novel polyketide skeletons.
Topics: Polyketide Synthases; Acyltransferases; Anti-Bacterial Agents; Polyketides; Biological Products; Thiophenes; Sulfonamides; Macrolides; Polyenes; Imidazoles
PubMed: 38389455
DOI: 10.1021/jacs.3c13667 -
Microbiology Spectrum Apr 2024Fruit bodies (sporocarps) of wild mushrooms growing in natural environments play a substantial role in the preservation of microbial communities, for example, clinical...
Fruit bodies (sporocarps) of wild mushrooms growing in natural environments play a substantial role in the preservation of microbial communities, for example, clinical and food-poisoning bacteria. However, the role of wild mushrooms as natural reservoirs of plant pathogenic bacteria remains almost entirely unknown. Furthermore, bacterial transmission from a mushroom species to agricultural plants has rarely been recorded in the literature. In September 2021, a creamy-white Gram-negative bacterial strain was isolated from the sporocarp of (slippery jack) growing in Bermuda grass () lawn in Southern Iran. A similar strain was isolated from the same fungus in the same area in September 2022. Both strains were identified as based on phenotypic features as well as phylogeny of 16S rRNA and three housekeeping genes. The strains were not only pathogenic on white button mushrooms () but also induced hypersensitive reaction (HR) on tobacco and common bean leaves and caused soft rot on a set of diverse plant species, that is, chili pepper, common bean pod, cucumber, eggplant, garlic, gladiolus, narcissus, onion, potato, spring onion, okra, kohlrabi, mango, and watermelon. Isolation of plant pathogenic strains from sporocarp of in two consecutive years in the same area could be indicative of the role of this fungus in the preservation of the bacterium in the natural environment. associated with naturally growing could potentially invade neighboring agricultural crops, for example, vegetables and ornamentals. The potential role of wild mushrooms as natural reservoirs of phytopathogenic bacteria is further discussed.IMPORTANCEThe bacterial genus contains biologically heterogeneous strains that can be isolated from diverse habitats, that is, soil, water, diseased plant material, and clinical specimens. In this study, two Gram-negative pectinolytic bacterial strains were isolated from the sporocarps of in September 2021 and 2022. Molecular phylogenetic analyses revealed that both strains belonged to the complex species , while the pathovar status of the strains remained undetermined. Biological investigations accomplished with pathogenicity and host range assays showed that strains isolated from in two consecutive years were pathogenic on a set of diverse plant species ranging from ornamentals to both monocotyledonous and dicotyledonous vegetables. Thus, could be considered an infectious pathogen capable of being transmitted from wild mushrooms to annual crops. Our results raise a hypothesis that wild mushrooms could be considered as potential reservoirs for phytopathogenic .
Topics: Burkholderia gladioli; Phylogeny; RNA, Ribosomal, 16S; Agaricus; Burkholderia; Vegetables; Basidiomycota
PubMed: 38380912
DOI: 10.1128/spectrum.03395-23 -
Foods (Basel, Switzerland) Jan 2024pv. is a serious safety issue in black fungus due to the deadly toxin, bongkrekic acid. This has triggered the demand for an efficient toxigenic phenotype recognition...
pv. is a serious safety issue in black fungus due to the deadly toxin, bongkrekic acid. This has triggered the demand for an efficient toxigenic phenotype recognition method. The objective of this study is to develop an efficient method for the recognition of toxin-producing strains. The potential of multilocus sequence typing and a back propagation neural network for the recognition of toxigenic was explored for the first time. The virulent strains were isolated from a black fungus cultivation environment in Qinba Mountain area, Shaanxi, China. A comprehensive evaluation of toxigenic capability of 26 isolates were conducted using Ultra Performance Liquid Chromatography for determination of bongkrekic acid and toxoflavin production in different culturing conditions and foods. The isolates produced bongkrekic acid in the range of 0.05-6.24 mg/L in black fungus and a highly toxin-producing strain generated 201.86 mg/L bongkrekic acid and 45.26 mg/L toxoflavin in co-cultivation with on PDA medium. Multilocus sequence typing phylogeny (MLST) analysis showed that housekeeping gene sequences have a certain relationship with a strain toxigenic phenotype. We developed a well-trained, back-propagation neutral network for prediction of toxigenic phenotype in based on MLST sequences with an accuracy of 100% in the training set and an accuracy of 86.7% in external test set strains. The BP neutral network offers a highly efficient approach to predict toxigenic phenotype of strains and contributes to hazard detection and safety surveillance.
PubMed: 38275718
DOI: 10.3390/foods13020351 -
International Journal of Molecular... Dec 2023Celiac disease is an autoimmune disease triggered by oral ingestion of gluten, with certain gluten residues resistant to digestive tract enzymes. Within the duodenum,...
Celiac disease is an autoimmune disease triggered by oral ingestion of gluten, with certain gluten residues resistant to digestive tract enzymes. Within the duodenum, the remaining peptides incite immunogenic responses, including the generation of autoantibodies and inflammation, leading to irreversible damage. Our previous exploration unveiled a glutenase called Bga1903 derived from the Gram-negative bacterium . The cleavage pattern of Bga1903 indicates its moderate ability to mitigate the toxicity of pro-immunogenic peptides. The crystal structure of Bga1903, along with the identification of subsites within its active site, was determined. To improve its substrate specificity toward prevalent motifs like QPQ within gluten peptides, the active site of Bga1903 underwent site-directed mutagenesis according to structural insights and enzymatic kinetics. Among the double-site mutants, E380Q/S387L exhibits an approximately 34-fold increase in its specificity constant toward the QPQ sequence, favoring glutamines at the P1 and P3 positions compared to the wild type. The increased specificity of E380Q/S387L not only enhances its ability to break down pro-immunogenic peptides but also positions this enzyme variant as a promising candidate for oral therapy for celiac disease.
Topics: Humans; Celiac Disease; Catalytic Domain; Glutens; Autoantibodies; Autoimmune Diseases; Gastrointestinal Agents
PubMed: 38203677
DOI: 10.3390/ijms25010505 -
Comparative Medicine Oct 2023Four strains of experimentally naïve mice (NOD. Cg- Il2rg /SzJ [NSG], NOD. Cg- /SzJ [NRG], B6.129S(Cg)-/J [STAT1 ], and B6.129S7- /J[IFNγR ] housed in a barrier...
Four strains of experimentally naïve mice (NOD. Cg- Il2rg /SzJ [NSG], NOD. Cg- /SzJ [NRG], B6.129S(Cg)-/J [STAT1 ], and B6.129S7- /J[IFNγR ] housed in a barrier facility developed unusual and seemingly unrelated clinical signs. Young NSG/NRG mice ( = 49, mean age = 4 ± 0.4 mo) exhibited nonspecific clinical signs of moderate-to-severe lethargy, hunched posture, decreased body condition, and pallor. In contrast to the NSG/NRG mice, the STAT1 and IFNγ R mice ( = 5) developed large subcutaneous abscesses on the head and neck. These mice were euthanized, and samples were collected for culture. NSG/NRG mice had moderate-markedly enlarged livers (20 of 49, 40%) and spleens (17 of 49, 35%). The livers contained multiple, variably-sized, tan regions throughout all lobes. Histology revealed necrotizing hepatitis (13 of 17, 77%), splenic and hepatic extramedullary hematopoiesis (17 of 17, 100%), glomerular histiocytosis (6 of 17, 35%), and metritis (6 of 11, 55%) with perivascular inflammation, suggesting hematogenous spread Differentials for these lesions included mouse hepatitis virus, ectromelia virus, spp., and was cultured from liver lesions and subcutaneous abscesses and confirmed with 16S ribosomal RNA sequencing. After completing systematic testing of the environment, failure of the water autoclave cycle was suspected as the cause of the outbreak. To address the situation, individually ventilated racks were sanitized and new breeders were purchased; these actions dramatically reduced infections. The current literature contains few reports of infections in immunocompromised mice, and its typical presentation is torticollis and rolling. infection is a potential differential for subcutaneous abscesses, hepatitis, and splenomegaly in immunocompromised mice. Careful monitoring of sterilization techniques is essential to prevent such infections in a barrier facility.
Topics: Animals; Mice; Abscess; Burkholderia gladioli; Burkholderia Infections; Hepatitis; Mice, Inbred NOD; Mice, SCID
PubMed: 38087404
DOI: 10.30802/AALAS-CM-23-000016 -
Foods (Basel, Switzerland) Oct 2023Bongkrekic acid (BKA) poisoning, induced by the contamination of pathovar , has a long-standing history of causing severe outbreaks of foodborne illness. In recent... (Review)
Review
Bongkrekic acid (BKA) poisoning, induced by the contamination of pathovar , has a long-standing history of causing severe outbreaks of foodborne illness. In recent years, it has emerged as a lethal food safety concern, presenting significant challenges to public health. This review article highlights the recent incidents of BKA poisoning and current research discoveries on the pathogenicity of pv. and underlying biochemical mechanisms for BKA synthesis. Moreover, the characterization of pv. and the identification of the gene cluster provide a crucial foundation for developing targeted interventions to prevent BKA accumulation in food matrices. The prevalence of the gene cluster, which is the determining factor distinguishing pv. from non-pathogenic strains, has been identified in 15% of documented genomes worldwide. This finding suggests that BKA poisoning has the potential to evolve into a more prevalent threat. Although limited, previous research has proved that pv. is capable of producing BKA in diverse environments, emphasizing the possible food safety hazards associated with BKA poisoning. Also, advancements in detection methods of both BKA and pv. hold great promise for mitigating the impact of this foodborne disease. Future studies focusing on reducing the threat raised by this vicious foe is of paramount importance to public health.
PubMed: 37959045
DOI: 10.3390/foods12213926 -
Molecules (Basel, Switzerland) Oct 2023Glutarimide-containing polyketides exhibiting potent antitumor and antimicrobial activities were encoded via conserved module blocks in various strains that favor the...
Glutarimide-containing polyketides exhibiting potent antitumor and antimicrobial activities were encoded via conserved module blocks in various strains that favor the genomic mining of these family compounds. The bioinformatic analysis of the genome of ATCC 10248 showed a silent -AT PKS biosynthetic gene cluster (BGC) on chromosome 2 (Chr2C8), which was predicted to produce new glutarimide-containing derivatives. Then, the silent polyketide synthase gene cluster was successfully activated via in situ promoter insertion and heterologous expression. As a result, seven glutarimide-containing analogs, including five new ones, gladiofungins D-H (-), and two known gladiofungin A/gladiostatin () and (named gladiofungin C), were isolated from the fermentation of the activated mutant. Their structures were elucidated through the analysis of HR-ESI-MS and NMR spectroscopy. The structural diversities of gladiofungins may be due to the degradation of the butenolide group in gladiofungin A () during the fermentation and extraction process. Bioactivity screening showed that and had moderate anti-inflammatory activities. Thus, genome mining combined with promoter engineering and heterologous expression were proved to be effective strategies for the pathway-specific activation of the silent BGCs for the directional discovery of new natural products.
Topics: Burkholderia gladioli; Polyketides; Piperidones; Genomics; Multigene Family
PubMed: 37836780
DOI: 10.3390/molecules28196937