Test Strains Research Articles

Phenotypic microarray characterization of hemolytic and non-hemolytic strains of Listeria monocytogenes

Limited information is available on the phenotypic characteristics of Listeriamonocytogenes that may affect its virulence of L.monocytogenes. The study focused on comparing the differences between two strains of L. monocytogenes, one hemolytic (LLO+) and one non-hemolytic (tLLO). Using Phenotype Microarray (PM) technology, carbon, nitrogen, and phosphorus-sulfur source utilization by the strains was performed and the KEGG pathway involvement in substrate utilization was analyzed. Of the 285 substrates screened, the results suggested that d-gluconic acid and l-serine may play a role in L. monocytogenes hemolytic activity towards LLO production by generating pyruvate as an intermediate and amino acid biosynthesis, which may play an important role in virulence protein translation. d-gluconic acid and l-serine showed no effect on the tLLO strain in PM analysis and validation tests. Notably, the scope of this study was limited to these two strains of L. monocytogenes. While these findings provide valuable insights into the metabolic differences between hemolytic and non-hemolytic strains, further research is necessary to expand this understanding to a broader range of strains and explore additional factors that may influence LLO functionality.

Improved ductility of hot extruded Mg-0.5Zn-0.5Zr-1RE alloy by Li addition

Mechanical properties of lean Mg-xLi-1RE-0.5Zn-0.5Zr alloys after hot working by the extrusion process were systematically investigated. By increasing Li content, the coarsening of the dynamic recrystallization (DRX) grain size (D) was recorded. This was ascribed to the decrease of the solidus temperature (TSolidus) by increasing Li content, and hence, the increase of the homologous temperature during hot deformation (T/TSolidus). As a result, the tensile yield stress (TYS), ultimate tensile strength (UTS), compressive yield stress (CYS), and ultimate compressive strength (UCS) decreased by increasing Li content. Accordingly, the Hall-Petch relationships of TYS = 145.8 + 69/√D and CYS = 69.3 + 100/√D were proposed, where TYS, CYS, and D are expressed in MPa, MPa, and μm, respectively. However, total elongation in the tension test and fracture strain in the compression test were significantly improved and the crystallographic texture intensity decreased by increasing the Li content. These improvements were found to be quite beneficial for overcoming and breaking the strength–ductility trade-off. The mechanical behavior of these alloys was compared to other competitive alloys for lightweight applications.

ANTIMICROBIAL ACTIVITY OF OILS FROM PUMKIN SEEDS, GRAPE SEEDS AND SEA-BUCKTHORN FRUITs

Currently, the search for new alternative effective sources for obtaining compounds with antimicrobial activity does not lose its relevance. Aim. To investigate the antimicrobial activity of oils obtained by cold pressing from pumpkin seeds, grape seeds and sea-buckthorn fruits. Methods. Antimicrobial activity of oils from pumpkin seeds, grape seeds and sea-buckthorn fruits against strains of indicator microorganisms Staphylococcus aureus АТСС 25923, Micrococcus luteus АТСС 4698, Enterococcus faecalis АТСС 29212, Bacillus subtilis АТСС 6633, Kocuria rhizophila DSM 3480, Escherichia coli АТСС 25922, Proteus vulgaris АТСС 6896, Salmonella enterica NCTC 6017, Klebsiella pneumoniae АТСС 10031, Pseudomonas aeruginosa АТСС 27853, Pseudomonas putida KT 2440 and Candida albicans АТСС 18804 was determined on semi-liquid LB medium by the well method. Results. All tested plant oils showed antimicrobial activity against certain strains of Gram-positive and Gram-negative bacteria, but were ineffective against B. subtilis, P. aeruginosa, P. putida and the eukaryotic microorganism C. albicans. Strains of Gram-positive bacteria were more sensitive to the action of all three types of plant oils. The most sensitive strain was M. luteus ATCC 4698, the size of which zones of no growth exceeded 16 mm under the influence of all tested oils. Pumpkin seeds oil was more effective against sensitive test strains of indicator microorganisms. Conclusions. Plant oils obtained by cold pressing from pumpkin seeds, grape seeds and sea-buckthorn fruits showed variable antimicrobial activity, which was better in pumpkin seeds oil. K. rhizophila DSM 3480 and M. luteus ATCC 4698 strains were the most sensitive to its influence, the sizes of the zones of no growth were 16.5 ± 0.1 mm and 16.3 ± 0.2 mm, respectively. Further researches are necessary to determine the chemical composition and quantitative assessment of the bioactive compounds of these oils, as well as the mechanisms of their action on the cells of microorganisms.

Fungal Bioremediation of the β-Lactam Antibiotic Ampicillin under Laccase-Induced Conditions.

Due to widespread overuse, pharmaceutical compounds, such as antibiotics, are becoming increasingly prevalent in greater concentrations in aquatic ecosystems. In this study, we investigated the capacity of the white-rot fungus, Coriolopsis gallica (a high-laccase-producing fungus), to biodegrade ampicillin under different cultivation conditions. The biodegradation of the antibiotic was confirmed using high-performance liquid chromatography, and its antibacterial activity was evaluated using the bacterial growth inhibition agar well diffusion method, with Escherichia coli as an ampicillin-sensitive test strain. C. gallica successfully eliminated ampicillin (50 mg L-1) after 6 days of incubation in a liquid medium. The best results were achieved with a 9-day-old fungal culture, which treated a high concentration (500 mg L-1) of ampicillin within 3 days. This higher antibiotic removal rate was concomitant with the maximum laccase production in the culture supernatant. Meanwhile, four consecutive doses of 500 mg L-1 of ampicillin were removed by the same fungal culture within 24 days. After that, the fungus failed to remove the antibiotic. The measurement of the ligninolytic enzyme activity showed that C. gallica laccase might participate in the bioremediation of ampicillin.

Plant Growth-Promoting Bacteria Influence Microbial Community Composition and Metabolic Function to Enhance the Efficiency of Hybrid pennisetum Remediation in Cadmium-Contaminated Soil.

The green and efficient remediation of soil cadmium (Cd) is an urgent task, and plant-microbial joint remediation has become a research hotspot due to its advantages. High-throughput sequencing and metabolomics have technical advantages in analyzing the microbiological mechanism of plant growth-promoting bacteria in improving phytoremediation of soil heavy metal pollution. In this experiment, a pot trial was conducted to investigate the effects of inoculating the plant growth-promoting bacterium Enterobacter sp. VY on the growth and Cd remediation efficiency of the energy plant Hybrid pennisetum. The test strain VY-1 was analyzed using high-throughput sequencing and metabolomics to assess its effects on microbial community composition and metabolic function. The results demonstrated that Enterobacter sp. VY-1 effectively mitigated Cd stress on Hybrid pennisetum, resulting in increased plant biomass, Cd accumulation, and translocation factor, thereby enhancing phytoremediation efficiency. Analysis of soil physical-chemical properties revealed that strain VY-1 could increase soil total nitrogen, total phosphorus, available phosphorus, and available potassium content. Principal coordinate analysis (PCoA) indicated that strain VY-1 significantly influenced bacterial community composition, with Proteobacteria, Firmicutes, Chloroflexi, among others, being the main differential taxa. Redundancy analysis (RDA) revealed that available phosphorus, available potassium, and pH were the primary factors affecting bacterial communities. Partial Least Squares Discriminant Analysis (PLS-DA) demonstrated that strain VY-1 modulated the metabolite profile of Hybrid pennisetum rhizosphere soil, with 27 differential metabolites showing significant differences, including 19 up-regulated and eight down-regulated expressions. These differentially expressed metabolites were primarily involved in metabolism and environmental information processing, encompassing pathways such as glutamine and glutamate metabolism, α-linolenic acid metabolism, pyrimidine metabolism, and purine metabolism. This study utilized 16S rRNA high-throughput sequencing and metabolomics technology to investigate the impact of the plant growth-promoting bacterium Enterobacter sp. VY-1 on the growth and Cd enrichment of Hybrid pennisetum, providing insights into the regulatory role of plant growth-promoting bacteria in microbial community structure and metabolic function, thereby improving the microbiological mechanisms of phytoremediation.

Experimental investigation on seismic behaviour of concrete-filled corrugated steel tubes under cyclic torsional loads

Concrete-filled thin-walled galvanized corrugated steel tube (CFCST) is a novel composite member with competitive mechanical behaviour, durability and construction convenience. Several preliminary experimental and numerical works have been conducted on the compressive, flexural, shear, and monotonic torsional performances. However, the unique geometric characteristics of the helical corrugated steel tube (CST) may lead to significant torsional direction-dependent behaviour and complex cyclic torsional working mechanisms, which have not been investigated. This paper therefore presents an experimental investigation of the CFCST under cyclic torsional loads, encompassing the main test variables of member types, diameter-to-thickness ratios, axial compression ratios, and core concrete strengths. The failure modes, hysteretic curves, ductility, energy dissipation capacity, and stiffness degradation are carefully addressed. The cyclic torsional working mechanism of CFCST is discussed through the cyclic test results and strain analysis. The cumulative damage caused by the cyclic torsional loading case is also analysed via the comparisons between the monotonic and cyclic experimental results. The applicability of the existing design methods for the torsional bearing capacity is examined, with specific design suggestions proposed.

Optimization of production and evaluation of Microbial kojic Acid obtained from Sugarcane Molasses (SCM) by Aspergillus sp.

Kojic acid (KA) is an organic acid that is generated by various fungi, particularly by Aspergillus species, as a secondary metabolite. The current study is aimed to determine the optimal conditions for the production of kojic acid from various fungal strains grown on agro-industrial wastes. After testing six fungal strains for their suitability for kojic acid production, Aspergillus oryzae (AUMC.64) and Aspergillus tamari (AUMC.43) were found to be the highest producers of KA. Three different agro-industrial wastes were screened as a fermentation media and sugar cane molasses showed the highest productivity for (KA). Aspergillus oryzae (AUMC.64), and Aspergillus tamari (AUMC.43) achieved the maximal production of kojic acid (25.91, 18.95 ± 0.001 g. L-1respectively) from sugarcane molasses (SCM) under optimum conditions of growth (10% solution of sugarcane molasses, pH 4.0 and fermentation period of 10 days). Also, the antimicrobial activities of KA produced by A. oryzae AUMC64 and A. tamari AUMC43 against the selected test strains of microorganisms Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella typhimurium were recorded. The maximum growth inhibition zone (20–13.2 mm) was observed on the cultures of Escherichia coli. Meanwhile the antioxidant activities of KA produced by A. oryzae AUMC64 and A. tamari AUMC43 was 79.1 and 62.42%, respectively.

Effects of Marquandomyces Marquandii SGSF043 on Maize Growth Promotion and Soil Enzyme Activity

In order to further clarify the growth-promoting effect of the non-core Metarhizium sp. Marquandomyces marquandii on plants, M. marquandii SGSF043, which was obtained via pre-screening in the laboratory, was selected as a test strain and the seed soaking method was adopted. The effects of a fermentation broth obtained from this strain on the seed germination, seedling growth, and rhizosphere soil enzyme activity of maize were studied. The results were as follows: In seed germination tests, M. marquandii SGSF043 fermentation liquid had a certain inhibitory effect on corn seed germination, and the germination rate was only 15%. When the fermentation solution was diluted 10 times, the germination rate reached 97%. After the germination test, the growth of maize plumules was promoted in the groups treated with 10-times and 1000-times dilutions. In the field community experiment, based on the comprehensive evaluation of seedling biomass indicators, the solution diluted 100 times had the best growth-promoting effect. The aboveground fresh weight was increased by 127.13% compared with the control group. The results show that M. marquandii SGSF043 has the potential to promote the growth of maize and improve the soil environment, which provides a theoretical basis for the research on and the application of M. marquandii in farmland.

Modeling test strain data reveal shear damage evolution characteristic of CFRP laminates

CFRP laminates are commonly used in aircraft structures due to their high structural efficiency. The phenomenon-based failures of CFRP laminates have poor predictability for the complex failure process with buckling and matrix fractures. This work carried out seven shear tests of CFRP laminates. It also attempts to reveal its failure characteristic points by directly modeling the measured strain data based on the relative deformation distribution catastrophe. The failure characteristic points are revealed by constructing the stressing state modes/parameters and applying the clustering analysis criterion, whose accuracy can be verified by comparing the shear failure characteristic points of nondestructive/impacted CFRP laminates.

Health Benefits and Antibacterial Properties of Probiotics Isolated From Fermented Food Products

As a result of the continuously expanding scientific evidence probiotic bacteria have become increasingly popular due to their beneficial effects on human health. The main objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from fermented food products as potential probiotics with antimicrobial activity against some test strains. Total four samples of fermented food products were taken (Sauerkraut, Fermented Cucumber, Idli batter and Dosa batter). The Lactic acid bacteria were isolated from these samples and the probiotics were further tested for their ability to tolerate pH, bile salt at different concentrations. The probiotic strains were found to grow at different pH and also at different conc. of bile and NaCl. These isolates exhibited high antibacterial activity when tested against the test organism (Pseudomonas, Streptococcus, Escherichia coli and Klebsiella) in well diffusion method. The present study concludes that the isolated probiotic strain from the fermented food qualifies pH, bile and NaCl tolerance tests that make an isolate to be an ideal probiotic. Probiotic strains were found to carry antimicrobial property and can be used to control gut microbiota. The result of the present study showed that the fermented food products can be used as a good source of probiotic culture.

Pharmaceutical Properties and Phytochemical Profile of Extract Derived from Purple Leaf Graptophyllum pictum (L.) Griff.

Graptophyllum pictum (L.) Griff is a medicinal shrub belonging to the Acanthaceae family and is traditionally used to treat various diseases. Therefore, this study aimed to evaluate the pharmaceutical properties and phytochemical profiles of the methanolic extract of G. pictum. G. pictum leaves was extracted using methanol. Antioxidant, cytotoxic on Michigan Cancer Foundation-7 (MCF-7) and HepG2, antidiabetic, and antibacterial properties were evaluated in vitro. Chemical profile of the extract was identified through qualitative (for phytochemicals), quantitative (for phenolic and flavonoid content), and gas chromatography-mass spectrometry (GC-MS) analysis. The results showed that the extract had potent antioxidant activity against 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals with IC50 values of 49.00 ± 3.20 µg/mL and 70.18 ± 3.27 µg/mL, respectively. It also exhibited cytotoxic effects on human breast (MCF-7) and liver (HepG2) carcinoma cells with growth inhibition percentages of 74.29 ± 1.53% and 64.90 ± 1.94%, respectively. The antidiabetic assay showed that the extract had inhibitory effects on α-glucosidase activity with IC50 value 194.59 ± 15.59 µg/mL, indicating its potential to be developed as an antidiabetic agent. Furthermore, it had antibacterial properties against four test strains, and the highest activity was found against Bacillus subtilis American Type Culture Collection 19659, with minimum inhibitory concentration and minimum bactericidal concentration values of 625 µg/mL and 1250 µg/mL, respectively. Phytochemical tests indicated the presence of alkaloids, flavonoid and terpenoids in the extract, with total phenolic content and total flavonoid content of 41.17 ± 2.38 mg gallic acid equivalents/g and 26.52 ± 0.61 mg quercetin equivalent/g, respectively. GC-MS analysis revealed that it contained several active compounds, including eicosane, 2,4-Di-tert-butylphenol, hentriacontane, tetracosane, octacosane, sulfurous acid, 2-methylhexacosane, docosane, heneicosane, 1-propene-1,2,3-tricarboxylic acid, tributyl ester, and pentacosane. The extract derived from G. pictum leaves was a potential source of therapeutic compounds, particularly for antioxidant, antidiabetic, anticancer, and antibacterial agents.

Effect of laser shock peening on stress corrosion cracking of TC4/2A14 dissimilar metal friction stir welding joints

Stress corrosion cracking (SCC) of welded joints is a significant issue that affects the widespread application of multimetal welded structures in aerospace, transportation, and other fields. This paper investigates the effect of laser shock peening (LSP) on the SCC of TC4/2A14 friction stir welded (FSW) joints with dissimilar metals. The microstructural evolution, mechanical properties, and corrosion behavior with and without LSP treatment were investigated using optical microscopy, transmission electron microscopy, X-ray analysis, electrochemical testing, and slow strain rate tensile testing (SSRT). The results showed that the LSP significantly refined the grains and induced work-hardening on the near-surface of the material. After LSP, the compressive residual stresses on the surface of the titanium and aluminium sides were −817.6 MPa and −153.6 MPa for the joint, respectively. Corrosion resistance was also improved, with the self-corrosion current density on the Al side of the joints reduced by 77% and the SCC susceptibility index (Issrt) reduced from 0.140 to 0.121. The enhanced SCC resistance of the LSP-treated TC4/2A14 dissimilar metal FSW joints is primarily due to grain refinement, work-hardening effect, and high-level compressive residual stress. These factors not only enhance the material strength and improve the pitting resistance of the joints but also prevent the initiation and propagation of SCC.

Evaluation of Two Vaccines against Foot-and-Mouth Disease Used in Transcaucasian Countries by Small-Scale Immunogenicity Studies Conducted in Georgia, Azerbaijan and Armenia.

In countries endemic for foot-and-mouth disease (FMD), routine or emergency vaccinations are strategic tools to control the infection. According to the WOAH/FAO guidelines, a prior estimation of vaccine effectiveness is recommendable to optimize control programs. This study reports the results of a small-scale immunogenicity study performed in Transcaucasian Countries. Polyvalent vaccines, including FMDV serotypes O, A (two topotypes) and Asia1 from two different manufacturers, were evaluated in Georgia, Azerbaijan and Armenia. Naïve large and small ruminants were vaccinated once and a subgroup received a second booster dose. The titers of neutralizing antibodies in sera collected sequentially up to 180 DPV were determined through the Virus Neutralization Test versus homologous strains. This study led to the estimate that both the vaccines evaluated will not induce a protective and long-lasting population immunity, even after a second vaccination, stressing that consecutive administrations of both vaccines every three months are mandatory if one aspires to achieve protective herd immunity.

Features of the vagina microbiotope in patients with adenomyosis

The objective: to assess the composition of the vaginal microbiota in women of reproductive age with adenomyosis.Materials and methods. A comprehensive clinical-laboratory and instrumental prospective examination of 224 patients aged 30 to 50 years (average age – 42.0±1.8 years) with adenomyosis, who were included in the main study group, was conducted. The patients of the main group were divided into 2 subgroups depending on the form of adenomyosis – I group (diffuse form) included 106 women, II group (nodular form) – 118 persons. The control group included 84 healthy women of reproductive age with a regular ovulatory menstrual cycle and no history of gynecological diseases.Patients underwent microscopic examination of vaginal secretions, bacterioscopic examination of vaginal smears, stained according to Gram. Lactobacillus cultures were identified by polymerase chain reaction (PCR) and 16S ribosomal ribonucleic acid analysis.​Results. During the microscopic examination of the vaginal secretion, more than 15 leukocytes in the field of view were detected in 84 (37.5±3.2%) patients of both groups: in 40 (47.9±3.3%) patients of the I group and in 44 (52.1±3.3%) – II group. During the bacterioscopic examination of vaginal swabs, stained according to Gram, no gonococci and trichomonads were found in the main group. Candida fungi were detected microscopically in 158 patients (70.5±3.1%) of the main group: in 71 (66.9±4.6%) of the I group and in 87 (33.1±4.3%) of II group.Genotyping results showed that lactobacilli isolated from women with adenomyosis belonged to seven species: Lactobacillus fermentum, Lactobacillus iners, Lactobacillus gasseri, Lactobacillus amnionii, Lactobacillus jensenii, Lactobacillus crispatus, and Lactobacillus delbrueskii. The majority of lactobacilli strains have high inhibitory activity against all test strains, except for Candida albicans (39 cases, 46.4%). High adhesion to human erythrocytes was determined by 54.7% (46 cases) of the studied cultures.All lactobacilli strains were resistant to metronidazole, 83.3% (70 cases) to kanamycin, 57.1% (48 cases) to vancomycin, all strains were sensitive to roxithromycin, amoxiclav, and ampicillin. Moderate sensitivity to gentamicin and cefazolin was found in 51.9% (43 cases) of cultures, peroxide-forming activity in 80.9% (68 cases).The use of quantitative diagnostic thresholds has led to significant improvements in diagnostic performance. PCR showed 88% sensitivity and 95% specificity for Gardnerella vaginalis and 96% sensitivity and 97% specificity for Atopobium vaginae.Conclusions. It has been established that bacterial vaginosis and microorganisms associated with bacterial vaginosis are independently associated with adenomyosis. The results of the study confirmed that vaginal microorganisms, which are usually diagnosed in women with adenomyosis, ascend to the endometrium from the vagina vertically, which leads to infection of the upper parts of the genital tract.

Evaluation of the Feasibility of Using Commercial Wound Coatings as a Carrier Matrix for Bacteriophages.

Twelve varieties of commercial wound coverings based on biopolymers of natural and synthetic origin, a biological preparation Staphylophag produced by scientific-industrial association Microgen (Russia), registration certificate P N001973/01, and the S. aureus 3196 test strain (GenBank JARQZO000000000) isolated from a patient with a burn wound have been used in our work. The ability of commercial biological wound coatings to absorb solutions was examined by immersing them in a physiological solution (pH 7.0-7.2) followed by weighing. The lytic activity of three bacteriophage series against the test strain was studied using the Appelman method and a spot test. The lytic activity of the bacteriophage in the wound samples was studied within 7 days after its absorption by the wound coatings. The greatest volume of fluid was absorbed by the LycoSorb, NEOFIX FibroSorb Ag, Biatravm, and Chitocol-S wound coatings. All bacteriophage series have been found to have a high lytic activity against the test strain. It has also been shown that Chitocol-S, Collachit-FA, Algipran, and Aquacel Ag Extra possessed their own inherent antibacterial activity under in vitro conditions stable for 7 days; moreover, the lysis zones of the test strain increased after their saturation with bacteriophage. On day 0, a high level of bacteriophage lytic activity with the maximum size of the test strain lysis zones from 49 to 59 mm have been found to remain in all samples of the wound coverings. The bacteriophage activity persisted for 1 day in the samples of Hydrofilm, Polypran, and NEOFIX FibroCold Ag coatings, up to 4 days in Algipran, Nano-Aseptica, and Biatravm coatings; and for 7 days in the Chitocol-S, Collachit-FA, Opsite Post-Op Visible, NEOFIX FibroSorb Ag, Aquacel Ag Extra, and LycoSorb samples. Modern commercial wound dressings based on chitosan-collagen complex (Chitocol-S, Collachit-FA), polyurethane (Opsite Post-Op Visible, LycoSorb, NEOFIX FibroSorb Ag), and Hydrofiber (Aquacel Ag Extra) have a sufficient level of bacteriophage solution absorption, provide a stable preservation of the bacteriophage lytic activity under in vitro conditions up to 7 days. Thus, the in vitro studies prove the possibility of their use as a carrier matrix for bacteriophages.

Comprehensive genomic and plasmid characterization of multidrug-resistant bacterial strains by R10.4.1 nanopore sequencing

The escalating prevalence of multidrug-resistant (MDR) bacteria pose a significant public health threat. Understanding the genomic features and deciphering the antibiotic resistance profiles of these pathogens is crucial for development of effective surveillance and treatment strategies. In this study, we employed the R10.4.1 nanopore sequencing technology, specifically through the use of the MinION platform, to analyze eight MDR bacterial strains originating from clinical, ecological and food sources. A single 72-hour sequencing run could yield approximately 12 million reads which covered a total of 34 gigabases (Gbp). The nanopore R10.4.1 data was processed using the Flye assembler, successfully assembling the genomes of eight bacterial strains and their 18 plasmids. Notably, the assemblies generated solely from R10.4.1 nanopore data closely matched those from next-generation sequencing data. Diverse antibiotic resistance patterns and specific resistance genes in the test strains were identified. Hospital strains that exhibited multidrug resistance were found to harbor various resistance genes that encode efflux pumps and extended-spectrum β-lactamases. Environmental and food sources were found to display resistance profiles in a species-specific manner. The composition of structurally complex plasmids in the test strains could also be revealed by analysis of nanopore long reads, which also suggested evidence of horizontal transfer of plasmids between different bacterial species. These findings provide valuable insights into the genetic characteristics of MDR bacteria and demonstrating the practicality of nanopore sequencing technology for detecting of resistance elements in bacterial pathogens.

Synthesis of iodine-povidone-co-thiazole nanoporous membrane with antibacterial activity and application in water treatment

In order to prevent the spread of the epidemics caused by pathogenic microorganisms, it is very important to explore antimicrobial materials. In this paper, a novel antimicrobial polymer materials with dual active centers, iodine-povidone-co-thiazole nanoporous membrane (IPoTaNm), was successfully synthesized by one-pot emulsion polymerization followed by iodine complexation. The micromorphology and composition were characterized by scanning electron microscope (SEM), Fourier transform infrared spectra (FT-IR), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and contact angle test. Then, its antimicrobial performance was measured by using Escherichia coli and Staphylococcus aureus as test strains. It indicated that IPoTaNm exhibits excellent antibacterial activity, which the inhibition rate got to 99.9 % after 48 h. It also presented sustaining bactericidal activity, which the antimicrobial activity maintained 99.9 % even after >7 days. The synergistic antimicrobial mechanism of thiazole units (AcT) and iodine in IPoTaNm was discussed, and some facters for their inhibitory effects in the water column were investigated. In summary, the obtained IPoTaNm with dual active centers was an excellent candidate for minimizing bacteria-infection in different functional materials, which has potential applications in wastewater treatment to reduce bacterial infections.

Effects of TrPLDs on the pathogenicity of Trichothecium roseum infected apple fruit

Phospholipase D plays a critical regulatory role in the pathogenicity of filamentous fungi. However, the molecular mechanism of PLD regulating the pathogenicity of filamentous fungi has not been reported. In this research, the previously constructed TrPLD1 and TrPLD2 (TrPLDs) mutants were used as test strains. Firstly, the function of TrPLDs in Trichothecium roseum was studied. Then, the effects of TrPLDs on the pathogenicity of T. roseum and the quality of the inoculated apples were verified. The results suggested that the deletion of TrPLD1 delayed the spore germination of ΔTrPLD1 and inhibited germ tube elongation by down-regulating the expressions of TrbrlA, TrabaA and TrwetA. By down-regulating the extracellular enzyme-coding gene expressions, ΔTrPLD1 inhibited the degradation of apple fruit cell wall and the change of fatty acid content during infection, reduced the cell membrane permeability and malondialdehyde (MDA) content of apple fruit, thereby maintaining the integrity of fruit cell membrane, and reduced the pathogenicity of ΔTrPLD1 to apple and kept the quality of apple. However, ΔTrPLD2 did not have a significant effect on the infection process of apple fruit by the pathogen.

A screening study on the detection strain of Coxsackievirus A6: the key to evaluating neutralizing antibodies in vaccines

ABSTRACT The increasing incidence of diseases caused by Coxsackievirus A6 (CV-A6) and the presence of various mutants in the population present significant public health challenges. Given the concurrent development of multiple vaccines in China, it is challenging to objectively and accurately evaluate the level of neutralizing antibody response to different vaccines. The choice of the detection strain is a crucial factor that influences the detection of neutralizing antibodies. In this study, the National Institutes for Food and Drug Control collected a prototype strain (Gdula), one subgenotype D1, as well as 13 CV-A6 candidate vaccine strains and candidate detection strains (subgenotype D3) from various institutions and manufacturers involved in research and development. We evaluated cross-neutralization activity using plasma from naturally infected adults (n = 30) and serum from rats immunized with the aforementioned CV-A6 strains. Although there were differences between the geometric mean titer (GMT) ranges of human plasma and murine sera, the overall trends were similar. A significant effect of each strain on the neutralizing antibody test (MAX/MIN 48.0 ∼16410.3) was observed. Among all strains, neutralization of the S112 strain by 15 different sera resulted in higher neutralizing antibody titers (GMTS112 = 132.0) and more consistent responses across different genotypic immune sera (MAX/MIN = 48.0). Therefore, S112 may serve as a detection strain for NtAb testing in various vaccines, minimizing bias and making it suitable for evaluating the immunogenicity of the CV-A6 vaccine.

Pre-clinical safety and toxicity assessment of Limosilactobacillus fermentum NCDC 400 in murine model

Comprehensive safety assessment of potential probiotic strains is crucial in the selection of risk-free strains for clinical translation. This study aimed to evaluate the biosafety of Limosilactobacillus fermentum NCDC 400, a potential probiotic strain, using oral toxicity tests in a Swiss albino mouse model. Mice were orally gavaged with low (108 CFU/mouse/day) and high (1010 CFU/mouse/day) doses of NCDC 400 for 14 (acute), 28 (subacute), and 90 (subchronic) days to assess behavioral, hematological, biochemical, immunological, and histological effects. The administration of NCDC 400 did not result in any observable adverse effects on general health parameters, including body weight, feed and water intake, and organ indices. Hematological and biochemical parameters, such as glucose, serum enzymes, urea, creatinine, serum minerals, total serum proteins, and lipid profile, remained largely unaffected by the test strain. Notably, NCDC 400 administration led to a significant reduction in harmful intestinal enzymes and improvement in gut health indices, as indicated by fecal pH, lactate, ammonia, and short-chain fatty acids. There were no instances of bacterial translocation of NCDC 400 to blood or extra-intestinal organs. Immune homeostasis was not adversely affected by repeated exposure to NCDC 400 in all three oral toxicity studies. Histopathological examination revealed no strain-related changes in various tissues. Based on these findings, a dose of 1010 CFU/mouse/day was considered as the No Observable Effect Level (NOEL) in healthy mice. In conclusion, this study demonstrates the safe and non-toxic behavior of L. fermentum NCDC 400. The results support and ensure the safety and suitability for clinical trials and eventual translation into clinical practice as potential probiotic.