Collection Of Strains Research Articles

Antimicrobial activity of Lactobacillus casei on Staphylococcus pseudintermedius isolates.

Antimicrobial resistance is increasing each year. For example, in 2019 it was directly responsible for an estimated >1 million deaths. Additionally, the development of new drugs is much slower, generating enormous concerns about responses to infection in the future health scenario. Therefore, probiotics have emerged as an alternative to antibiotics. This study aimed to isolate and identify a Lactobacillus casei from healthy canine skin and investigate its antimicrobial effect on isolates of Staphylococcus pseudintermedius originating from dogs with pyoderma. L. casei was isolated from skin samples collected with a sterile cotton swab from the inner pinnae of healthy dogs. It was then cultured, identified using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry, and tested against 30 different clinical isolates and one American Type Culture Collection strain of S. pseudintermedius using the spot-on-the-lawn technique. Its safety was assessed through a modified Kirby-Bauer disc diffusion susceptibility test. L. casei inhibited the growth of all isolates of S. pseudintermedius. The mean value of the inhibition halo of all isolates was 11.3 mm. A significant positive correlation (Pearson's linear correlation = 0.444; p = 0.014) was noted between the inhibitory halos formed by L. casei on the S. pseudintermedius isolates and the halos produced by the tested antimicrobial discs on the same isolates. The L. casei strain demonstrated sensitivity to all tested antimicrobials. The study indicates that using commensal bacteria from canine skin, specifically L. casei, to control bacterial infections caused by S. pseudintermedius can be a promising complementary or alternative therapy to antibiotics relevant to animal and human health.

The Challenge of Developing a Test to Differentiate Actinobacillus pleuropneumoniae Serotypes 9 and 11

Actinobacillus pleuropneumoniae is a major swine pathogen, classified into 19 serotypes based on capsular polysaccharide (CPS) loci. This study aimed to improve the diagnostic method to differentiate between serotypes 9 and 11, which are challenging to distinguish using conventional serological and molecular methods. A novel qPCR assay based on locked nucleic acid (LNA) probes was developed and validated using a collection of reference strains representing all known 19 serotypes. The assay demonstrated specificity in detecting the nucleotide variation characteristic of the serotype 9 reference strain. However, the analysis of a clinical isolate collection identified discrepancies between LNA-qPCR and serological results, prompting further investigation of the cps and O-Ag loci. Subsequent nanopore sequencing and whole-genome sequencing of a collection of 31 European clinical isolates, previously identified as serotype 9, 11, or undifferentiated 9/11, revealed significant genetic variations in the cps and O-Ag loci. Ten isolates had a cpsF sequence identical to that of the serotype 11 reference strain, while six isolates had single-nucleotide polymorphisms that were unlikely to cause significant coding changes. In contrast, 15 isolates had interruptions in the cpsF gene, distinct from that found in the serotype 9 reference strain, potentially leading to a serotype 9 CPS structure. In the O-Ag loci, differences between serotypes 9 and 11 were minimal, although some isolates had mutations potentially affecting O-Ag expression. Overall, these findings suggest that multiple genetic events can lead to the formation of a serotype 9 CPS structure, hindering the development of a single qPCR assay capable of detecting all cpsF gene mutations. Our results suggest that, currently, a comprehensive analysis of the cpsF gene is necessary to accurately determine whether the capsule of an isolate corresponds to serotype 9 or 11. Although such analyses are feasible with the advent of third-generation sequencing technologies, their accessibility, cost, and time to result limit their use in routine diagnostic applications. Under these circumstances, the designation of the hybrid serovar 9/11 remains a valid approach.

P1325 Metabolic dynamics of the small intestinal microbiota upon nutritional interventions

Abstract Background The human small intestinal microbiota, which plays a crucial role in intestinal function, remains poorly investigated due to limited accessibility. Methods We utilise the access via Ileostomies in a randomised cross-over trial with two nutritional interventions (high carb vs. high fat). Stoma effluent samples are collected from 70 stoma patients hourly (0-6h) after the intervention, along with blood and urine samples (0h, 3h, 6h). Stoma effluent samples from each study day are anaerobically cultured to generate a collection of small intestinal bacteria strains. Results We characterise the small intestinal microbiota through taxonomy (16S sequencing), biomass, and metabolome analysis. Shotgun metagenomic and mRNA sequencing are performed at selected timepoints. Our comprehensive “multi-omics" analysis involves identifying bacterial networks, interpreting their dynamics. In parallel, we have created a bacterial isolate catalogue (>1000 isolates, ~200 species) form human samples to reproduce key interactions in vitro. Conclusion This study aims for a comprehensive analysis of small intestinal microbiota dynamics in the context of different nutritional interventions. The data and samples collected will enable hypothesis testing in vitro and lay the groundwork for future disease-specific investigations. Additionally, by establishing an extensive catalogue of well-characterised human-derived bacterial isolates, we created a resource for future experimental research projects.

Forecasting High Cycle and Very High Cycle Fatigue Through Enhanced Strain-Energy Based Fatigue Life Prediction

Abstract This study applies a novel strain-energy based fatigue life prediction method to low cycle fatigue (LCF) data additive manufactured (AM) Inconel 718 round dog-bones, specifically focusing on cycles to failure less than 105. The objective is to forecast high cycle fatigue (HCF, 106–107) and very high cycle fatigue (VHCF >107), aiming to approximate stress versus cycles to failure (SN) behavior and the inherent variability in the fatigue life of the material system. This tool is motivated by the need to characterize an expanding and diverse array of materials produced by additive manufacturing methods, process parameter modifications, and optimizations, which can significantly impact fatigue life and overall structural reliability. The fatigue life prediction method achieves this by generating a fatigue life distribution as a function of stress amplitude. Bayesian statistical inference and stochastic sampling techniques are employed iteratively for each test data point, incorporating stress, cycles to failure, and total strain-energy dissipated leading to fatigue failure. Experimental LCF fatigue data are acquired using a standard axial servohydraulic load frame equipped with an axial extensometer for strain and strain-energy data collection. HCF and VHCF data is generated utilizing an ultrasonic fatigue test frame capable of cycling at 20 kHz. The fatigue data obtained from both servohydraulic and ultrasonic fatigue testing are presented and compared. The energy-based fatigue life prediction framework, utilizing only LCF data, is deployed to forecast HCF and VHCF fatigue behavior for AM Inconel 718 fatigue. The HCF and VHCF data generated are then used to validate the forecasts generated from the novel energy-based fatigue life prediction method. Comparisons are made against Random Fatigue Limit curve estimations to assess the effectiveness and accuracy of the proposed methodology.

Exploring 1-alkene biosynthesis in bacterial antagonists and Jeotgalicoccus sp. ATCC 8456.

Terminal olefins are important platform chemicals, drop-in compatible hydrocarbons and also play an important role as biocontrol agents of plant pathogens. Currently, 1-alkenes are derived from petroleum, although microbial biosynthetic routes are known. Jeotgalicoccus sp. ATCC 8456 produces 1-alkenes via the fatty acid decarboxylase OleTJE. UndA and UndB are recently identified non-heme iron oxidases converting medium-chain fatty acids into terminal alkenes. Our knowledge about the diversity and natural function of OleTJE, UndA, and UndB homologs is scarce. We applied a combined screening strategy-solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME GC-MS) and polymerase chain reaction (PCR)-based amplification-to survey an environmental strain collection for microbial 1-alkene producers and their corresponding enzymes. Our results reinforce the high level of conservation of UndA and UndB genes across the genus Pseudomonas. In vivo production of defined 1-alkenes (C9-C13; C15; C19) was directed by targeted feeding of fatty acids. Lauric acid feeding enabled 1-undecene production to a concentration of 3.05mg l-1 in Jeotgalicoccus sp. ATCC 8456 and enhanced its production by 105% in Pseudomonas putida 1T1 (1.10mg l-1). Besides, whole genome sequencing of Jeotgalicoccus sp. ATCC 8456 enabled reconstruction of the 1-alkene biosynthetic pathway. These results advance our understanding of microbial 1-alkene synthesis and the underlying genetic basis.

Long-term homeostasis in microbial consortia via auxotrophic cross-feeding.

Synthetic microbial consortia are collections of multiple strains or species of engineered organisms living in a shared ecosystem. Because they can separate metabolic tasks among different strains, synthetic microbial consortia have myriad applications in developing biomaterials, biomanufacturing, and biotherapeutics. However, synthetic consortia often require burdensome control mechanisms to ensure that the members of the community remain at the correct proportions. This is especially true in continuous culture systems in which slight differences in growth rates can lead to extinctions. Here, we present a simple method for controlling consortia proportions using cross-feeding in continuous auxotrophic co-culture. We use mutually auxotrophic E. coli with different essential gene deletions and regulate the growth rates of members of the consortium via cross-feeding of the missing nutrients in each strain. We demonstrate precise regulation of the co-culture steady-state ratio by exogenous addition of the missing nutrients. We also model the co-culture's behavior using a system of ordinary differential equations that enable us to predict its response to changes in nutrient concentrations. Our work provides a powerful tool for consortia proportion control with minimal metabolic costs to the constituent strains.

A protein interaction map of the myosin Myo2 reveals a role of Alo1 in mitochondrial inheritance in yeast.

Budding yeast cells multiply by asymmetric cell division. During this process, the cell organelles are transported by myosin motors along the actin cytoskeleton into the growing bud, while at the same time some organelles must be retained in the mother cell. The ordered partitioning of organelles depends on highly regulated binding of motor proteins to cargo membranes. To search for novel components involved in this process, we performed a protein fragment complementation screen using the cargo binding domain of Myo2, the major organelle transporter in yeast, as a bait and a genome-wide strain collection expressing yeast proteins as prey. One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. We found that mutants lacking Alo1 exhibit defects in mitochondrial morphology and inheritance. During oxidative stress dysfunctional mitochondria are immobilized in the mother in wild type cells. Intriguingly, overexpression of ALO1 restores bud-directed transport of mitochondria under these conditions. We propose that Alo1 supports the recruitment of Myo2 to mitochondria and its activity is particularly important under oxidative stress.

Four novel nontuberculous mycobacteria species: Mycobacterium wendilense sp. nov., Mycobacterium burgundiense sp. nov., Mycobacterium kokjensenii sp. nov. and Mycobacterium holstebronense sp. nov. revived from a historical Danish strain collection.

Four novel nontuberculous mycobacteria were discovered from a historical strain collection at the International Reference Laboratory of Mycobacteriology at Statens Serum Institut in Copenhagen, Denmark. Phylogenetic analysis combining the 16S rrs, internal transcribed spacer and 23S rrl elements, as well as a single-copy core-gene (hsp65, rpoB+C, secA and tuf) analysis of these freeze-dried mycobacteria, clinically isolated from gastric lavage samples between 1948 and 1955, showed to be associated with type strains grouping within the Terra and Fortuitum-Vaccae clade. Phenotypic characteristics, biochemical properties and fatty acid and mycolic acid profiles supported the classification as novel strains. A genomic comparison to the closest related type strain was done by calculating average nucleotide identity and in silico DNA:DNA hybridization values, which showed 87.9% and 33.0% for Mu0050, 85.2% and 27.4% for Mu0053, 85.3% and 27.6% for Mu0083 and 93.3% and 50.1% for Mu0102, respectively. The names proposed for the new species are Mycobacterium wendilense sp. nov. (Mu0050T=ITM 501390T=CCUG 77525T), Mycobacterium burgundiense sp. nov. (Mu0053T=ITM 501391T=CCUG 77526T), Mycobacterium kokjensenii sp. nov. (Mu0083T=ITM 501392T=CCUG 77527T) and Mycobacterium holstebronense sp. nov. (Mu0102T=ITM 501393T=CCUG 77528T).

New insights into the epidemiology of Streptococcus suis in pig production systems using whole genome sequencing.

Streptococcus suis (S. suis) is a major pathogen for pigs, causing large economic losses to the swine industry. Moreover, this bacterium has a zoonotic potential, being capable of infecting humans in close contact with pigs or, less frequently, through contact with pork products. Given its importance in both veterinary and public health, S. suis remains a key topic of research. This study explores the genetic characteristics of 154 S. suis isolates obtained from clinical samples collected from pigs between 2018 and 2022. Whole genome sequencing (WGS) allowed a comprehensive analysis of the S. suis population in Spain, including detection of serotype, sequence type (ST), antimicrobial resistance genes, and virulence-associated genes. This approach also explored the vertical transmission of this pathogen through vertically integrated pyramids, as evidenced by associations between grandmother and mother sow farms, and phylogenetic groups, serotypes, and STs. Our analysis revealed that serotype 9 was the most prevalent in our strain collection, predominantly associated with ST123. Notably, the three most significant virulence genes, encoding the extracellular protein factor (EPF), the muramidase-release protein (MRP), and suilysin (SLY), were not consistently present in all clinical isolates. Regarding antimicrobial resistance, no phenotypic resistance was observed to ceftiofur or florfenicol, while observing low resistance to ampicillin (0.6 %) and enrofloxacin (2.6 %), intermediate resistance to penicillin (22.1 %), and high percentage of non-wild-type isolates to trimethoprim-sulfamethoxazole (57.1 %), and doxycycline (96.1 %). The most prevalent antimicrobial resistance genes (ARGs) were tet(O) (85.1 %) and erm(B) (86.4 %), conferring resistance to tetracyclines and macrolides, respectively, although macrolides were not included in the phenotypic testing. Overall, this study provides key epidemiological insights into this significant systemic pathogen within the Spanish swine population. The findings underscore the importance of understanding sample origins, such as grandmother and mother sow farms, to develop an effective antimicrobial stewardship program for managing S. suis-associated diseases.

Study of Exopolysaccharide Production by Lactic Acid Bacteria used in the Baking Industry and Comparison of Methods for Their Determination

Introduction: Exopolysaccharides are high molecular weight compounds consisting of monosaccharide residues and their derivatives, which have biological activity and play a protective role in physiological processes. The search for strains of lactic acid bacteria producing exopolysaccharides is a promising area of research due to their proven positive effect on the rheological properties of fermented food products, as well as human health.Purpose: To study the ability of lactic acid bacteria strains from the collection of FGANU NIIHP to produce exopolysaccharides, as well as to compare different methods of their determination - gravimetric, phenol-sulfuric acid Dubois method, anthrone reagent method and titrimetric Bertrand method.Materials and Methods: To determine the ability to produce exopolysaccharides, cultures of lactic acid bacteria were cultured on 12% malt mash for 48 hours at the optimum temperature for each strain. After protein removal and dialysis, the amount of exopolysaccharides was determined in the culture fluid by different methods.Results: It was found that all the collection strains formed exopolysaccharides in different amounts. The strains producing the highest amount of exopolysaccharides were identified as L.amilolyticus-2, L. plantarumA-63(d), L.amilolyticus-1, L.brevis-78(d), L. paracasei-6. The yield of the product containing exopolysaccharides produced by lactic acid bacteria ranged from 7 to 14.4 mg in 1 ml of culture liquid. The results of the study allowed us to conclude the correctness of Dubois method for estimating the content with respect to exopolysaccharides produced by lactic acid bacteria.Conclusion: The conducted studies confirm the ability of strains of lactic acid bacteria, from the collection of FGANU NIIHP, to produce exopolysaccharides. The correctness of the Dubois method for the determination of exopolysaccharides produced by lactic acid bacteria was established.

Description of four new species of Mychonastes (Chlorophyceae) from Japanese freshwater habitats based on molecular and morphological data

SUMMARYSpecies of the green algal genus Mychonastes have been recognized as ubiquitous ultrasmall components of freshwater communities worldwide, mainly based on molecular data. However, detailed taxonomic identification of Japanese members of Mychonastes has not yet been conducted. We taxonomically identified species of 13 Mychonastes strains in the Microbial Culture Collection at the National Institute for Environmental Studies originating from Japan based on molecular data and comparative morphology. The strains were classified into 10 species, including four new species, Mychonastes ariiae Nozaki sp. nov. (NIES‐2900), Mychonastes takamurae Nozaki sp. nov. (NIES‐2334, 2336), Mychonastes kasaiae Nozaki sp. nov. (NIES‐3743) and Mychonastes gigas Nozaki sp. nov. (NIES‐2340). Ultrastructural features of the cell walls and chloroplasts of these four species were consistent with the generic concept of Mychonastes. The four new species are distinguishable from other species of Mychonastes based on differences in nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS) sequences and morphological features including the mucilaginous matrix surrounding the cells, mode of rupture of the mother cell wall during daughter cell release, formation of large colonies in liquid culture and colony morphology on agar plates. The evolution of Mychonastes species is discussed based on phylogenetic inferences obtained using a combined dataset for four chloroplast genes (psaB, rbcL, psbC and atpB) and rDNA ITS sequences.

Performance of the VITEK® MS system for the identification of filamentous fungi in a microbiological laboratory in Chile

Filamentous fungi are an emergent cause of severe infections in immunocompromised patients. Timely and accurate identification is crucial to initiate appropriate therapy. Traditional identification methods are time-consuming, labor-intensive, and operator-dependent. Matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry is a rapid and easy-to-perform identification method. The effectiveness of a commercial MALDI-TOF MS platform to identify filamentous fungi in a clinical laboratory was evaluated. The study included 67 fungal isolates from 35 species/species complexes, which were identified and confirmed in mycology reference laboratories; 32 derived from clinical samples, 34 from strain collections and one was an ATCC strain. The study used the VITEK® MS system (v3.2.0 database), after sample extraction by VITEK® MS Mould Kit. Results were classified as “correct species”, “correct species complex”, “correct genus”and “no identification”. VITEK® MS correctly identified 91.0% of isolates (58.2% to species, 29.9% to species complex, and 1.5% to genus level only). In 82%, the result matched the species/species complex identified by reference methods. No misidentifications were observed. The kit was rapid and easy to use. In conclusion, the VITEK® MS system showed a high capability to accurately identify filamentous fungi in a clinical laboratory.

ANTAGONISTIC ACTIVITY OF BLACK SEA ACTINOBACTERIA AGAINST PHYTOPATHOGENIC MICROORGANISMS

The biological method of plant protection is an environmentally safe and priority form in long-term programs to combat pathogens and one of the important tools for the transition to organic and ecological agriculture in Ukraine. Aim. To define the antagonistic activity of the Black Sea actinobacteria against phytopathogenic microorganisms. Methods. The antagonistic activity of 35 strains of actinobacteria isolated from different biotopes of the Odesa Bay of the Black Sea against collection and isolated from affected cereal plants phytopathogenic microorganisms was determined by the block method after preliminary cultivation of actinobacteria on Gause 2 medium for 12 days at 28±1 °C. The antagonistic activity of extracted secondary metabolites of Streptomyces ambofaciens ONU 1016 and S. ambofaciens ONU 561 against Fusarium oxysporum strains was determined by the disk-diffusion method. Results. Of the 35 studied, the growth of at least one strain of phytopathogenic bacteria and fungi was inhibited by 77.1% and 65.7% of actinobacterial strains, respectively. The sizes of the zones of no growth of sensitive collection strains of bacteria ranged from 15.3±0.1 mm to 29.6±0.3 mm, and of bacterial strains isolated from affected plants – from 14.5±0.1 mm to 25.7±0.3 mm under the action of antagonistically active actinobacteria. This indicator for collection strains of fungi was determined in the range from 16.0±0.2 mm to 33.5±0.3 mm, for isolated strains of fungi – from 15.0±0.1 mm to 29.3±0.3 mm. S. ambofaciens ONU 1016 and S. ambofaciens ONU 561 showed the best activity against all strains of phytopathogenic microorganisms, in particular against F. oxysporum isolated from affected plants, the zones of no growth of more than 80.0% of the strains of which exceeded 20.0 mm. The extracted secondary metabolites of both S. ambofaciens strains inhibited the growth of the collection and isolated fusarium strains. The zones of no growth of fungi varied widely and depended, primarily, on the strains of fusarium, streptomyces, the concentration of extracts, and the period of recording the results. The minimum inhibitory concentrations of extracted metabolites of S. ambofaciens ONU 1016 and S. ambofaciens ONU 561 against the isolated strains of F. oxysporum were 250 μg/ml – 500 μg/ml and 250 μg/ml – 100 μg/ml, respectively. Conclusions. Actinobacterial strains isolated from sponges and mussels of the Odesa Bay of the Black Sea are antagonistically active against phytopathogenic microorganisms, in particular the fungi F. oxysporum. Collection strains of phytopathogens are more sensitive to the action of sea actinobacteria than strains isolated from affected plants. Strains S. ambofaciens ONU 1016 and S. ambofaciens ONU 561, which showed high antagonistic activity, can be recommended for the creation of a microbial preparation for protecting plants from bacterial and fungal pathogens.

A proteome-wide yeast degron collection for the dynamic study of protein function.

Genome-wide collections of yeast strains, known as libraries, revolutionized the way systematic studies are carried out. Specifically, libraries that involve a cellular perturbation, such as the deletion collection, have facilitated key biological discoveries. However, short-term rewiring and long-term accumulation of suppressor mutations often obscure the functional consequences of such perturbations. We present the AID library which supplies "on demand" protein depletion to overcome these limitations. Here, each protein is tagged with a green fluorescent protein (GFP) and an auxin-inducible degron (AID), enabling rapid protein depletion that can be quantified systematically using the GFP element. We characterized the degradation response of all strains and demonstrated its utility by revisiting seminal yeast screens for genes involved in cell cycle progression as well as mitochondrial distribution and morphology. In addition to recapitulating known phenotypes, we also uncovered proteins with previously unrecognized roles in these central processes. Hence, our tool expands our knowledge of cellular biology and physiology by enabling access to phenotypes that are central to cellular physiology and therefore rapidly equilibrated.

Antibacterial Potential of Selected Traditional Medicinal Plants for Wound Healing in Sekela District, Northwestern Ethiopia

ABSTRACT This study evaluated the antibacterial activity of medicinal plants (MPs) used to treat wounds. Methanol and ethyl acetate crude extracts of four medicinal plants were examined for antibacterial efficacy against gram-positive and gram-negative American Type Culture Collection (ATCC) strains. Plant crude extracts were produced using the maceration technique and analyzed using qualitative phytochemical tests. The antibacterial properties of plant products were evaluated using the agar disc diffusion assay. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations. The data were analyzed using Analysis of Variance (ANOVA). The methanol extract of Rumex nervosus had the highest yield (21%). The methanol extracts of all tested MPs tested positive for alkaloids, phenolics, and tannins. The methanol and ethyl acetate extracts exhibited a dose-dependent increase in the growth inhibition zone against all ATCC. The methanol extract of Plantago lanceolata demonstrated the highest antibacterial activity (16.67 ± 1.15) against Staphylococcus epidermidis. S. aureus and S. epidermidis recorded a relatively lower MIC (6.25 mg mL−1) from methanol extracts of P. lanceolata, while P. lanceolata and R. nervosus recorded a lower MBC (25 mg mL−1) against S. aureus.

The Antibacterial Activity of Yeasts from Unique Biocenoses.

The replenishment of our stock of substances that possess a therapeutic potential is an important objective in modern biomedicine. Despite the important advances achieved in chemical synthesis, the natural diversity of organisms and microorganisms remains an important source of biologically active compounds. Here, we report the results of our study of a unique collection containing more than 3,000 samples of yeasts found on the Kamchatka Peninsula, the Kuril Islands, and Sakhalin Island, Russia. Since yeast and bacteria coexist in a variety of habitats and can interact with each other, we analyzed the antibacterial activity of the collection of yeast strains towards E. coli cells using a fluorescent bacterial reporter. It was uncovered that the Sakhalin strains for the most part stimulate bacterial growth, while most of the strains found on the Kamchatka Peninsula possess inhibitory properties. Moreover, the samples with the most pronounced antibacterial activity, identified as members of the genus Cryptococcus (Naganishia), were found in a gorge in the vicinity of Pauzhetka village on the Kamchatka Peninsula on wormwood (Artemisia vulgaris) and thistle (Onopordum acanthium). Our data indicate that the combination of a plant and its growth site is important for the emergence of yeast strains capable of secreting antibacterial compounds.

The influence of Pseudomonas syringae pv. aptata on the functional characteristics of the microgametophyte of beetroot varieties with different levels of resistance to bacteriosis

Relevance. An increase in the spread of bacteriosis on beetroot in the conditions of the Moscow region carries an epidemiological danger, which actualizes research on the development of a method-ology for evaluating table beet plants for resistance to bacteriosis in the early stages of ontogenesis. The aim of the research. To identify the nature of the relationship between the reaction of sporophyte and microgametophyte to infection with Pseudomonas syringae pv. aptata (Psa) bacterium of beet-root varieties with different resistance of root crops to bacteriosis.Materials and methods. Objects of research: beetroot plants of the Marusya and Krasny Barhat varietal populations, collection strain Psa 1-21. Using phytopathological methods and methods of gamete breeding, plant resistance was assessed in various variants of infection of sporophyte and gametophyte with suspension and culture filtrate of Psa.Results. The average volume of the affected area of the Psa root crops of the Marusya variety was 3.5 times greater than that of the Krasny Barhat variety (Vp = 53 mm3), which is characterized by alignment and absence of susceptible forms (Vp >300 mm3). The Marusya variety has a wide intrapopulation polymorphism in the stability of root crops and leaves, where most genotypes showed medium or high susceptibility to the pathogen. Both varieties showed an increase of 10-30% relative to the control of pollen viability at high (CFU 12*108 cl/ml) and low (CFU 2.4*108 cl/ml) concentrations of the pathogen. The positive effect of Psaon the growth of pollen tubes was noted: in the Marusya variety, as the concentration increased, the stimulating effect increased, in the Krasny Barhat variety, it gradually decreased. When adding a 2.5-fold diluted Psa culture filtrate, the susceptible Marusya variety showed an increase in pollen viability (by 3%), and the resistant Krasny Barhat variety showed a 24% decrease relative to the control. According to the growth rate of the pollen tube, the 4:6 dilution was also differentiating, where the average length of the tubes of the susceptible variety exceeded the control by 10%, and in the stable variety it was 18% lower than the control variant.Conclusion. An inverse relationship was revealed between the resistance of sporophyte to Psa and changes in the functional parameters of the microgametophyte of beetroot varieties Marusya and Krasny Barhat under the influence of a phytopathogen. The results obtained indicate the prospects for the development of a methodology for the selection of bacteriosis-resistant genotypes of beetroot by the reaction of microgametophyte.

Reversible stochastic epigenetic like silencing of the production of pulcherriminic acid in the antimicrobial antagonist Metschnikowia Pulcherrima

The ability to produce pulcherriminic acid is a characteristic feature of yeast species of the pulcherrima clade recently merged under the taxonomic name Metschnikowia pulcherrima. This iron chelator cyclodipeptide forms pulcherrimin, a maroon-red pigment with ferric ions. Its synthesis and secretion into the environment is under the control of closely linked genes referred to as the PUL cluster. The examination of 18 generations of single-cell clones generated from a stock culture of the collection strain 11-1090 (CBS 10359) in this study revealed that the biosynthesis of pulcherriminic acid is reversibly switched on and off during the propagation of cells in a way similar to the epigenetic silencing and activation of gene expression (bimodal active/silent state) in near-heterochromatic regions of other yeast species. As the strain is heterozygous for PUL2 alleles encoding slightly different amino acid sequences and has a plastic genome structure, the efficiency of pulcherriminic acid synthesis in the switched-on state is presumed to depend on which PUL2 allele is active and on structural changes in the genome. The transitions between the active and silent states of pulcherriminic acid synthesis are associated with transitions between the active and silent states of antimicrobial antagonism. This association confirms the primary role of pulcherriminic acid in the antimicrobial antagonism of M. pulcherrima.

Evolution of copper resistance in Xanthomonas euvesicatoria pv. perforans population.

The widespread use of antimicrobials that target bacterial pathogens has driven evolution of resistance, compromising the efficacy of these bactericides. Understanding the emergence and spread of resistance genes via mobile genetic elements is crucial for combating antimicrobial resistance. Copper resistance (CuR) in Xanthomonas euvesicatoria pv. perforans has severely affected the efficacy of copper-based bactericides for controlling bacterial leaf spot disease of tomato and pepper. Here, we investigated the evolutionary pathways of CuR acquisition and dissemination in X. euvesicatoria pv. perforans using an extensive collection of strains. We determined that chromosomally encoded CuR predominates over plasmid-borne CuR in multiple distinct phylogenetic groups of X. euvesicatoria pv. perforans. Our analysis revealed a single site of chromosomal integration by a CuR genomic island, although the genomic island showed sequence variation among phylogenetic groups. While chromosomal CuR was more prevalent, strains with plasmid-borne resistance conferred greater copper tolerance. Additionally, we identified strains carrying two copies of CuR genes, on plasmid and chromosome, that exhibited increased copper tolerance. Strains of X. euvesicatoria pv. perforans from the USA shared identical CuR gene sequences whether on plasmids or chromosome while different alleles were found in strains from other countries. In contrast to X. euvesicatoria pv. perforans, plasmid-borne CuR predominated in closely related pathovar, X. euvesicatoria pv. euvesicatoria. Overall, these findings contribute to a better understanding of the evolution and persistence of CuR in X. euvesicatoria pv. perforans and its closest relatives.IMPORTANCEThe emergence of antimicrobial resistance is a significant threat to agricultural production as it reduces the efficacy of various antimicrobials including copper-based bactericides that are widely used to control plant diseases. The challenge of increasing antimicrobial resistance entering a production system necessitates a deeper understanding of the dynamics and mechanisms by which pathogens acquire resistance. As a result of this research, we have identified different mechanisms of copper resistance acquisition as well as levels of copper resistance in a devastating plant pathogen, X. euvesicatoria pv. perforans. The evolution and dissemination of copper resistance in strains through plasmid or chromosomally integrated genomic island or both presents barriers to current management approaches, where growers rely heavily on copper-based bactericides to manage disease outbreaks. This knowledge is crucial when considering the continued use of existing antimicrobials or adopting alternative antimicrobials in efforts to implement enhanced antimicrobial stewardship strategies in agriculture.

Molecular Biodiversity in Fusarium subglutinans and F. temperatum: A Valuable Tool to Distinguish the Two Sister Species and Determine the Beauvericin Chemotype.

Fusarium subglutinans and F. temperatum are widely distributed maize pathogens recognized as distinct species with a species-specific chemotype based on patterns of mycotoxins. Recent comparative genomic analysis revealed that genomes of both species carry a complete beauvericin (Bea) biosynthetic genes cluster, but the key gene Bea1 in F. subglutinans is not functional likely due to a large insertion (NRPS22ins) and multiple mutations (SNP298 and SNP528). We used the recently published genome sequences for these species to develop PCR markers for investigating the distribution of three main mutations in the Bea1 gene in a large collection of strains of both species from around the world. We also designed a PCR assay for a rapid and reliable discrimination of both species in the evaluation of crop exposure to mycotoxins. Overall, our results showed that SNP528 was the most common mutation, followed by NRPS22ins and SNP298. Moreover, phylogenetic analyses suggest that non-synonymous SNPs have occurred first, and that the resulting inactivation of BEA production has caused the accumulation of other polymorphisms, including the NRPS22ins, in the entire gene-coding region. The screening for genetic differences between these species could guide future crop management strategies.