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The fruit extract of Buchanania obovata and the eutectic-based ionic liquid were utilized, in an eco-friendly, inexpensive, simple method, for synthesizing zinc oxide nanoparticles (ZnO NPs). The influence of the reducing, capping and stabilizing agents, in both mediums, on the structure, optical, and morphological properties of ZnO NPs was extensively investigated. The surface plasmon resonance peaks were observed at 340 nm and 320 nm for the fruit-based and the eutectic-based ionic liquid mediums, respectively, indicating the formation of ZnO NPs. XRD results confirmed the wurtzite structure of the ZnO NPs, exhibiting hexagonal phases in the diffraction patterns. The SEM and TEM images display that the biosynthesized ZnO NPs exhibit crystalline and hexagonal shape, with an average size of 40 nm for the fruit-based and 25 nm for the eutectic-based ionic liquid. The Brunauer–Emmett–Teller (BET) surface area analysis, revealed a value ∼13 m2 g−1 for ZnO NPs synthesized using the fruit extract and ∼29 m2 g−1 for those synthesized using the eutectic-based ionic liquid. The antibacterial activity of the biosynthesized ZnO NPs was assessed against clinically isolated Gram-negative (E. coli) and Gram-positive (S. aureus) bacterial strains using the inhibition zone method. The ZnO NPs produced from the eutectic-based ionic liquids confirmed superior antibacterial activity against both S. aureus and E. coli compared to those mediated by the utilized fruit extract. At a concentration of 1000, the eutectic-based ionic liquid mediated ZnO NPs displayed a maximum inhibition zone of 16 mm against S. aureus, while against E. coli, a maximum inhibition zone of 15 mm was observed using the fruit extract mediated ZnO NPs. The results of this study showed that the biosynthesized ZnO NPs can be utilized as an efficient substitute to the frequently used chemical drugs and covering drug resistance matters resulted from continual usage of chemical drugs by users. [ABSTRACT FROM AUTHOR]

Electrospinning has garnered much attention for skin renewal, emphasizing skin's pivotal role as a primary protective layer and the susceptibility to loss caused by burns. The research aimed to develop a multipurpose wound dressing that safeguard injuries and facilitates the renewal of dermal tissues. Two-layer nanofibers were prepared using polyvinyl alcohol–chitosan–gelatin/polyacrylonitrile (PVA–CS–Gel/PAN), containing mupirocin (Mu 3% w/w) in underlying layer and silver nanoparticles (AgNps) in the upper layer with varying concentrations. AgNps were synthesized from Capsella bursa-pastoris extract by the green method and characterized using XRD, SEM, FTIR, and UV techniques. Then, PVA–CS–Gel/PAN solutions with AgNps and Mu were electrospun into multilayer dressings. The effectiveness of the nanofibers was evaluated through in vitro and in vivo tests. The study examined the nanofibers containing spherical AgNps with an average diameter of 72.57 nm and a negative surface charge (− 12 mv). They had uniform and smooth surfaces with a diameter range of 476.31 to 926.04 nm. According to swelling and contact angle results, hydrophilicity of samples had a direct relation with water absorption. Controlled drug release within 72 h followed Higuchi or first-order profiles. MTT and antibacterial analyses indicated that optimized nanofibers (Mu/1% AgNps) had suitable biocompatibility and synergistic potential against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. Additionally, an in vivo test on rats with second-degree burns after 28 days demonstrated a 98.97% improvement in revival, outperforming its commercial counterparts. Consequently, the results position the designed composite nanofiber as a promising candidate for wound healing applications, aiding in enhancing skin regeneration. [ABSTRACT FROM AUTHOR]

Recently, cesium lead halide perovskites such as CsPb 2 Br 5 and CsPbBr 3 have drawn the attention of researchers because of their unique optical, electronic, and chemical properties. To improve the photo and/or chemical performance of such CsPb 2 Br 5 (termed as CPB hereafter), we have realized multiple facile routes for its combination with UV-active TiO 2 nanoparticles. Resultantly developed binary nanocomposites of TiO 2 , CPB perovskites and TiO 2 /CPB-nanocomposite (TiO 2 /CPB-NC) offered a meaningful photochemical contrast between pseudo-successive ionic layer adsorption and reaction (p -SILAR) and electrostatic self-assembly methods for targeting photocatalytic degradation of toxic dyes under solar irradiation and resulted significant performance as reactant for oxygen evolution (OER) as revealed by extensive electrochemical impedance spectroscopy (EIS). In parallel to extensive material-based characterization using SEM, XRD, and UV Vis. etc, the study was further extended to the theoretical investigation of the structure of CsPb 2 Br 5 , and antibacterial activity against gram-positive and gram-negative bacteria namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). RhB degradation of TiO 2 increased from 13% to 58% by deposition of CPB, in parallel to 100% inhition zone growth. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Bacteria-associated infections and thrombus formation are the two major complications plaguing the application of blood-contacting medical devices. Therefore, functionalized surfaces and drug delivery for passive and active antifouling strategies have been employed. Herein, we report the novel integration of bio-inspired superhydrophobicity with nitric oxide release to obtain a functional polymeric material with anti-thrombogenic and antimicrobial characteristics. The nitric oxide release acts as an antimicrobial agent and platelet inhibitor, while the superhydrophobic components prevent non-specific biofouling. Widely used medical-grade silicone rubber (SR) substrates that are known to be susceptible to biofilm and thrombus formation were dip-coated with fluorinated silicon dioxide (SiO 2) and silver (Ag) nanoparticles (NPs) using an adhesive polymer as a binder. Thereafter, the resulting superhydrophobic (SH) SR substrates were impregnated with S -nitroso- N -acetylpenicillamine (SNAP, an NO donor) to obtain a superhydrophobic, Ag-bound, NO-releasing (SH-SiAgNO) surface. The SH-SiAgNO surfaces had the lowest amount of viable adhered E. coli (> 99.9 % reduction), S. aureus (> 99.8 % reduction), and platelets (> 96.1 % reduction) as compared to controls while demonstrating no cytotoxic effects on fibroblast cells. Thus, this innovative approach is the first to combine SNAP with an antifouling SH polymer surface that possesses the immense potential to minimize medical device-associated complications without using conventional systemic anticoagulation and antibiotic treatments. [ABSTRACT FROM AUTHOR]

N -doped carbon nanosheets were synthesized to reveal wide-spectrum photocatalytic H 2 O 2 generation. After the loading of Fe ions, they reveal the enhanced water disinfection ability via photocatalytic cascade. [Display omitted] The pervasive presence of pathogenic bacteria in water environment poses a serious threat to public health. Here, a photocatalytic cascade was developed to reveal great water disinfection. Firstly, N -doped carbon nanosheets (N -CNSs) about 30–50 nm in size were synthesized by a hydrothermal strategy. It revealed wide-spectrum photocatalysis for H 2 O 2 generation via a typical two-step single-electron process. A Fenton agent (Fe ion) was loaded, N -CNSs-Fe can in-situ convert photocatalytic H 2 O 2 into ·OH with high oxidation potential. Moreover, its Fenton active is three times greater than pure Fe2+ owing to electron enrichment from N -CNSs to Fe for Fe3+/Fe2+ cycle. Further investigation displayed that Fe loading also could decrease bad gap and promote charge separation to boost photocatalysis. In addition, N -CNSs-Fe possesses positive surface potential to exhibit strong interaction with negative bacteria, facilitating the capture. Therefore, the nanocomposite can effectively inactivate E. coli with a lethality rate of 99.7 % under stimulated sunlight irradiation. In addition, it also was employed to treat a complex lake water sample, revealing great antibacterial (95.1 %) and dye-decolored (92.3 %) efficiency at the same time. With novel biocompatibility and antibacterial ability, N -CNSs-Fe possessed great potential for water disinfection. [ABSTRACT FROM AUTHOR]

The tailor-made synthetic sRNA-based gene expression knockdown system has demonstrated its efficacy in achieving pathway balancing in microbes, facilitating precise target gene repression and fine-tuned control of gene expression. This system operates under a competitive mode of gene regulation, wherein the tailor-made synthetic sRNA shares the intrinsic intracellular Hfq protein with other RNAs. The limited intracellular Hfq amount has the potential to become a constraining factor in the post-transcription regulation of sRNAs. To enhance the efficiency of the tailor-made sRNA gene expression regulation platform, we introduced an Hfq expression level modulation-coordinated sRNA-based gene knockdown system. This system comprises tailor-made sRNA expression cassettes that produce varying Hfq expression levels using different strength promoters. Modulating the expression levels of Hfq significantly improved the repressing capacity of sRNA, as evidenced by evaluations with four fluorescence proteins. In order to validate the practical application of this system, we applied the Hfq-modulated sRNA-based gene knockdown cassette to Escherichia coli strains producing 5-aminolevulinic acid and L-tyrosine. Diversifying the expression levels of metabolic enzymes through this cassette resulted in substantial increases of 74.6% in 5-aminolevulinic acid and 144% in L-tyrosine production. Tailor-made synthetic sRNA-based gene expression knockdown system, coupled with Hfq copy modulation, exhibits potential for optimizing metabolic fluxes through biosynthetic pathways, thereby enhancing the production yields of bioproducts. • sRNA system suppresses gene expression, utilizing intrinsic Hfq proteins shared with other RNAs. • Adjusting the Hfq quantity facilitates effective repression of gene expression through sRNA. • The application showed elevated 5-aminolevulnic acid (74.6%) and L-tyrosine (144%) production. [ABSTRACT FROM AUTHOR]

The introduction of oxygen defects in semiconductor electronic structures is considered to be an effective strategy to improve their photocatalytic activity. In this work, rare-earth Er3+−doped BiOBr (Er/BiOBr) with oxygen-rich vacancies (OVs) was prepared via simple hydrothermal method. Compared with pure BiOBr, Er/BiOBr has a narrower band gap and more abundant OVs, which together improve the separation efficiency of photogenerated carriers. The introduction of Er not only creates impurity states between conduction band (CB) and valence band (VB), but also produces more OVs as electron traps. Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were used as evaluation systems for these materials with different Er3+ doping contents. The results showed that under the combined action of ·O 2 − and H 2 O 2 , 2.0% EBB samples with Er3+ doping content of BiOBr showed the best broad-spectrum antibacterial activity, and E. coli and S. aureus were completely inactivated at 0.03 mg ml−1 and 0.05 mg ml−1 concentrations. The surface and interfacial structures of Er/BiOBr samples were studied by XRD, brunauer-emmet-teller method, SEM, TEM and EDX. OVs and photogenerated carrier separation in Er/BiOBr were determined by ESR, PL and photochemical detection methods. More importantly, through the detection of lipid peroxidation and bacterial respiratory chain dehydrogenase activities, the internal and external processes of ROS on bacterial inactivation were determined, and the photocatalytic antibacterial mechanism was summarized. This study for the antimicrobial properties of rare earth ions doped improve photocatalytic materials provides a new train of thought. [ABSTRACT FROM AUTHOR]

[Display omitted] • Perturbing O-antigen ligation shortened the resuscitating lag phase. • Higher ATP levels of Δ rfaL VBNC cells promote resuscitation. • ATP consumption during lag phase was highly correlated with resuscitation efficiency. • ATP was utilized to activate the Handler and salvage pathways to synthesize NAD+. • VBNC cells using residual ATP recover metabolic activity, driving cells to exit dormancy. Entry into the viable but nonculturable (VBNC) state is a survival strategy adopted by bacteria to survive harsh environment. Although VBNC cells still have metabolic activity, they lose the ability to form colonies on nonselective culture media. Thus, conventional bacterial detection methods, such as plate counting, are unable to detect the presence of VBNC cells. When the environmental conditions are appropriate, VBNC cells can initiate resuscitation, posing a great risk to the safety of public health. The study of the VBNC resuscitation mechanism could provide new insights into the prevention and control of VBNC resuscitation. Uncovering the molecular mechanism of VBNC cell resuscitation by investigating the role of O-antigen ligase (RfaL) in inhibiting the resuscitation of Escherichia coli O157:H7 in the VBNC state. RfaL was screened and verified as a resuscitation inhibitor of VBNC Escherichia coli O157:H7 by detecting resuscitation curve and time-lapse microscopy. The mechanism of RfaL impacts VBNC E. coli resuscitation was investigated by detecting the single cell ATP content, metabolomic changes, NAD(H) content and new protein biosynthesis of WT and Δ rfaL at different stage of resuscitation. Mutation of rfaL , which encoded an O-antigen ligase, markedly shortened the resuscitating lag phase. Further studies indicated that Δ rfaL VBNC cells contained higher ATP levels, and ATP consumption during the resuscitating lag phase was highly correlated with resuscitation efficiency. Metabolomic analysis revealed that ATP was utilized to activate the Handler and salvage pathways to synthesize NAD+, balancing redox reactions to recover cell activity and promote cell resuscitation. Our findings revealed a strategy employed by VBNC cells for revival, that is, using residual ATP to primarily recover metabolic activity, driving cells to exit dormancy. The synthesis pathway of lipopolysaccharide (LPS) in rfaL null mutant was inhibited and could supply more ATP to synthesis NAD+ and promote resuscitation. [ABSTRACT FROM AUTHOR]

Les infections bactériennes graves ont une incidence plus élevée dans la période néonatale qu'à tout autre âge pédiatrique et leur gravité est accrue en l'absence de diagnostic et de traitement précoces. L'incidence est encore plus importante chez les prématurés que chez les nouveau-nés à terme. Les signes cliniques induits sont peu spécifiques et parfois insignifiants, et les biomarqueurs sont peu performants au cours des 24 premières heures de l'infection. Pendant des décennies, cette situation a conduit à traiter trop d'enfants, pendant de longues périodes, avec des antibiotiques à large spectre. Aujourd'hui, le défi consiste à prescrire des traitements ciblés en identifiant les nouveau-nés réellement infectés. Au cours de ces dix dernières années, nous avons assisté à des changements de paradigme majeurs dont il est essentiel de tenir compte. En effet, la prise de conscience croissante de l'impact écologique de l'antibiothérapie précoce, notamment sa contribution à la résistance de certaines bactéries aux antibiotiques, implique de choisir l'antibiotique à spectre le plus étroit et des durées de traitement en adéquation réelle avec les signes d'infection. Parmi les tests biologiques, les plus importants sont les hémocultures. Au moins une hémoculture, réalisée dans des conditions d'asepsie, de volume suffisant (1 à 2 mL) et avec des flacons pédiatriques, doit être effectuée dès que la décision de traiter est prise, avant de débuter toute antibiothérapie. Les bactéries responsables des infections bactériennes néonatales précoces (IBPN) n'ont pas évolué de manière significative au cours des dernières années et restent dominées par les Streptocoques du groupe B et Escherichia coli , qui sont les principales cibles du traitement. Le SGB est largement prédominant chez les enfants nés à terme, mais la proportion d'infections dues à E. coli augmente avec la prématurité. Severe bacterial infections have a higher incidence in the neonatal period than at any other pediatric age. Incidence is even higher in premature babies than in term newborns, and severity is increased in the absence of early diagnosis and treatment. By contrast, clinical signs are nonspecific and sometimes trivial, and biomarkers perform poorly during the first 24 hours of infection. For decades, this has led to having too many children treated for extended periods with broad-spectrum antibiotics. Today, the challenge is to prescribe antibiotics in a targeted way, by identifying truly infected newborns. Over the last ten years, major paradigm shifts have occurred and should be taken into account, as a result of growing awareness of the ecological impact of early antibiotic therapy, notably antibiotic resistance, by choosing the narrowest spectrum antibiotic and stopping antibiotic therapy as soon as the diagnosis of infection has been reasonably ruled out. Among the biological tests, the most important are blood cultures. At least one blood culture, taken under aseptic conditions, of sufficient volume (1 to 2 mL), and using pediatric bottles must be taken as soon as the decision to treat has been made, before starting any antibiotic therapy. The bacteria responsible for early-onset bacterial neonatal infections (EBNI) have not changed significantly over recent years and remain dominated by Group B streptococcus and Escherichia coli , which are the main targets of treatment. GBS is largely predominant in full-term infants, but the proportion of infections due to E. coli increases with prematurity. [ABSTRACT FROM AUTHOR]

Escherichia coli FocA and FocB formate channels export formate or import it for further disproportionation by the formate hydrogenlyase (FHL) complex to H 2 and CO 2. Here, we show that under pH and osmotic stress FocA and FocB play important roles in regulating proton and potassium fluxes and couple this with H 2 production in stationary-phase cells. Using whole-cell assays with glucose as electron donor, a focB mutant showed a 50 % decrease in V H2 , while N'N' -dicyclohexylcarbodiimide (DCCD) treatment of osmotically stressed cells underlined the role of F O F 1 ATPase in H 2 production. At pH 7.5 and under osmotic stress FocB contributed to the proton flux but not to the potassium flux. At pH 5.5 both formate channels contributed to the proton and potassium fluxes. Particulalry, a focA mutant had 40 % lower potassium flux whereas the proton flux increased approximately two-fold. Moreover, at pH 5.5H 2 production was totally inhibited by DCCD in the focA mutant. Taken together, our results suggest that depending on external pH, the formate channels play an important role in osmoregulation by helping to balance proton/potassium fluxes and H 2 production, and thus assist the proton F O F 1 -ATPase in maintenance of ion gradients in fermenting stationary-phase cells. [Display omitted] • At pH 7.5 and under osmotic stress FocB contributed to the proton flux but not to the potassium flux. • At pH 5.5 both formate channels contributed to the proton and potassium fluxes. • At low pH H 2 production was totally inhibited by DCCD in the focA mutant. [ABSTRACT FROM AUTHOR]

Urban surface water is increasingly used for contact recreation. Predicting Escherichia coli (E. coli) concentrations in these waters can support early warning of bathers and explain the dynamics of this faecal pollution indicator. This study provides the first overview of the scientific knowledge on E. coli prediction models for freshwater in cities. Modelling techniques for urban waters are comparable to those for other freshwater environments, with multiple linear regression being the most frequently used approach. While previously reviewed E. coli prediction models for freshwater beaches predominantly target lakes, urban models mainly target rivers. We found indications that model performance for urban rivers is lower than for recreational beach water in rivers in general. Reported performance metrics indicate that not all relevant sources are captured by the models. Future research should solve the lack of insight into model performance for specific applications and verify the suggested directions to improve models' accuracy. [ABSTRACT FROM AUTHOR]

Bacteria produce and release small signal molecules, autoinducers, as an indicator of their cell density. The system, called a quorum-sensing (QS) system, is used to control not only virulence factors but also antibiotic production, sporulation, competence, and biofilm formation in bacteria. Different from antibiotics, QS inhibitors are expected to specifically repress the virulence factors in pathogenic bacteria without inhibiting growth or bactericidal effects. Therefore, since QS inhibitors have little risk of antibiotic-resistant bacteria emergence, they have been proposed as promising anti-bacterial agents. In the present study, we aimed to find new QS inhibitors that prohibit the signaling cascade of autoinducer 3 (AI-3) recognized by a QseCB two-component system that regulates some virulence factors of pathogens, such as enterohemorrhagic Escherichia coli (EHEC) and Salmonella enterica subsp. enterica serovar Typhimurium. We have established the method for QS-inhibitor screening using a newly constructed plasmid pLES-AQSA. E. coli DH5α transformed with the pLES-AQSA can produce β-galactosidase that converts 5-bromo-4-chloro-3-indolyl β-d-galactopyranoside (X-gal) into blue pigment (5-bromo-4-chloro-indoxyl) under the control of the QseCB system. By screening, Heyndrickxia coagulans (formerly Bacillus coagulans) 29-2E was found to produce an exopolysaccharide (EPS)-like water-soluble polymer that prohibits QseCB-mediated β-galactosidase production without antibacterial activities. Further, the simultaneous injection of the 29-2E strain significantly improves the survival rate of Salmonella Typhimurium-infected silkworm larvae (from 0% to 83.3%), suggesting that the substance may be a promising inhibitor against the virulence of pathogens without risk of the emergence of antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

Some strains of nonpathogenic Allorhizobium vitis can control crown gall disease in grapevines caused by pathogenic A. vitis and are considered candidates for biocontrol agents. Many plant pathogenic bacteria regulate the expression of their virulence genes via quorum sensing using N -acylhomoserine lactone (AHL) as a signaling compound. The eight nonpathogenic A. vitis strains used in this study showed AHL-degrading activity. The complete genome sequence of A. vitis MAFF 212306 contained three AHL lactonase gene homologs. When these genes were cloned and transformed into Escherichia coli DH5α, E. coli harboring the aiiV gene (RvVAR031_27660) showed AHL-degrading activity. The aiiV coding region was successfully amplified by polymerase chain reaction from the genomes of all eight strains of nonpathogenic A. vitis. Purified His-tagged AiiV exhibited AHL lactonase activity by hydrolyzing the lactone ring of AHL. AiiV had an optimal temperature of approximately 30 °C; however, its thermostability decreased above 40 °C. When the AiiV-expressing plasmid was transformed into Pectobacterium carotovorum subsp. carotovorum NBRC 3830, AHL production by NBRC 3830 decreased below the detection limit, and its maceration activity, which was controlled by quorum sensing, almost disappeared. These results suggest the potential use of AHL-degrading nonpathogenic A. vitis for the inhibition of crown gall disease in grapevines and other plant diseases controlled by quorum sensing. [ABSTRACT FROM AUTHOR]

This study proposed an innovative approach to the development of sustainable and biodegradable food packaging materials by incorporating inexpensive nano-silica (SiO2NPs) in designed hydrogel (CSG) film employing biodegradable polymers: synthetic polymer polyvinyl alcohol (PVA), natural polymer - carboxymethyl cellulose (CMC) and protein-based bio-polymer –gelatine, and a commercial crosslinker, tetraethoxysilane (TEOS) through a conventional air-dry casting technique. The CSG hydrogel blends were modified with varying amounts of SiO2NPs (0.05g, 0.1g, 0.15g and 0.2g) and compared with the blend without SiO2NPs to determine the effect of SiO2NPs loading through various characterisation techniques and applications including antioxidant and antimicrobial activity. Comprehensive characterizations of the CSG films revealed that CSG 0.1 (containing 0.1g SiO2NPs) exhibited the most favourable functional properties, low crystallinity, high flexibility, suitable pore size, thermal stability, adequate tensile strength, elongation at the breaking point and maximum stability by swelling and diffusion test. The addition of SiO2NPs consistently enhanced thermal and mechanical stability in all CSG films. Further, these CSG films were implemented for antioxidant test and antimicrobial activity against gram-positive Bacillus cereus and gram-negative Escherichia coli. SiO2NPs integration significantly elevated the antioxidant capacity in all films, with CSG 0.1 showing ⁓7% improvement. The antimicrobial activity of SiO2NPs-modified CSG films was also notable, with CSG 0.1 effectively inhibiting B. cereus by 1.2cm zone and E. coli by 0.5cm zone. A soil burial test was performed to pattern the biodegradability of CSG hydrogels. Therefore, the outstanding improvements in the intrinsic properties of CSG films, owing to SiO2NPs modification, positioned these CSG hydrogels as promising candidates for advanced food packaging materials in various industries. [ABSTRACT FROM AUTHOR]

The preparation of manganese substituted iron oxide magnetic nanoparticles by polyol synthesis route. Due to the unique properties, diethylene glycol (DEG) and tri-ethylene glycol (TEG) used as a solvent in synthesis method with different volumetric variations. The structural, morphological and hyperthermic properties of prepared samples are investigated. Formation of single-phase cubic spinel lattice for all compositions confirmed by X-ray diffraction and crystallite size was found to be decreased from 20.6 ± 1.3 to 15.2 ± 1.7 nm with varying ratio of DEG/TEG. Transmission electron microscopy (TEM) analysis displayed spherical grains with an agglomeration of the MnFe2O4 magnetic nanoparticles (MNPs). Heating ability of MNPs studied with an induction heating system under different magnetic field strengths at 20 kA/m and 26.6 kA/m by varying nanoparticle concentrations at fixed frequency of 278 kHz. Antimicrobial activity on E. coli and antifungal activity on C. albicans showed effectiveness of MNPs at 10 mg/mL for such activities. Additionally, ROS induction in presence of MNPs illustrates probable action against E. coli and C. albicans and as antibacterial and antifungal agent in the medical field due to ROS generation ability.It has been shown that these optimized MNPs will play multifaceted roles for magnetic hyperthermia therapy as heat mediators, and antibacterial/antifungal agents owing to their magnetic induction heating properties and biological activities. [ABSTRACT FROM AUTHOR]

This research aimed to prepare wheat gluten-based films activated by free and encapsulated L. majorana Origanum essential oil (MEO). Tween 80 and whey protein isolate were utilized to prepare MEO-loaded nanoemulsion (NE) and Pickering emulsion (PE), respectively. PE and NE had particle sizes of 186.7 nm and 149.5 nm, respectively. The NE had lower zeta potential and higher encapsulation efficiency. After incorporation of the obtained nanocapsules and free MEO into the gluten films at three levels (1, 3 and 5 wt%), the morphological, physical, antioxidant and antibacterial characteristics of the active films were assessed. According to the FE-SEM analysis, the surface roughness of films increased by adding free MEO and nanocapsules. XRD test revealed that the free MEO causes a decrease in the crystallinity of the film, but its encapsulated forms had no adverse effect. Improving the thermal properties of gluten films after the incorporation of PE-MEO nanocarriers was approved by TGA analysis. Adding free and encapsulated MEO led to an increase in the water solubility of films and a decrease in the WVP. The weakening effect of MEO on the mechanical characteristics of gluten films was the lowest when the PE nanocapsules were incorporated. The antioxidant activity of the films increased significantly (p < 0.05) with the addition of free and encapsulated MEO. However, the encapsulation slightly decreased the antibacterial potential of MEO against E. coli and S. aureus. To conclude, the produced active gluten film with encapsulated MEO, especially the PE one, presented considerable potential for use as active food packaging. [ABSTRACT FROM AUTHOR]

Escherichia coli in phosphate-buffered saline was treated with high hydrostatic pressures (HHPs) of 400, 500, and 600 MPa at 25 °C for 10 min. The cell suspension was then plated on nonselective agar and incubated at 20, 25, 30, 35, 37, and 40 °C to study the effect of the incubation temperatures on the detection of HHP-injured populations. The number of detected cells was maximum when incubated at 25 °C for 72 h. Cold storage at 4 °C for 7 d after HHP-treatment improved the detection efficacies of incubations at 30–40 °C, implicating increased tolerance of HHP-injured cells against the mild heat. Combined incubation at 25 °C for more than 6 h with subsequent incubation at 35 °C shortened total incubation period from 72 h to 24 h while achieving the maximized colony number obtained by the incubation at 25 °C for 72 h. [ABSTRACT FROM AUTHOR]

A modified method for culturing, concentrating, and purifying phage ϕ24B preparations was developed. In particular, a new lysogenic phage-producing strain lacking flagella was used, induction conditions were optimized, and purification in a sucrose gradient followed by concentration by deposition on a Freon 113 cushion were used. Using this method, a preparation of the Stx-converting bacteriophage ϕ24B was obtained, suitable for CryoEM direct analysis. Based on CryoEM data for this phage, the first primary three-dimensional reconstruction of its virions was performed. The structure of the phage ϕ24B tail is described. It was shown that the adsorption apparatus of this virus is represented by six thin lateral fibrils, and an axial fibril located at the end of the tail. This arrangement of the tail structure is consistent with the previously proposed hypothesis based on analysis of the receptor binding proteins (RBPs) of this bacteriophage. [ABSTRACT FROM AUTHOR]

Weeds, which are often-overlooked inhabitants of our ecosystems, play a remarkable role as hidden reservoirs and unconventional breeding grounds for novel viruses. Nevertheless, their importance is often underestimated in the field of biodiversity studies. Here, we report the complete nucleotide sequence, phylogenetic analysis and recombination pattern of a novel begomovirus associated with yellow vein diseases of Croton bonplandianum. During a survey conducted in August 2016, C. bonplandianum plants with severe leaf curl and yellow vein symptoms were identified at Trichy, Tamil Nadu, India. Total genomic DNA was isolated from symptomatic leaf samples by using the CTAB method, and begomovirus universal primers were used to confirm the presence of begomovirus via PCR. The samples were amplified using rolling circle amplification (RCA) followed by restriction digestion to yield ~ 2.7 Kb fragment unit length of begomoviruses. Full-length fragments ligated with pUC19 vector were transformed to E. coli, and the recombinant clones were confirmed by colony PCR and restriction digestion. The complete genome sequence obtained for the clone WK3 contained 2773 bp and showed a highest nucleotide sequence identity of 89.62% and 89.26% with papaya leaf curl virus (PaLCuV) (MK087120) and bhendi yellow vein Bhubaneswar virus (BYVBhV) (FJ589571), respectively. In phylogenetic analysis, WK3 sequence formed a separate clade with BYVBhV. Recombination analysis indicated the putative evolution of the newly characterized begomovirus isolate WK3 through frequent recombination of parental sequences tomato leaf curl Iran virus (ToLCIRV) and BYVBhV in the background of CroYVMV. Based on the current ICTV criteria for the demarcation of begomoviruses species threshold (< 91%), this is identified as a member of new virus species for which the name "Croton yellow vein leaf curl virus" is proposed based on its symptom morphology. [ABSTRACT FROM AUTHOR]

Ridge gourd (Luffa acutangula L. Roxb.) is one of the most important vegetable crops in India. It belongs to the family Cucurbitaceae; like any other crop, it is also highly susceptible to biotic and abiotic stresses. Among the biotic stresses, tomato leaf curl New Delhi Virus (ToLCNDV) is becoming a major constraint in cultivation of ridge gourd. ToLCNDV is naturally transmitted through whitefly in a circulative and persistent manner and causes the yield loss to the tune of 40–100% (Patil et al. in Virus Dis 28(2):146–155, 2017. https://doi.org/10.1007/s13337-017-0376-6). In present investigation, coat protein gene of ToLCNDV was used to construct a phylogenetic tree showing no host-specificity in the population studied. Further, for in vitro expression studies, the coat protein gene was cloned into pET28a and successfully overexpressed in E. coli BL21 (DE3) cells. The expression of recombinant coat protein varied with different induction time and the highest expression was recorded in 4 h of induction period, incubated with 1-mM IPTG at 37 °C. Overexpressed protein was further purified using Ni–NTA column and confirmed through SDS-PAGE analysis. The present study will help to develop ELISA-based detection tools to diagnose the disease as well as to take up immediate management practices. [ABSTRACT FROM AUTHOR]

The application of antibiotic medicine to save numerous lives is in jeopardy due to the alarming elevation in antibiotic-resistant organisms as a consequence of improper and imprudent usage of antibiotics. This study investigated the antibacterial efficacy of pelargonidin (PG) by employing a cost-effective nano-formulation-based targeted drug delivery system as an alternative to conventional strategies. The precise targeting of bacteria was made easier by synthesizing nano-particles of phyto-product pelargonidin (NPG) by employing poly-lactide-co-glycolide (PLGA), a biodegradable polymer. The physico-chemical characterization of NPGs was performed via AFM study and the antibacterial efficacy of NPGs tested against Escherichia coli and Staphylococcus aureus was assessed by agar disc diffusion method. Additionally, the docking platform explored in this study enabled the prediction of the ability of PG to occupy the binding pocket of EF-Tu (elongation factor thermo unstable), a vital bacterial protein that operates on a translational level. The overall results implicate that NPG was an effective drug candidate against the gram-negative bacteria E. coli and the gram-positive bacteria S. aureus according to the diameter of the inhibition zone (23 ± 0.82 mm: E. coli and 22.67 ± 1.25 mm: S. aureus). Furthermore, in silico analysis revealed that the NPG-EF-Tu complex had an excellent docking score of −9.13 Kcal/mol, indicating key amino acid residues required for interaction, and anticipating the signaling component/s involved that may be hindered by NPG, thereby leading to a decline of bacterial growth. The core phyto-compound of NPG (pelargonidin) could effectively bind to EF-Tu thereby exercising strong antimicrobial efficacy against both E. coli and S. aureus making it a potential alternative to the usage of commercial antibacterials with a history of drug-resistance. [ABSTRACT FROM AUTHOR]

Shake-flask culture, an aerobic submerged culture, has been used in various applications involving cell cultivation. However, it is not designed for forced aeration. Hence, this study aimed to develop a small-scale submerged shaking culture system enabling forced aeration into the medium. A forced aeration control system for multiple vessels allows shaking, suppresses volatilization, and is attachable externally to existing shaking tables. Using a specially developed plug, medium volatilization was reduced to less than 10%, even after 45 h of continuous aeration (~ 60 mL/min of dry air) in a 50 mL working volume. Escherichia coli IFO3301 cultivation with aeration was completed within a shorter period than that without aeration, with a 35% reduction in the time-to-reach maximum bacterial concentration (26.5 g-dry cell/L) and a 1.25-fold increase in maximum concentration. The maximum bacterial concentration achieved with aeration was identical to that obtained using the Erlenmeyer flask, with a 65% reduction in the time required to reach it. [ABSTRACT FROM AUTHOR]

In this research, the explosive wire method is used to prepare silver nanoparticles and study their effect on two types of bacteria, E. coli and Staphylococcus aureus. The X-ray diffraction pattern of silver nanoparticles after deposition on glass pieces shows a peak of silver and silver oxide. The FE-SEM morphology of silver oxide particles shows small spherical-like clusters of irregular flower-shaped particles. Meanwhile, the AFM analysis of the silver nanoparticles shows that the average roughness of the aggregates is 57 nm and the average size of the nanoparticles is 20.92 nm. The study of the effect of silver nanoparticles on two types of bacteria, namely E. coli and Staphylococcus aureus, has shown that these nanoparticles have achieved a killing rate of 99% for both types of bacteria. [ABSTRACT FROM AUTHOR]

For biomedical applications, hydroxyapatite and carbon nanotubes are currently being applied over duplex stainless steel (DSS) alone in order to increase corrosion resistance and biocompatibility. A composite of hydroxyapatite and multi-walled carbon nanotubes was used to improve biocompatibility, osseointegration, and corrosion resistance on 2205 DSS using electrophoretic deposition. The study investigates the effects of potential and time on the properties of the deposited layer in order to determine electrophoretic deposition factor values that are appropriate. The coating properties and effective groups of the phase resulting from this process are determined by Fourier transform infrared spectroscopy and X-ray diffraction. The antibacterial properties of E. coli bacterial strains are investigated for the coated layer. The adhesion between the hydroxyapatite and multi-walled carbon nanotube layers on the 2205 duplex stainless steel substrate was qualitatively evaluated using the adhesive tape test. It was found that the optimal suspension, which consists of 65 weight percent hydrogen acetate and 35 weight percent multi-walled carbon nanotubes, had a homogeneous morphology, a thick structure, and no cracks when coated at 50 V for two minutes. [ABSTRACT FROM AUTHOR]

We aimed to investigate the detection rate of causative organisms in stone-related pyelonephritis and to compare their distribution according to patient backgrounds. We retrospectively identified patients with stone-related pyelonephritis. Clinical data were collected between November 2012 and August 2020 at Wakayama Medical University Hospital, including on patient backgrounds and causative organisms. Patients were categorized by Eastern Cooperative Oncology Group performance status (PS) as the good PS group (0, 1) and the poor PS group (2–4). Bacteria were divided into Gram-positive cocci (GPC) or non-GPC groups and logistic regression analysis was used to examine factors that predict detection of GPC. Seventy-nine patients had stone-related pyelonephritis, 54 (68.4 %) in the good PS group and 25 (31.6 %) in the poor PS group. In the good PS group, Escherichia coli (67 %) was followed by Klebsiella species (9 %), while in the poor PS group, Escherichia coli (20 %) was followed by Enterococci and Staphylococci (12 %). GPC detection rate was significantly higher in the poor PS group than in the good PS group (40.0 % vs 14.8 %, p = 0.016), and multivariate logistic regression analysis showed that poor PS was an independent factor predicting detection of GPC (OR = 6.54, p = 0.02). The distribution of the causative organisms in stone pyelonephritis was similar to that in common complicated urinary tract infections. Poor PS may be an independent predictor of GPC detection in patients with stone pyelonephritis. [ABSTRACT FROM AUTHOR]

Shiga toxin-producing Escherichia coli (STEC) strains have emerged as important foodborne pathogens of global public health concern, causing life-threatening diseases. Animals and their products have been documented as important reservoirs for STECs, especially E. coli O157. The aim of this study was to investigate STECs from healthy and diarrhoeic sheep in Sanandaj, Iran. In the current study, a total of 81 sheep faecal samples were taken (22 from diarrhoeic sheep and 59 from healthy sheep). E. coli and subsequently STEC strains was detected according to standard protocol (cultural characterisation and PCR assays). Finally, the frequency of Shiga-toxin producing gene(s) (stx1, stx2), intimin (eaeA) and enterohaemolysin (hlyA) was detected among STEC isolates using duplex PCR. Totally, 42 E. coli were isolated from 81 faecal samples (51.85% contamination). Of these, 34 isolates (80.9%) were identified as STEC patotypes based on Sorbitol-MacConkey (SMAC) medium culturing and also the presence of stx1 and/or stx2. Of these, only 3 isolates (7.1%) were identified as serotype O157:H7 based on PCR assay. In addition, the results showed that STEC bacteria were significantly more prevalent in diarrhoeic samples than in healthy samples (50% vs. 22.1%). Overall, the PCR results showed that 33 (97%), 12 (35.3%) and 8 (23.5%) isolates carried stx1, stx2 and hlyA, respectively. The eaeA gene was not found in any isolate. The number of isolated STEC bacteria in spring (10 isolates) and winter (14 isolates) were significantly higher than those in summer (4 isolates) and autumn (6 isolates) (P=0.039). Also, the number of STEC in diarrhoea samples was significantly higher compared to non-diarrhoea samples (P=0.032). In conclusion, the present study revealed high prevalence rate of STEC including serotype O157:H7 and non-O157:H7 in sheep faeces which highlights the importance of sheep as a reservoir of STEC pathogen in Sanandaj region. Therefore, additional control and preventive measures must be undertaken to control the contamination by this pathogen. [ABSTRACT FROM AUTHOR]

The potential risk of bacteria‐induced prosthetic infection during implantation/post‐operative healing raises a serious concern about the success of implant/surgery. In this context, the present study successfully established the antibacterial efficacy of the electret form of Mg1‐xCaxSi1‐xZrxO3 (x = 0, 0.1, 0.2, 0.3, 0.4 [MCSZO‐X]) bioceramics, toward both, Escherichia Coli and Staphylococcus aureus bacteria with reference to those of hydroxyapatite (HAP). MCSZO‐X bioceramics were synthesized using a solid‐state route. The influence of Ca‐ and Zr co‐doping on the crystallite size of MCSZO‐X has been analyzed using X‐ray peak profile analyses. The electrets were developed by corona poling of sintered MCSZO‐X samples at voltage and temperature of 20 kV and 500°C (30 min), respectively. The charge, stored on the surface of MCSZO‐X electret samples was calculated to be 0.253, 0.294, 0.320, 0.173, and 0.161 µC/cm2 via thermally stimulated depolarized current measurement. The positive and negative ends of MCSZO‐ X electrets exhibited a reduction in the viability of E. coli bacteria by (24%, 25%, 30%, 43%, and 42%) and (29%, 37%, 39%, 51%, and 48%), respectively, in comparison to those of HAP. On the contrary, the viability of S. aureus bacteria has decreased by (26%, 33%, 35%, 46%, and 42%) and (21%, 22%, 27%, 395, and 37%) on the surfaces of the positive and negative ends of MCSZO‐ X electrets, respectively, with the reference of those of HAP. The mechanism of electret‐induced antibacterial activity has been revealed via various assays, such as catalase activity, superoxide production (SOD), , protein estimation, and lipid peroxidation (LPO) assays. The positive ends of MCSZO‐X electrets demonstrate antibacterial efficacy by means of more reactive oxygen species generation as compared to their negative ends of electrets and uncharged surfaces of MCSZO‐X samples, as revealed by SOD, protein estimation, catalase activity, and LPO assays. However, the negative ends of electrets prevent the adhesion of bacterial cells via electrostatic repulsion. [ABSTRACT FROM AUTHOR]

Pistacia lentiscus leaf extract has been used as a reducing and capping agent for the green production of zinc oxide nanoparticles (ZnO NPs) to evaluate their antioxidant and antibacterial properties. The optical and structural properties were determined by ultraviolet-visible (UV-Vis) spectra, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). In the UV-Vis spectra, an absorption peak at 310 nm was observed, whereas the FTIR spectra revealed a peak at 680 cm-1, attributed to the vibration of ZnO NPs and confirmed their formation. X-ray analysis showed the crystalline quality of the ZnO product, with well-defined peaks on the (002), (100), and (101) planes, confirming a hexagonal structure (JCPDS-file: 36-1451). The grain size of the ZnO NPs was approximately 33.90 nm in diameter. Using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (EDS), the morphology of the nanoparticles resembled dried cotton, whereas EDS confirmed the presence of zinc (Zn) and oxygen (O). The evaluation of antioxidant activity involved the DPPH test, thin-layer chromatography (TLC) bioautography, and spectrophotometric assay. The methanolic extract exhibited high antiradical potential, followed by aqueous, etheric, and finally ZnO NPs. Testing the antibacterial activity against two Gram-positive bacterial strains (Staphylococcus aureus and Bacillus cereus) and two Gram-negative strains (Escherichia coli and Pseudomonas aeruginosa) involved determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results showed that zinc oxide nanoparticles displayed considerable antibacterial effects compared with crude extracts, demonstrating inhibition zones of (24 ± 1) mm and (20 ± 2) mm, respectively, against E. coli and P. aeruginosa, with a bactericidal effect evident by a MBC/MIC ratio of 2. [ABSTRACT FROM AUTHOR]

[Display omitted] Outer membrane vesicle-functionalized nanoparticles (OMV-NPs) have attracted significant interest, especially regarding drug delivery applications and vaccines. Here, we report on novel OMV-NPs by applying bioorthogonal click reaction for encapsulating gold nanoparticles (NPs) within outer membrane vesicles (OMVs) by covalent coupling. For this purpose, outer membrane protein A (OmpA), abundant in large numbers (due to 100,000 copies/cell [1]) in OMVs, was modified via the incorporation of the unnatural amino acid p–azidophenylalanine. The azide group was covalently coupled to alkyne-functionalized NPs after incorporation into OmpA. A simplified procedure using low-speed centrifugation (1,000 x g) was developed for preparing OMV-NPs. The OMV-NPs were characterized by zeta potential, Laurdan-based lipid membrane dynamics studies, and the enzymatic activity of functionalized OMVs with surface-displayed nicotinamide adenine dinucleotide oxidase (Nox). In addition, OMVs from attenuated bacteria (ClearColiTM BL21(DE3), E. coli F470) with surface-displayed Nox or antibody fragments were prepared and successfully coupled to AuNPs. Finally, OMV-NPs displaying single-chain variable fragments from a monoclonal antibody directed against epidermal growth factor receptor were applied to demonstrate the feasibility of OMV-NPs for tumor cell targeting. [ABSTRACT FROM AUTHOR]

Group A rotavirus (RVA) is the primary etiological agent of acute gastroenteritis (AGE) in children under 5 years of age. Despite the global implementation of vaccines, rotavirus infections continue to cause over 120,000 deaths annually, with a majority occurring in developing nations. Among infants, the P[8] rotavirus strain is the most prevalent and can be categorized into four distinct lineages. In this investigation, we expressed five VP4(aa26-476) proteins from different P[8] lineages of human rotavirus in E. coli and assessed their immunogenicity in rabbits. Among the different P[8] strains, the Wa-VP4 protein, derived from the MT025868.1 strain of the P[8]-1 lineage, exhibited successful purification in a highly homogeneous form and significantly elicited higher levels of neutralizing antibodies (nAbs) against both homologous and heterologous rotaviruses compared to other VP4 proteins derived from different P[8] lineages in rabbits. Furthermore, we assessed the immunogenicity of the Wa-VP4 protein in mice, pigs, and cynomolgus monkeys, observing that it induced robust production of nAbs in all animals. Interestingly, there was no significant difference between in nAb titers against homologous and heterologous rotaviruses in pigs and mankeys. Collectively, these findings suggest that the Wa-VP4* protein may serve as a potential candidate for a rotavirus vaccine. [ABSTRACT FROM AUTHOR]

BACKGROUND: Natural bone morphogenetic protein 2 disperses and degrades rapidly in vivo, reducing local concentration and therapeutic efficacy. Simply combining bone morphogenetic protein 2 with tissue engineering scaffolds could not stay in vivo for a long time, making it difficult to achieve good sustained and controlled release effects. OBJECTIVE: To prepare and test the biological properties and chondrogenic induction effect of collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold. METHODS: SD rat tail collagen was extracted and a collagen cartilage scaffold was prepared using a vacuum freeze-drying machine chemical crosslinking method. The plasmid expressing collagen-binding domain-bone morphogenetic protein 2 was constructed by rapid cloning C112 homologous recombination, constructed by genetic engineering, and introduced into E. coli, and then collagen-binding domain-bone morphogenetic protein 2 was isolated and purified. Natural bone morphogenetic protein 2 and collagen-binding domain-bone morphogenetic protein 2 were combined with collagen cartilage scaffolds, respectively, to detect the release level of bone morphogenetic protein 2 in the scaffolds. The biocompatibility of collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold was detected by CCK-8 assay and F-Actin staining. Bone marrow mesenchymal stem cells were implanted on two kinds of collagen cartilage scaffolds for chondrogenic induction, and their chondrogenic induction activity was tested. RESULTS AND CONCLUSION: (1) The binding rate of collagen-binding domain-bone morphogenetic protein 2 to collagen cartilage scaffolds was higher than that of natural bone morphogenetic protein 2 (P < 0.05). After being immersed in PBS for 7 days in vitro, the release of bone morphogenetic protein 2 in the collagen-binding domain bone morphogenetic protein 2-collagen cartilage scaffold was smaller than that in the natural bone morphogenetic protein 2-collagen cartilage scaffold (P < 0.05). The results of the CCK-8 assay and F-Actin staining showed that the collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold had no obvious cytotoxicity and had good biocompatibility. (2) After 14 days of chondrogenic induction, ELISA detection demonstrated that the expressions of agglutincan and type II collagen A1 in the collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold group were higher than those in the natural bone morphogenetic protein 2-collagen cartilage scaffold group (P < 0.05). Under scanning electron microscopy, more bone marrow mesenchymal stem cells were observed on the inner wall of the pores of the two groups of scaffolds, and the cell morphology and size were the same, and the cells were closely arranged, without cell fragmentation or abnormal morphology. (3) The results indicate that the collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold has good biological properties and chondrogenic induction activity. [ABSTRACT FROM AUTHOR]

Background: Uterine dehiscence, an infrequent event often mistaken for uterine rupture, is rarely linked to post-cesarean section procedures and can result in severe complications, notably puerperal sepsis. In this report, we present a case that exemplifies the onset of puerperal sepsis and the emergence of intra-abdominal abscesses attributed to uterine dehiscence following a lower segment cesarean section (LSCS). Case Report: Our patient, a 28-year-old woman in her third pregnancy, underwent LSCS 1 week earlier. Subsequently, she returned to the hospital with lower abdominal pains, fever, and malodorous vaginal discharge. Computed tomography (CT) scan of whole abdomen verified uterine dehiscence and pus collection at the subhepatic region and right paracolic gutter. After referral to a specialized hospital, laboratory findings indicated an elevated white blood cell count and alkaline phosphatase levels, and coagulation abnormalities. She underwent an exploratory laparotomy, which unveiled uterine dehiscence, abscesses, and adhesions, necessitating a total abdominal hysterectomy and abdominal toileting. Pus culture analysis identified the presence of E. coli, which was susceptible to ampicillin/sulbactam. Complications were encountered after surgery, including wound dehiscence and pus re-accumulation. Successful management involved vacuum dressings and percutaneous drainage. Eventually, her condition improved and she was discharged, without additional complications. Conclusions: This report underscores the importance of considering cesarean scar dehiscence as a diagnosis in women with previous cesarean deliveries who present during subsequent pregnancies with symptoms such as abdominal pain or abdominal sepsis. Diagnostic tools, such as CT, play pivotal roles, and the timely performance of an exploratory laparotomy is paramount when suspicion arises. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the potential mechanisms associated with the persistence of chloramphenicol (CHP) resistance in Escherichia coli and Salmonella enterica isolated from pigs, pork, and humans in Thailand. The CHP-resistant E. coli (n = 106) and Salmonella (n = 57) isolates were tested for their CHP susceptibility in the presence and absence of phenylalanine arginine β-naphthylamide (PAβN). The potential co-selection of CHP resistance was investigated through conjugation experiments. Whole genome sequencing (WGS) was performed to analyze the E. coli (E329, E333, and E290) and Salmonella (SA448, SA461, and SA515) isolates with high CHP MIC (32–256 μg/mL) and predominant plasmid replicon types. The presence of PAβN significantly reduced the CHP MICs (≥4-fold) in most E. coli (67.9%) and Salmonella (64.9%). Ampicillin, tetracycline, and streptomycin co-selected for CHP-resistant Salmonella and E. coli-transconjugants carrying cmlA. IncF plasmids were mostly detected in cmlA carrying Salmonella (IncFIIAs) and E. coli (IncFIB and IncF) transconjugants. The WGS analysis revealed that class1 integrons with cmlA1 gene cassette flanked by IS26 and TnAs1 were located on IncX1 plasmid, IncFIA(HI1)/HI1B plasmids and IncFII/FIB plasmids. IncFIA(HI1)/HI1B/Q1in SA448 contained catA flanked by IS1B and TnAs3. In conclusion, cross resistance through proton motive force-dependent mechanisms and co-selection by other antimicrobial agents involved the persistence of CHP-resistance in E. coli in this collection. Dissemination of CHP-resistance genes was potentially facilitated by mobilization via mobile genetic elements. [ABSTRACT FROM AUTHOR]

Erosion poses a significant threat to oceanic beaches worldwide. To combat this threat, management agencies often utilize renourishment, which supplements eroded beaches with offsite sand. This process can alter the physical characteristics of the beach and can influence the presence and abundance of microbial communities. In this study, we examined how an oceanic beach renourishment project may have impacted the presence and abundance of Escherichia coli (E. coli), a common bacteria species, and sand grain size, a sediment characteristic that can influence bacterial persistence. Using an observational field approach, we quantified the presence and abundance of E. coli in sand (from sub-tidal, intertidal, and dune zones on the beach) and water samples at study sites in both renourished and non-renourished sections of Folly Beach, South Carolina, USA in 2014 and 2015. In addition, we also measured how renourishment may have impacted sand grain size by quantifying the relative frequency of grain sizes (from sub-tidal, intertidal, and dune zones on the beach) at both renourished and non-renourished sites. Using this approach, we found that E. coli was present in sand samples in all zones of the beach and at each of our study sites in both years of sampling but never in water samples. Additionally, we found that in comparison to non-renourished sections, renourished sites had significantly higher abundances of E. coli and coarser sand grains in the intertidal zone, which is where renourished sand is typically placed. However, these differences were only present in 2014 and were not detected when we resampled the study sites in 2015. Collectively, our findings show that E. coli can be commonly found in this sandy beach microbial community. In addition, our results suggest that renourishment has the potential to alter both the physical structure of the beach and the microbial community but that these impacts may be short-lived. [ABSTRACT FROM AUTHOR]

Wastewater discharge into the environment in resource-poor countries poses a threat to public health. Studies in this area within these countries are limited, and the use of high-throughput whole-genome sequencing technologies is lacking. Therefore, understanding of environmental impacts is inadequate. The present study investigated the antibiotic resistance profiles and diversity of beta-lactamases in Escherichia coli strains isolated from environmental water sources in Accra, Ghana. Microbiological analyses were conducted on wastewater samples from three hospitals, a sewage and wastewater treatment plant, and water samples from two urban surface water bodies. Confirmed isolates (N = 57) were selected for phenotypic antibiotic resistance profiles. Multi-drug-resistant isolates (n = 25) were genome sequenced using Illumina MiSeq sequencing technology and screened for sequence types, antibiotic resistance, virulence and beta-lactamase genes, and mobile genetic elements. Isolates were frequently resistant to ampicillin (63%), meropenem (47%), azithromycin (46%), and sulfamethoxazole-trimethoprim (42%). Twenty different sequence types (STs) were identified, including clinically relevant ones such as ST167 and ST21. Five isolates were assigned to novel STs: ST14531 (n = 2), ST14536, ST14537, and ST14538. The isolates belonged to phylogroups A (52%), B1 (44%), and B2 (4%) and carried β-lactamase (TEM-1B, TEM-1C, CTX-M-15, and blaDHA-1) and carbapenemase (OXA-1, OXA-181) resistance genes. Dominant plasmid replicons included Col440I (10.2%) and IncFIB (AP001918) (6.8%). Polluted urban environments in Accra are reservoirs for antibiotic-resistant bacteria, posing a substantial public health risk. The findings underscore the need for targeted public health interventions to mitigate the spread of antibiotic-resistant bacteria and protect public health. [ABSTRACT FROM AUTHOR]

Enterohemorrhagic E. coli (EHEC) is considered to be the most dangerous pathotype of E. coli, as it causes severe conditions such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). Antibiotic treatment of EHEC infections is generally not recommended since it may promote the production of the Shiga toxin (Stx) and lead to worsened symptoms. This study explores how exposure to the fluoroquinolone ciprofloxacin reorganizes the transcriptome and proteome of EHEC O157:H7 strain EDL933, with special emphasis on virulence-associated factors. As expected, exposure to ciprofloxacin caused an extensive upregulation of SOS-response- and Stx-phage proteins, including Stx. A range of other virulence-associated factors were also upregulated, including many genes encoded by the LEE-pathogenicity island, the enterohemolysin gene (ehxA), as well as several genes and proteins involved in LPS production. However, a large proportion of the genes and proteins (17 and 8%, respectively) whose expression was upregulated upon ciprofloxacin exposure (17 and 8%, respectively) are not functionally assigned. This indicates a knowledge gap in our understanding of mechanisms involved in EHECs response to antibiotic-induced stress. Altogether, the results contribute to better understanding of how exposure to ciprofloxacin influences the virulome of EHEC and generates a knowledge base for further studies on how EHEC responds to antibiotic-induced stress. A deeper understanding on how EHEC responds to antibiotics will facilitate development of novel and safer treatments for EHEC infections. [ABSTRACT FROM AUTHOR]

Adherent-invasive Escherichia coli (AIEC) pathobionts, which are characterized by their ability to adhere to and invade intestinal epithelial cells, are associated with the etiopathogenesis of inflammatory bowel diseases (IBDs). Outer membrane vesicles (OMVs) released by AIEC strains can facilitate the interaction of these bacteria with host cells through delivering bacterial effectors. The aim of this study was to determine the ability of OMVs derived from AIEC strain LF82 to induce the host immune response, leading to production of proinflammatory cytokines and also altering the gene expression of junction-associated proteins in the human epithelial colorectal adenocarcinoma Caco-2 cell line. OMVs were extracted from AIEC strain LF82, and the cell viability of Caco-2 cells treated with these vesicles was assessed by MTT assay. The morphology and size distribution of vesicles were analyzed using transmission electron microscopy and dynamic light scattering, respectively. Gene expression of occludin, ZO-1, claudin-2, E-cadherin, TLR-2, and TLR-4 in response to OMVs was assessed in Caco-2 cells by RT-qPCR. Moreover, the secretion of IL-8 and TNF-α into the supernatant of Caco-2 cells upon treatment with OMVs was measured using ELISA. Our results demonstrated that OMVs upregulated the gene expression level of TLRs and also altered the gene expression level of junction-associated proteins. OMVs derived from AIEC may play a major role in the promotion of intestinal inflammation and epithelial barrier dysfunction. However, further investigations are needed to elucidate the putative role of OMVs in the pathogenesis of AIEC and IBD. [ABSTRACT FROM AUTHOR]

In order to search for high specific activity and the resistant xylanases to XIP-I and provide more alternative xylanases for industrial production, a strain of Fusarium graminearum from Triticum aestivum grains infected with filamentous fungus produced xylanases was isolated and identified. Three xylanase genes from Fusarium graminearum Z-1 were cloned and successfully expressed in E. coli and P. pastoris, respectively. The specific activities of Fgxyn1,EFgxyn2 and EFgxyn3 for birchwood xylan were 38.79, 0.85 and 243.83 U/mg in E. coli, and 40.11, 0 and 910.37 U/mg in P. pastoris, respectively. EFgxyn3 and PFgxyn3 had the similar optimum pH at 6.0 and pH stability at 5.0–9.0. However, they had different optimum temperature and thermal stability, with 30 °C for EFgxyn3 and 40 °C for PFgxyn3, and 4–35 °C for EFgxyn3 and 4–40 °C for PFgxyn3, respectively. The substrate spectrum and the kinetic parameters showed that the two xylanases also exhibited the highest xylanase activity and catalytic efficiency (kcat/km) toward birchwood xylan, with 243.83 U/mg and 61.44 mL/mg/s for EFgxyn3 and 910.37 U/mg and 910.37 mL/mg/s for PFgxyn3, respectively. This study provided a novel mesophilic xylanase with high specific activity and catalytic efficiency, thus making it a promising candidate for extensive applications in animal feed and food industry. [ABSTRACT FROM AUTHOR]

Microbial cell factories serve as pivotal platforms for the production of high-value natural products, which tend to accumulate on the cell membrane due to their hydrophobic properties. However, the limited space of the cell membrane presents a bottleneck for the accumulation of these products. To enhance the production of intracellular natural products and alleviate the burden on the cell membrane caused by product accumulation, researchers have implemented various membrane engineering strategies. These strategies involve modifying the membrane components and structures of microbial cell factories to achieve efficient accumulation of target products. This review summarizes recent advances in the application of membrane engineering technologies in microbial cell factories, providing case studies involving Escherichia coli and yeast. Through these strategies, researchers have not only improved the tolerance of cells but also optimized intracellular storage space, significantly enhancing the production efficiency of natural products. This article aims to provide scientific evidence and references for further enhancing the efficiency of similar cell factories. [ABSTRACT FROM AUTHOR]

Background: Dihydroxyacetone (DHA) stands as a crucial chemical material extensively utilized in the cosmetics industry. DHA production through the dephosphorylation of dihydroxyacetone phosphate, an intermediate product of the glycolysis pathway in Escherichia coli, presents a prospective alternative for industrial production. However, insights into the pivotal enzyme, dihydroxyacetone phosphate dephosphorylase (HdpA), remain limited for informed engineering. Consequently, the development of an efficient tool for high-throughput screening of HdpA hypermutants becomes imperative. Results: This study introduces a methylglyoxal biosensor, based on the formaldehyde-responding regulator FrmR, for the selection of HdpA. Initial modifications involved the insertion of the FrmR binding site upstream of the −35 region and into the spacer region between the −10 and −35 regions of the constitutive promoter J23110. Although the hybrid promoter retained constitutive expression, expression of FrmR led to complete repression. The addition of 350 μM methylglyoxal promptly alleviated FrmR inhibition, enhancing promoter activity by more than 40-fold. The methylglyoxal biosensor system exhibited a gradual increase in fluorescence intensity with methylglyoxal concentrations ranging from 10 to 500 μM. Notably, the biosensor system responded to methylglyoxal spontaneously converted from added DHA, facilitating the separation of DHA producing and non-producing strains through flow cytometry sorting. Subsequently, the methylglyoxal biosensor was successfully applied to screen a library of HdpA mutants, identifying two strains harboring specific mutants 267G > T and D110G/G151C that showed improved DHA production by 68% and 114%, respectively. Expressing of these two HdpA mutants directly in a DHA-producing strain also increased DHA production from 1.45 to 1.92 and 2.29 g/L, respectively, demonstrating the enhanced enzyme properties of the HdpA mutants. Conclusions: The methylglyoxal biosensor offers a novel strategy for constructing genetically encoded biosensors and serves as a robust platform for indirectly determining DHA levels by responding to methylglyoxal. This property enables efficiently screening of HdpA hypermutants to enhance DHA production. [ABSTRACT FROM AUTHOR]

Aminopyrrolnitrin (APRN), a natural halogenated phenylpyrrole derivative (HPD), has strong antifungal and antiparasitic activities. Additionally, it showed 2.8-fold increased photostability compared to pyrrolnitrin, a commercially available HPD with antimicrobial activity. For microbial production of APRN, we first engineered anthranilate phosphoribosyltransferase encoded by trpD from Corynebacterium glutamicum, resulting in a TrpDA162D mutation that exhibits feedback-resistant against l-tryptophan and higher substrate affinity compared to wild-type TrpD. Plasmid-borne expression of trpDA162D in C. glutamicum TP851 strain with two copies of trpDA162D in the genome led to the production of 3.1 g/L l-tryptophan in flask culture. Subsequent step for l-tryptophan chlorination into 7-chloro-l-tryptophan was achieved by introducing diverse sources of genes encoding tryptophan 7-halogenase (PrnA or RebH) and flavin reductase (Fre, PrnF, or RebF). The combined expression of prnA from Serratia grimesii or Serratia plymuthica with flavin reductase gene from Escherichia coli, Pseudomonas fluorescens, or Lechevalieria aerocolonigenes yielded higher production of 7-chloro-l-tryptophan in comparison to other sets of two-component systems. In the next step, production of putative monodechloroaminopyrrolnitrin (MDAP) from 7-chloro-l-tryptophan was achieved through the expression of prnB encoding MDAP synthase from S. plymuthica or P. fluorescens. Finally, an artificial APRN biosynthetic pathway was constructed by simultaneously expressing genes coding for tryptophan 7-halogenase, flavin reductase, MDAP synthase, and MDAP halogenase (PrnC) from different microbial sources within the l-tryptophan-producing TP851 strain. As prnC from S. grimesii or S. plymuthica was introduced into the host strain, which carried plasmids expressing prnA from S. plymuthica, fre from E. coli, and prnB from S. plymuthica, APN3639 and APN3638 accumulated 29.5 mg/L and 28.1 mg/L of APRN in the culture broth. This study represents the first report on the fermentative APRN production by metabolically engineered C. glutamicum. [ABSTRACT FROM AUTHOR]

Background: The emergence of multidrug-resistant (MDR) Escherichia coli strains poses significant challenges in clinical settings, particularly when these strains harbor New Delhi metallo-ß-lactamase (NDM) gene, which confer resistance to carbapenems, a critical class of last-resort antibiotics. This study investigates the genetic characteristics and implications of a novel blaNDM-5-carrying plasmid pNDM-5-0083 isolated from an E. coli strain GZ04-0083 from clinical specimen in Zhongshan, China. Results: Phenotypic and genotypic evaluations confirmed that the E. coli ST167 strain GZ04-0083 is a multidrug-resistant organism, showing resistance to diverse classes of antibiotics including ß-lactams, carbapenems, fluoroquinolones, aminoglycosides, and sulfonamides, while maintaining susceptibility to monobactams. Investigations involving S1 pulsed-field gel electrophoresis, Southern blot analysis, and conjugation experiments, alongside genomic sequencing, confirmed the presence of the blaNDM-5 gene within a 146-kb IncFIB plasmid pNDM-5-0083. This evidence underscores a significant risk for the horizontal transfer of resistance genes among bacterial populations. Detailed annotations of genetic elements—such as resistance genes, transposons, and insertion sequences—and comparative BLAST analyses with other blaNDM-5-carrying plasmids, revealed a unique architectural configuration in the pNDM-5-0083. The MDR region of this plasmid shares a conserved gene arrangement (repA-IS15DIV-blaNDM-5-bleMBL-IS91-suI2-aadA2-dfrA12) with three previously reported plasmids, indicating a potential for dynamic genetic recombination and evolution within the MDR region. Additionally, the integration of virulence factors, including the iro and sit gene clusters and enolase, into its genetic architecture poses further therapeutic challenges by enhancing the strain's pathogenicity through improved host tissue colonization, immune evasion, and increased infection severity. Conclusions: The detailed identification and characterization of pNDM-5-0083 enhance our understanding of the mechanisms facilitating the spread of carbapenem resistance. This study illuminates the intricate interplay among various genetic elements within the novel blaNDM-5-carrying plasmid, which are crucial for the stability and mobility of resistance genes across bacterial populations. These insights highlight the urgent need for ongoing surveillance and the development of effective strategies to curb the proliferation of antibiotic resistance. [ABSTRACT FROM AUTHOR]

Recombinant multiepitope proteins (RMPs) are a promising alternative for application in diagnostic tests and, given their wide application in the most diverse diseases, this review article aims to survey the use of these antigens for diagnosis, as well as discuss the main points surrounding these antigens. RMPs usually consisting of linear, immunodominant, and phylogenetically conserved epitopes, has been applied in the experimental diagnosis of various human and animal diseases, such as leishmaniasis, brucellosis, cysticercosis, Chagas disease, hepatitis, leptospirosis, leprosy, filariasis, schistosomiasis, dengue, and COVID-19. The synthetic genes for these epitopes are joined to code a single RMP, either with spacers or fused, with different biochemical properties. The epitopes' high density within the RMPs contributes to a high degree of sensitivity and specificity. The RMPs can also sidestep the need for multiple peptide synthesis or multiple recombinant proteins, reducing costs and enhancing the standardization conditions for immunoassays. Methods such as bioinformatics and circular dichroism have been widely applied in the development of new RMPs, helping to guide their construction and better understand their structure. Several RMPs have been expressed, mainly using the Escherichia coli expression system, highlighting the importance of these cells in the biotechnological field. In fact, technological advances in this area, offering a wide range of different strains to be used, make these cells the most widely used expression platform. RMPs have been experimentally used to diagnose a broad range of illnesses in the laboratory, suggesting they could also be useful for accurate diagnoses commercially. On this point, the RMP method offers a tempting substitute for the production of promising antigens used to assemble commercial diagnostic kits. [ABSTRACT FROM AUTHOR]