Search Results (36)

Burkholderia gladioli pv. cocovenenans (B. gladioli pv. cocovenenans), the most representative pathovar of B. gladioli, is capable of producing thermostable and highly virulent bongkrekic acid, which can result in multiple organ failure and an extremely high case fatality rate in humans. This research aims to mine specific targets for B. gladioli pv. cocovenenans and develop a rapid and accurate assay for the detection of B. gladioli pv. cocovenenans in food. Two novel specific target genes (group_0918 and group_0110) were successfully screened through pan-genome analysis, and the excellent specificity and sensitivity of both targets were verified in comparison to PCR assays. Based on these targets, a loop-mediated isothermal amplification (LAMP) method was developed to specifically identify B. gladioli pv. cocovenenans. In pure culture and spiked fresh black fungus samples, the LAMP assay achieved a limit of detection (LOD) of 4.1 × 10¹ CFU/mL and 4.1 × 10² CFU/g for the detection of B. gladioli pv. cocovenenans, respectively. To enable point of care testing, a LAMP-based lateral flow dipstick(LFD) assay was established with a detection sensitivity of 4.1 × 10³ CFU/g in fresh black fungus. Tests on naturally infected food samples demonstrated that the developed LAMP and LAMP-assisted visual detection assays can serve as an effective alternative for the accurate identification of B. gladioli pv. cocovenenans. The novel molecular detection technology established in this study offers an efficient and reliable detection method for the prevention and control of B. gladioli pv. cocovenenans contamination in food, which holds significant application value and promotion prospects. Full article

Rice sheath blight (RSB), caused by Rhizoctonia solani, causes 10–50% yield losses globally. Using 16S rRNA sequencing of 100 rice cultivars, we found that resistant varieties harbor significantly more diverse bacterial communities (3230 OTUs; 2064 unique) than susceptible cultivars (599 OTUs; 36 unique). Resistant varieties were enriched in beneficial Burkholderiaceae, Bacillaceae, and Pseudomonadaceae, while Sphingobacteriaceae and Enterobacteriaceae were predominant in the susceptible rice varieties. From the 260 bacterial isolates, Burkholderia vietnamiensis J14EPLEAF2 presented potent antifungal activity (77% inhibition), suppressed lesion development, and abolished sclerotia formation. This strain displayed multiple plant growth-promoting traits, enhanced seed germination, and primed defense responses by upregulating PR5 and PR10. Hypersensitive response assays confirmed B. vietnamiensis as non-pathogenic, unlike B. gladioli and B. cepacia. This study identifies B. vietnamiensis J14EPLEAF2 as a promising, safe biocontrol agent for sustainable rice disease management. Full article

The genus Burkholderia encompasses both plant pathogenic and beneficial species, yet the genomic determinants underlying this lifestyle divergence remain poorly understood. Using 16S rRNA sequencing of 100 rice cultivars, our companion study demonstrated that resistant varieties are enriched in beneficial Burkholderiaceae, leading to the isolation of three phenotypically contrasting strains. Here, we present comparative genomic analyses of non-pathogenic biocontrol strain Burkholderia vietnamiensis J14EpLeaf2 and pathogenic strains Burkholderia gladioli A1EpSeed5 and Burkholderia cepacia J14Eple. Pathogenic strains possess significantly larger genomes (8.36–8.46 Mb) enriched in mobile genetic elements compared to the streamlined 6.95 Mb genome of B. vietnamiensis. CAZyme analysis revealed broader repertoires of glycoside hydrolases and polysaccharide lyases in pathogens, consistent with enhanced plant cell wall degradation. B. gladioli possesses a complete T3SS and expanded T6SS with 301 predicted effectors, while B. cepacia lacks structural T3SS genes but harbors 271 candidate effectors predicted to be secreted via alternative secretion pathways, compared to 180 in B. vietnamiensis. Notably, B. cepacia harbors cystic fibrosis-associated markers (cable pili, ZmpA/ZmpB), raising significant biosafety concerns that preclude its agricultural application. LC-MS validated IAA, ornibactin, and AHL production in B. vietnamiensis, supporting its plant growth-promoting and biocontrol functions. Computational PPI networks predicted distinct interaction landscapes requiring experimental validation. This study provides a genomic framework for distinguishing pathogenic from beneficial Burkholderia and supports B. vietnamiensis as a safe biocontrol agent while cautioning against B. cepacia J14Eple. Full article

Bongkrekic acid is a lethal mitochondrial toxin produced by Burkholderia gladioli pathovar cocovenenans, posing severe threats to food safety due to their high stability and the lack of effective antidotes. Developing specific, high-affinity recognition elements is crucial to overcoming the limitations of current BA detection methods in food matrices, and thereby safeguarding food safety and public health. In this study, we report for the first time the selection and remodelling of a DNA aptamer with high affinity for BA, which could be used as a promising recognition tool for sensitive BA detection in food. Integrating isothermal titration calorimetry, molecular docking, and molecular dynamics simulations revealed that the binding of BA to F3-1 follows an induced-fit mechanism. This study is the first to report a DNA aptamer with nanomolar affinity for BA, clarify its underlying binding mechanism, and provide a reliable recognition element for sensitive and specific BA detection in food samples. Full article

Brown spot on the leaf sheath is an emerging disease of sweet corn (Zea mays L.) in Sinaloa, Mexico, with an unknown etiology. This study aimed to identify the causal agent of the disease and assess its pathogenicity on commercial sweet corn hybrids. Bacterial strains were isolated from symptomatic leaf sheaths collected from commercial fields. Identification was performed through biochemical profiling (API 50CHB/E), pathogenicity tests on alternative hosts (potato, onion, celery), and molecular analysis (16S rRNA and recA genes sequencing and phylogenetic reconstruction). Pathogenicity and virulence were confirmed by inoculating four sweet corn hybrids in a greenhouse. The strains were Gram-negative rods, identified as Burkholderia gladioli based on biochemical profiles and molecular data (99% 16S rRNA+ recA similarity; phylogenetic clustering within the B. gladioli clade). In greenhouse trials, the strains induced brown spot lesions on the leaf sheaths of all tested hybrids, replicating field symptoms fulfilling Koch’s postulates. This is the first report of B. gladioli as the causal agent of brown spot on the leaf sheath of sweet corn in Mexico. The pathogen’s broad host range highlights its potential as an emerging threat to horticultural crops in the region. Full article

Sugarcane productivity in the Philippines is threatened by ringspot disease caused by Epicoccum sorghinum. This study evaluated the antagonistic potential of sugarcane endophytic bacteria against E. sorghinum using Dual Culture (DCA) and Volatile Compound Assays (VCA). Molecular identification via 16S rRNA sequencing confirmed the bacterial identities. Burkholderia gladioli exhibited the highest inhibition in DCA (57.79%), while Bacillus zhangzhouensis was most effective in VCA (49.56%). Stenotrophomonas rhizophila also demonstrated inhibitory activity (16.55%). These results indicate that these endophytic strains are promising, sustainable biocontrol alternatives to chemical pesticides for managing sugarcane ringspot disease. Future work should focus on validation in screenhouse and field testing. Full article

Burkholderia gladioli is a multifaceted bacterium with both pathogenic and beneficial strains, and nonpathogenic Burkholderia species have shown potential as plant growth-promoting rhizobacteria (PGPRs) and biocontrol agents. However, the molecular mechanisms underlying their beneficial functions remain poorly characterized. This study systematically investigated the antimicrobial mechanisms and plant growth-promoting properties of B. gladioli strain ZBSF BH07, isolated from the grape rhizosphere, by combining genomic and functional analyses, including whole-genome sequencing, gene annotation, phylogenetic and comparative genomics, in vitro antifungal assays, and plant growth promotion evaluations. The results showed that ZBSF BH07 exhibited broad-spectrum antifungal activity, inhibiting 14 grape pathogens with an average inhibition rate of 56.58% and showing dual preventive/curative effects against grape white rot, while also significantly promoting grape seedling growth with increases of 54.9% in plant height, 172.9% in root fresh weight, and 231.34% in root dry weight. Genomic analysis revealed an 8.56-Mb genome (two chromosomes and one plasmid) encoding 7431 genes and 26 secondary metabolite biosynthesis clusters (predominantly nonribosomal peptide synthetases), supporting its capacity for antifungal metabolite secretion, and functional analysis confirmed genes for indole-3-acetic acid (IAA) synthesis, phosphate solubilization, and siderophore production. These results demonstrate that ZBSF BH07 suppresses pathogens via antifungal metabolites and enhances grape growth through phytohormone regulation and nutrient acquisition, providing novel insights into the dual mechanisms of B. gladioli as a biocontrol and growth-promoting agent and laying a scientific foundation for developing sustainable grapevine disease management strategies. Full article

Auricularia (wood ear fungus) is susceptible to Burkholderia gladioli pv. cocovenenans (BGC) and causes food poisoning. This study investigated pulsed-light (PL) inactivation of BGC on Auricularia. The evaluation of PL parameters indicated that lower initial biomass, shorter distance, and more fluences were more effective in inactivating BGC. This study achieved 5~8 Log reductions in BGC in phosphate-buffered saline and ~4 Log reductions in Auricularia auricula and Auricularia cornea var. Li, and the survivor curves fit the Weibull model well with R² values of 0.943~0.987 and RMSE values of 0.308~0.430 in all three substrates. PL caused cell membrane damage, leading to DNA, protein, and ATP leakage and increased ROS production. PL caused an alteration in color (ΔE 3.01~7.67) but not springiness and cohesiveness in the texture of Auricularia at 11.80~35.40 J/cm². In all, PL is effective in inactivating BGC on the surface of Auricularia at 35.40 J/cm² and can be taken as a good controlling measure. Full article

The toxicity associated with bongkrekic acid (BKA) is severe due to its chemical structure, which also facilitates high mortality rates; however, its isomer, isobongkrekic acid (iBKA), with only minor structural variance, demonstrates marked differences in toxicity. This discrepancy in structural properties and toxicity highlights that risks have been potentially underestimated within current detection standards for BKAs. In this study, a novel BKA trans isomer at the C8 and C9 double carbon bonds (E-configuration), termed iBKA-neo, was successfully separated and identified. Subsequently, the multiple reaction monitoring parameters and chromatographic conditions for three BKA isomers were optimized, enabling effective separation within 15 min via UHPLC-MS/MS, among which the ammonium positive adduct ions yielded significantly higher response intensities for all BKA isomers than traditional deprotonated molecules. Additionally, distinct differences in the ion ratios between iBKA-neo and BKA were utilized for preliminary screening. On this basis, the extraction and enrichment strategies for BKAs were optimized in food matrices and validated comprehensively with good linearity (0.25–500 μg/kg), a superior limit of quantification (0.25 μg/kg), acceptable recoveries (82.32–114.84%), and stable intraday and interday precision (an RSD less than 12.67%). These findings significantly contribute to ecotoxicology and the formulation of safety standards concerning BKAs. Full article

Burkholderia gladioli pathovar cocovenenans (BGC) is a highly lethal foodborne pathogen responsible for outbreaks of food poisoning with the highest recorded mortality rates among bacterial foodborne illnesses in China. In this study, the ecological behavior of BGC and its Bongkrekic Acid (BA) production dynamics in fresh wet rice noodles (FWRN) were investigated under isothermal conditions ranging from 4 °C to 37 °C. Growth kinetics were modeled using the Huang, Baranyi, and modified Gompertz primary models, with secondary models (Huang square root model and Ratkowsky square root model) describing the influence of temperature on growth parameters. Among these, the Huang–Huang model combination exhibited the best performance, with a root mean square error (RMSE) of 0.009 and bias factor (B_f) and accuracy factor (A_f) values close to 1. Additionally, we examined the impact of BGC contamination on the quality attributes of FWRN, including pH, color (L*, a*, b*), hardness, and moisture content. The results indicated that BGC growth significantly increased pH and yellowing (b*) values, while changes in texture and moisture were less pronounced. A probabilistic model was further developed to predict BA production under various temperature scenarios, revealing that BA formation was most likely to occur between 24 °C and 30 °C. While this study provides valuable predictive tools for microbial risk assessment and quality control of FWRN, limitations include the exclusion of additional environmental factors such as oxygen and relative humidity, as well as the lack of direct investigation into the degradation behavior of BA. Future research will expand model parameters and include sensory evaluations and advanced microbiological analyses to enhance applicability under real-world storage and transportation conditions. Full article

For plant diseases to become established, plant pathogens require not only virulence factors and susceptible hosts, but also optimal environmental conditions. The accumulation of high soil salinity can have serious impacts on agro-biological ecosystems. However, the interactions between plant pathogens and salinity have not been fully characterized. This study investigated the effects of salt stress on representative plant pathogens, such as Burkholderia gladioli, Burkholderia glumae, Pectobacterium carotovorum subsp. carotovorum (Pcc), Ralstonia solanacearum, and Xanthomonas oryzae pv. oryzae. Phenotypic assays revealed that B. gladioli and R. solanacearum are highly sensitive to salt stress, exhibiting significant reductions in growth, motility, and enzyme production, whereas Pcc showed notable tolerance. Pan-genome-based comparative transcriptomics identified co-downregulated patterns in B. gladioli and R. solanacearum under stress conditions, indicating the suppression of bacterial chemotaxis and type III secretion systems. Uniquely upregulated patterns in Pcc were associated with enhanced survival under high salinity, such as protein quality control, osmotic equilibrium, and iron acquisition. Additionally, the application of salt stress combined with the beneficial bacterium Chryseobacterium salivictor significantly reduced tomato wilt caused by R. solanacearum, suggesting a potential management strategy. This study underscores practical implications for effectively understanding and controlling plant pathogens under future climate changes involving salt stress. Full article

Jiuqu (starter) makes an important contribution to the formation of the flavor characteristics of Hongqu rice wine (HQW). Gutian Qu (GTQ) and Wuyi Qu (WYQ) are two kinds of Jiuqu commonly used in HQW brewing, but the comparison of the two kinds of HQW is still insufficient at present. The objective of this study was to compare the dynamic changes of amino acids (AAs), higher alcohols (HAs), bioamines (BAs), volatile flavor compounds (VFCs), and microbial communities in HQW fermentation, with GTQ and WYQ as starter. This study used an automatic amino acid analyzer, GC, HPLC, and GC-MS to detect AAs, HAs, Bas, and VFCs during fermentation; metagenomic sequencing technology was used to elucidate the microbial community and its functional characteristics. The results showed that the contents of AAs and HAs in HQW brewed with WYQ (WYW) were significantly higher than those in HQW brewed with GTQ (GTW). On the contrary, the majority of BAs in GTW were significantly higher than those in WYW. The composition of VFCs in WYW and GTW were obviously different, as most of the VFCs were notably enriched in WYW, while ethyl caproate, isoamyl acetate, ethyl heptanoate, ethyl nonanoate, 1-decanol, citronellol, phenethyl acetate, and hexanoic acid were more abundant in GTW. Burkholderia gladioli, Pantoea dispersa, Weissella cibaria, Monascus purpureus, and Saccharomyces cerevisiae were the predominant microbial populations in GTW brewing at the species level, while Sphingomonas sp., Kosakonia cowanii, Enterobacter asburiae, Leuconostoc lactis, Aspergillus niger, and Saccharomyces cerevisiae were the dominant microbial species in WYW brewing. The abundance of functional genes involved in BAs biosynthesis were much higher in GTW brewing, while the abundance of functional genes related to the metabolism of characteristic VFCs were much higher in WYW brewing. Collectively, these findings provided evidence for elucidating the effects of Jiuqu and microbial communities on HQW flavor quality, and laid a solid foundation for the improvement of HQW flavor quality. Full article

Burkholderia gladioli pv. cocovenenans 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 B. gladioli strains. The potential of multilocus sequence typing and a back propagation neural network for the recognition of toxigenic B. cocovenenans 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 Rhizopus oryzae 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 B. gladioli 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. Full article

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 Burkholderia gladioli. 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. Full article

Bongkrekic acid (BKA) poisoning, induced by the contamination of Burkholderia gladioli pathovar cocovenenans, 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 B. gladioli pv. cocovenenans and underlying biochemical mechanisms for BKA synthesis. Moreover, the characterization of B. gladioli pv. cocovenenans and the identification of the bon gene cluster provide a crucial foundation for developing targeted interventions to prevent BKA accumulation in food matrices. The prevalence of the bon gene cluster, which is the determining factor distinguishing B. gladioli pv. cocovenenans from non-pathogenic B. gladioli strains, has been identified in 15% of documented B. gladioli 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 B. gladioli pv. cocovenenans 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 B. gladioli pv. cocovenenans 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. Full article