Bacterial Growth Research Articles

Faecalibacterium prausnitzii A2-165 metabolizes host- and media-derived chemicals and induces transcriptional changes in colonic epithelium in GuMI human gut microphysiological system

Aim: Recently, a GuMI gut microphysiological system has been established to coculture oxygen-intolerant Faecalibacterium prausnitzii (F. prausnitzii ) A2-165 with organoids-derived primary human colonic epithelium. This study aims to test if this GuMI system applies to different donors with different healthy states and uses metabolomics to reveal the role of gut microbes in modulating host- and diet-derived molecules in the gut lumen. Methods: Organoids-derived colonic monolayers were generated from an uninflamed region of diverticulitis, ulcerative colitis, and Crohn’s disease patients and then integrated into the GuMI system to coculture with F. prausnitzii A2-165 for 2 to 4 days. Apical media was collected for metabolomic analysis. Targeted metabolomics was performed to profile 169 polar chemicals under three conditions: conventional static culture without bacteria, GuMI without bacteria, and GuMI with F. prausnitzii . The barrier function of monolayers was measured using transepithelial resistance. Results: GuMI successfully cocultured patient-derived monolayers and F. prausnitzii for up to 4 days, with active bacterial growth. Introducing flow and oxygen gradient significantly increases the barrier function, while exposure to F. prausnitzii slightly increases the barrier function. Targeted metabolomics screened 169 compounds and detected 76 metabolites, of which 70 significantly differed between at least two conditions. F. prausnitzii significantly modulates the levels of nucleosides, nucleobases, and amino acids on the apical side. Further analysis suggests that F. prausnitzii changes the mRNA level of 260 transcription factor genes in colonic epithelial cells. Conclusion: The GuMI physiomimetic system can maintain the coculture of F. prausnitzii and colonic epithelium from different donors. Together with metabolomics, we identified the modulation of F. prausnitzii in extracellular chemicals and colonic epithelial cell transcription in coculture with human colonic epithelium, which may reflect its function in gut lumen in vivo .

Potential of Nettle Infusion to Protect Common Bean from Halo Blight Disease

The use of plant-based preparations to replace chemical pesticides is a challenge for sustainable agriculture. Preparations from nettle (Urtica dioica L.) are good candidates, as the treatment of common bean plants (Phaseolus vulgaris L.) with aqueous suspensions of nettle reduced symptoms of halo blight disease caused by Pseudomonas syringae pv. phaseolicola (Pph). The aim of the present work was to test if nettle infusions (Ui) have similar effects and find out what activity is behind this: antimicrobial, promotion of the natural defenses of plants, and/or antioxidant. To achieve this, Pph growth was tested in the presence of infusions of nettle leaves collected in two different years (Ui18 and Ui22), and we found that it was only weakly inhibited at high concentrations of Ui18. Interestingly, Ui22 promoted bacteria growth at all concentrations. Second, we estimated the production of reactive oxygen species (ROS) in response to flagellin22 (flg22) in common bean leaf discs, since recognition of this bacterial peptide usually leads to ROS accumulation in tissues as a plant immune response. However, leaf discs that were preincubated in Ui showed no accumulation of ROS after flg22 treatment, suggesting that Ui can neutralize ROS production. Finally, in a Pph inoculation experiment of common bean plants grown in vitro, we observed that pretreatment of plants with Ui drastically reduced foliar oxidative damage and disease symptoms 6 h after inoculation. This effect was more noticeable for Ui22, which was related to the higher antioxidant activity found in this extract in comparison with Ui18. These results suggest that the protective properties of Ui are mainly due to the content of antioxidant bioactive compounds.

ε-Polylysine treatment maintains sensory quality, texture, flavor, and inhibits aerobic bacteria growth in vacuum-packed fresh-cut lettuce

Quality deterioration and aroma loss of vacuum-packed fresh-cut lettuce during storage are important factors affecting its commercial value. In this study, the effects of ε-polylysine (ε-PL) on the quality and flavor attributes of vacuum-packed fresh-cut lettuce were studied. Fresh-cut lettuce was treated with different concentrations of ε-PL (0.2, 0.8, and 1.5 g L−1), vacuum-packed and stored at 4 °C for 12 d. The results showed that ε-PL treatment maintained the color and texture of fresh-cut lettuce, and reduced chlorophyll degradation and ascorbic acid loss. In addition, ε-PL treatment inhibited the growth of aerobic bacteria, and maintained or increased some aroma components such as (E)-2-hexenal, n-hexanol, hexanal, limonene, benzaldehyde. These results indicate that ε-PL treatment has potential practical application value in the preservation of vacuum-packed fresh-cut lettuce.

On-demand release of silver from composite hydrogel by cold atmospheric plasma jet for wound infection control

Silver is an antimicrobial commonly used within wound care chiefly in advanced dressings or in a topical cream form, such as silver sulfadiazine (SSD). Although silver is effective at controlling the growth of many common wound bacteria, it can be cytotoxic and can build up in tissue, stalling the healing process. Here, we demonstrate the development of an on-demand release system for delivery of silver from a composite hydrogel comprising sodium polyacrylate particles dispersed in a cryo-crosslinked polyvinyl alcohol carrier gel. Application of cold atmospheric plasma (CAP) jet to the silver loaded hydrogel resulted in controlled release of silver. This release is thought to occur due to the formation of nitrous acids in the hydrogel by the CAP, resulting in protonation of carboxylate groups in the hydrogel and subsequent gel de-swelling due to the reduction in interchain charge repulsion. The location of silver within the sodium polyacrylate particles was probed using scanning electron microscopy and EDX imaging. The released silver inhibited the growth of Enterococcus faecalis, Pseudomonas aeruginosa, and Staphylococcus aureus and significantly reduced the viable cell count of the P. aeruginosa biofilm.

Impact of thermosonication treatment on passion fruit juice: ANN/GA optimization, predictive modelling for shelf life and quality changes during storage

Abstract Optimized sugar-added passion fruit juice (OPFJ) was obtained after optimization of thermosonication treatments of passion fruit juice using hybrid Artificial neural network/Genetic algorithm. The quality parameters and shelf life of OPFJ stored at various temperatures were assessed. Baranyi and Ratkowsky’s square-root models proved the prediction accuracy of the theoretical model concerning the microbial population during storage. The lag phase value decreased with increasing storage temperature. Temperature rise from 8 to 25 °C decreased the shelf life from 17 to 8 days for OPFJ and 3.5 to 1.5 days for untreated juice. The activation energy and increase in the reaction rate on increase in temperature by 10 °C (Q 10 value) were also evaluated. Thermosonication increased the phenolic and β-carotene contents and maintained the pH, titratable acidity, ascorbic acid content, and antioxidant activity during storage. Thermosonication enhanced the quality and shelf life of juice. Predictive modelling effectively predicted the shelf life.

Microencapsulation of Origanum heracleoticum L. and Thymus vulgaris L. essential oils – novel strategy to combat multi-resistant Acinetobacter baumannii

Within the global rise of antimicrobial resistance enhanced by the COVID-19 pandemic, where Acinetobacter baumannii has been distinguished as an emerging multi-resistant pathogen, essential oils, become the focus of novel therapeutic approaches. Hypothesizing that encapsulated Origanum heracleoticum L. and Thymus vulgaris L. essential oils could express multi-target approach against A. baumannii, this study aimed to develop microencapsulated systems with optimal technological qualities using 2-hydroxypropyl-β-cyclodextrin as a carrier, and to evaluate their pharmacological potential against A. baumannii, and their morphological and physicochemical characteristics, safety and stability profiles. The highest yield and encapsulation efficiency were obtained with 1:10 essential oil to carrier, and 1.5:10 carrier to water w/w ratios. The formation of inclusion complexes was confirmed by Fourier Transform Infrared Spectroscopy. Both microencapsulates achieved improved homogeneity, particle surface, and thermal stability compared with the pure carrier. Dominant bioactive compounds (carvacrol and p-cymene in O. heracleoticum essential oil, and thymol and p-cymene in T. vulgaris essential oil) remained the most abundant after encapsulation. While non-encapsulated essential oils revealed similar antimicrobial activity towards clinical A. baumannii isolates obtained from COVID-19 patients, encapsulated O. heracleoticum essential oil inhibited the bacterial growth at lower concentrations than T. vulgaris essential oil microencapsulate. All samples significantly reduced the formation of A. baumannii biofilm, for at least 53.90% towards the most infective isolate according to the Caenorhabditis elegans assay. Further, in silico molecular docking study revealed strong interaction pattern of carvacrol and thymol with the outer membrane protein A, which is the main factor for the A. baumannii biofilm formation. Cytotoxicity investigation on human lung A549 cells showed high survival rate in the presence of all tested concentrations, and the stability study revealed notable preservation of the bioactives’ content and pharmacological potential. Altogether, microencapsulated essential oils exhibited a multi-target approach towards A. baumannii, with satisfactory preserving capability during storage.

Current Knowledge about Gastric Microbiota with Special Emphasis on Helicobacter pylori-Related Gastric Conditions

The gastric milieu, because of its very low acidic pH, is very harsh for bacterial growth. The discovery of Helicobacter pylori (H.p.) has opened a new avenue for studies on the gastric microbiota, thus indicating that the stomach is not a sterile environment. Nowadays, new technologies of bacterial identification have demonstrated the existence of other microorganisms in the gastric habitat, which play an important role in health and disease. This bacterium possesses an arsenal of compounds which enable its survival but, at the same time, damage the gastric mucosa. Toxins, such as cytotoxin-associated gene A, vacuolar cytotoxin A, lipopolysaccharides, and adhesins, determine an inflammatory status of the gastric mucosa which may become chronic, ultimately leading to a gastric carcinoma. In the initial stage, H.p. persistence alters the gastric microbiota with a condition of dysbiosis, predisposing to inflammation. Probiotics and prebiotics exhibit beneficial effects on H.p. infection, and, among them, anti-inflammatory, antioxidant, and antibacterial activities are the major ones. Moreover, the association of probiotics with prebiotics (synbiotics) to conventional anti-H.p. therapy contributes to a more efficacious eradication of the bacterium. Also, polyphenols, largely present in the vegetal kingdom, have been demonstrated to alleviate H.p.-dependent pathologies, even including the inhibition of tumorigenesis. The gastric microbiota composition in health and disease is described. Then, cellular and molecular mechanisms of H.p.-mediated damage are clarified. Finally, the use of probiotics, prebiotics, and polyphenols in experimental models and in patients infected with H.p. is discussed.

Synthesis of Green Brucite [NixMg1−x(OH)2] by Incorporation of Nickel Ions in the Periclase Phase (MgO) Applied as Pigments

Magnesium oxide is typically white and can be colorized with transition metal insertion by doping. We present the preparation of a green-colored hydroxide by the exchange of Mg2+ on the crystalline lattice with Ni2+ in MgO, using three nickel salts. MgOst was prepared by the colloidal starch suspension method, using cassava starch. The oxides and hydroxides, before and after, were characterized by X-ray diffraction (XRD), and show that a phase change occurs: a transition from periclase (MgO) to brucite (Mg(OH)2) due to the incorporation of nickel ions from different salts (acetate, chloride, and nitrate), resulting in the solid solution [NixMg1−x(OH)2]. The FTIR spectrum corroborates the crystallographic structure identified through XRD patterns, confirming the formation of a crystal structure resembling brucite. The new samples present a green color, indicative of the incorporation of the Ni2+ ions. The antimicrobial activity of products resulting from the doping of magnesium oxide with nickel and the precursor MgOst was assessed through the minimum inhibitory concentration (MIC) test. The evaluation included three bacterial strains: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Salmonella gallinarum (ATCC 9184), and a yeast strain, Candida albicans (ATCC 10231). The obtained results were promising; the tested samples exhibited antimicrobial activity, with a MIC ranging from 0.312 to 0.625 μg.μL−1. The nickel compound, derived from the precursor chloride salt, demonstrated superior MIC activity. Notably, all tested samples displayed bactericidal activity against the S. aureus strain and exhibited a broad spectrum of inhibition, encompassing both Gram-positive and Gram-negative strains. Only the nickel compounds derived from precursors with acetate and nitrate anions demonstrated antimicrobial activity against C. albicans, exhibiting a fungistatic behavior. Based on the conducted studies, [NixMg1−x(OH)2] has emerged as a promising antimicrobial agent, suitable for applications requiring the delay or inhibition of bacterial growth.

Seasonal freeze‒thaw processes impact microbial communities of soil aggregates associated with soil pores on the Qinghai–Tibet Plateau

BackgroundSeasonal freeze‒thaw (FT) processes alter soil formation and cause changes in soil microbial communities, which regulate the decomposition of organic matter in alpine ecosystems. Soil aggregates are basic structural units and play a critical role in microbial habitation. However, the impact of seasonal FT processes on the distribution of microbial communities associated with soil pores in different aggregate fractions under climate change has been overlooked. In this study, we sampled soil aggregates from two typical alpine ecosystems (alpine meadow and alpine shrubland) during the seasonal FT processes (UFP: unstable freezing period, SFP: stable frozen period, UTP: unstable thawing period and STP: stable thawed period). The phospholipid fatty acid (PLFA) method was used to determine the biomass of living microbes in different aggregate fractions.ResultsThe microbial biomass of 0.25–2 mm and 0.053–0.25 mm aggregates did not change significantly during the seasonal FT process while the microbial biomass of > 2 mm aggregates presented a significant difference between the STP and UTP. Bacterial communities dominated the microbes in aggregates, accounting for over 80% of the total PLFAs. The microbial communities of soil aggregates in the surface layer were more sensitive to the seasonal FT process than those in other soil layers. In the thawing period, Gram positive bacteria (GP) was more dominant. In the freezing period, the ratio of Gram-positive to Gram-negative bacterial PLFAs (GP/GN) was low because the enrichment of plant litter facilitated the formation of organic matter. In the freezing process, pores of 30–80 μm (mesopores) favored the habitation of fungal and actinobacterial communities while total PLFAs and bacterial PLFAs were negatively correlated with mesopores in the thawing process.ConclusionsThe freezing process caused a greater variability in microbial biomass of different aggregate fractions. The thawing process increased the differences in microbial biomass among soil horizons. Mesopores of aggregates supported the habitation of actinobacterial and fungal communities while they were not conducive to bacterial growth. These findings provide a further comprehension of biodiversity and accurate estimation of global carbon cycle.

Synergistic Improvement of Antibacterial and Osteogenic Differentiation of Thermomechanically Processed Mg-Zr-Sr-Ce Alloy: Insights into the Role of Precipitate Evolution Supported by AIMD Simulation Study.

In the present study, we have discussed the influence of forging temperature (623 K (FT623), 723 K (FT723) and 823 K (FT823)) on microstructure and texture evolution and its implication on mechanical behavior, in vitro-in vivo biocorrosion, antibacterial response, and cytocompatibility of microalloyed Mg-Zr-Sr-Ce alloy. Phase analysis, SEM, and TEM characterization confirm the presence of Mg12Ce precipitate, and its stability was further validated by performing ab initio molecular dynamic simulation study. FT723 exhibits strengthened basal texture, higher fraction of second phases, and particle-stimulated nucleation-assisted DRX grains compared to other two specimens, resulting in superior strength with comparable ductility. FT723 also exhibits superior corrosion resistance mainly due to the strengthened basal texture and lower dislocation density. All the specimens exhibit excellent antibacterial behavior with Gram-negative E. coli, Gram-positive Staphylococcus aureus, and Pseudomonas aeruginosa bacteria. 100% reduction of bacterial growth is observed within 24 h of culture of the specimens. Cytocompatibility was determined by challenging specimen extracts with the MC3T3-E1 cell lines. FT723 specimen exhibits the highest cell proliferation and alkaline phosphatase activity (ALP) because of its superior corrosion resistance. The ability of the specimens to be used in orthopedic implant application was evaluated by in vivo study in rabbit femur. Neither tissue-related infection nor the detrimental effect surrounding the implant was confirmed from histological analysis. Significant higher bone regeneration surrounding the FT723 specimen was observed in SEM analysis and fluorochrome labeling. After 60 days, the FT723 specimen exhibits the highest bone formation, suggesting it is a suitable candidate for orthopedic implant application.

Sulfated Chitosan-Modified CuS Nanocluster: A Versatile Nanoformulation for Simultaneous Antibacterial and Bone Regenerative Therapy in Periodontitis.

Periodontitis, a prevalent chronic inflammatory disease worldwide, is triggered by periodontopathogenic bacteria, resulting in the progressive destruction of periodontal tissue, particularly the alveolar bone. To effectively address periodontitis, this study proposed a nanoformulation known as CuS@MSN-SCS. This formulation involves coating citrate-grafted copper sulfide (CuS) nanoparticles with mesoporous silica (MSNs), followed by surface modification using amino groups and sulfated chitosan (SCS) through electrostatic interactions. The objective of this formulation is to achieve efficient bacteria removal by inducing ROS signaling pathways mediated by Cu2+ ions. Additionally, it aims to promote alveolar bone regeneration through Cu2+-induced pro-angiogenesis and SCS-mediated bone regeneration. As anticipated, by regulating the surface charges, the negatively charged CuS nanoparticles capped with sodium citrate were successfully coated with MSNs, and the subsequent introduction of amine groups using (3-aminopropyl)triethoxysilane was followed by the incorporation of SCS through electrostatic interactions, resulting in the formation of CuS@MSN-SCS. The developed nanoformulation was verified to not only significantly exacerbate the oxidative stress of Fusobacterium nucleatum, thereby suppressing bacteria growth and biofilm formation in vitro, but also effectively alleviate the inflammatory response and promote alveolar bone regeneration without evident biotoxicity in an in vivo rat periodontitis model. These findings contribute to the therapeutic effect on periodontitis. Overall, this study successfully developed a nanoformulation for combating bacteria and facilitating alveolar bone regeneration, demonstrating the promising potential for clinical treatment of periodontitis.

CORTICOSTEROID-INDUCED EXPRESSION OF MICROBIAL VIRULENCE CAN ENHANCE THE DEVELOPMENT OF HOST INFECTIOUS DISEASE

Corticosteroids regulate a number of physiological processes and are synthetic analogs of the natural steroid hormones produced by the adrenal cortex. As drugs, corticosteroids are non-inflammatory and are used for the treatment of plethora of conditions which include arthritis, kidney, skin, lungs or thyroid disorders, for the treatment and relief of symptoms of allergies and symptoms of some gastrointestinal disorders. In addition, glucocorticoids can regulate the effects of inflammatory disorders, including sepsis, autoimmune diseases, and allergies. These conditions are potentially fatal. Consequently, this drug class is among the most commonly prescribed globally. One representative of corticosteroid class of drugs is dexamethasone which is used to treat allergies, adrenal problems, arthritis, asthma, diseases of blood or bone marrow, inflammation, kidney diseases, different types of skin conditions, and episodes of multiple sclerosis. Virulence factors help bacteria colonize the host at the level of the cell. In their nature, these factors are secretory, associated with the membrane or present in the cytosol. Secretory factors allow bacterium to circumvent the host immune response, while membrane factors aid bacterium in adhesion to the host cell. Finally, cytosol factors help bacteria adapt metabolically, physiologically, and morphologically to their changing environment. One such factor is aspartyl proteinase, a protein that degrades other proteins and is a virulence factor in many pathogens playing a role in the host invasion process. Another important virulence factor is the ability to form biofilms, which can render bacteria resistant to antimicrobials. Despite the widespread use of corticosteroids, including dexamethasone, little is known about their possible influence on the expression of virulence factors such as aspartyl proteinase. If such a connection is to exist the use of corticosteroids could elicit pathogenesis in certain microbes. In the here-presented study we wanted to investigate the effects of dexamethasone on the growth, expression of aspartyl proteinase and biofilm formation in three E. coli strains that were previously isolated from patients suffering from urinary tract infection. To this aim, we amended the growth media with 0.5 mg/mL dexamethasone. Bacterial growth was measured over the period of 24 hours and the effect of dexamethasone was established at different time points. Administration of 0.5 mg/mL glucocorticoid drug dexamethasone did not significantly affect bacterial growth. However, it resulted in an increase in concentration of secreted E. coli virulence factor aspartyl proteinase, which increased up to 2.6-fold for some E. coli strains. In addition, we noted the increased biofilm formation in to three out of four studied strains. This study indicates dexamethasone as a possible trigger molecule for the expression of virulence factor aspartyl proteinase in E. coli.

Antimicrobial Properties of Flavonoid Derivatives with Bromine, Chlorine, and Nitro Group Obtained by Chemical Synthesis and Biotransformation Studies.

The search for new substances of natural origin, such as flavonoids, is necessary in the fight against the growing number of diseases and bacterial resistance to antibiotics. In our research, we wanted to check the influence of flavonoids with chlorine or bromine atoms and a nitro group on pathogenic and probiotic bacteria. We synthesized flavonoids using Claisen-Schmidt condensation and its modifications, and through biotransformation via entomopathogenic filamentous fungi, we obtained their glycoside derivatives. Biotransformation yielded two new flavonoid glycosides: 8-amino-6-chloroflavone 4'-O-β-D-(4″-O-methyl)-glucopyranoside and 6-bromo-8-nitroflavone 4'-O-β-D-(4″-O-methyl)-glucopyranoside. Subsequently, we checked the antimicrobial properties of the aforementioned aglycon flavonoid compounds against pathogenic and probiotic bacteria and yeast. Our studies revealed that flavones have superior inhibitory effects compared to chalcones and flavanones. Notably, 6-chloro-8-nitroflavone showed potent inhibitory activity against pathogenic bacteria. Conversely, flavanones 6-chloro-8-nitroflavanone and 6-bromo-8-nitroflavanone stimulated the growth of probiotic bacteria (Lactobacillus acidophilus and Pediococcus pentosaceus). Our research has shown that the presence of chlorine, bromine, and nitro groups has a significant effect on their antimicrobial properties.

Peptides with Antimicrobial Activity in the Saliva of the Malaria Vector Anopheles coluzzii.

Mosquito saliva plays a crucial physiological role in both sugar and blood feeding by helping sugar digestion and exerting antihemostatic functions. During meal acquisition, mosquitoes are exposed to the internalization of external microbes. Since mosquitoes reingest significant amounts of saliva during feeding, we hypothesized that salivary antimicrobial components may participate in the protection of mouthparts, the crop, and the gut by inhibiting bacterial growth. To identify novel potential antimicrobials from mosquito saliva, we selected 11 candidates from Anopheles coluzzii salivary transcriptomic datasets and obtained them either using a cell-free transcription/translation expression system or, when feasible, via chemical synthesis. Hyp6.2 and hyp13, which were predicted to be produced as propeptides and cleaved in shorter mature forms, showed the most interesting results in bacterial growth inhibition assays. Hyp6.2 (putative mature form, 35 amino acid residues) significantly inhibited the growth of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Serratia marcescens) bacteria. Hyp13 (short form, 19 amino acid residues) dose-dependently inhibited E. coli and S. marcescens growth, inducing membrane disruption in both Gram-positive and Gram-negative bacteria as indicated with scanning electron microscopy. In conclusion, we identified two A. coluzzii salivary peptides inhibiting Gram-positive and Gram-negative bacteria growth and possibly contributing to the protection of mosquito mouthparts and digestive tracts from microbial infection during and/or after feeding.

Antibacterial and Antibiofilm Potential of Ethanolic Extracts of Duguetia vallicola (Annonaceae) against in-Hospital Isolates of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic pathogen that is especially dominant in people with cystic fibrosis; the drug resistance expressed by this pathogen and its capacity for adaptation poses a significant challenge to its treatment and control, thereby increasing morbidity and mortality rates globally. In this sense, the search for new treatment alternatives is imminent today, with products of plant origin being an excellent alternative for use. The objective of this research was to evaluate the antibacterial and antibiofilm potential and to explore the possible effect of ethanolic extracts from the wood and bark of Duguetia vallicola on the cell membrane. Microdilution assays showed the inhibition of bacterial growth by more than 50%, with the lowest concentration (62.5 μg/mL) of both extracts evaluated. Furthermore, we report the ability of both extracts to inhibit mature biofilms, with inhibition percentages between 48.4% and 93.7%. Intracellular material leakage experiments (260/280 nm), extracellular pH measurements, and fluorescence microscopy with acridine orange (AO) and ethidium bromide (EB) showed cell membrane damage. This indicates that the antibacterial action of ethanolic extracts of D. vallicola is associated with damage to the integrity of the cell membrane and consequent death of these pathogens. These results serve as a reference for future studies in establishing the mechanisms of action of these extracts.

Does Nesting Material Affect Wood Duck (Aix sponsa) Nest Box Selection, Reproduction, and Eggshell Bacteria?

Wood Ducks (Aix sponsa) are secondary cavity nesters that use natural cavities and artificial nest boxes, the latter of which has been attributed to the recovery of populations across the southeastern US. Continual use of these boxes results in a buildup of bacteria, parasites, and other pathogens. To avoid the accumulation of these deleterious organisms, best management practices include the occasional removal of old nesting material (i.e., wood shavings) and replacement with fresh wood shavings. No studies have been performed on the effects of shaving material on nest box selection, nest success, and bacterial growth. We monitored 142 and 111 nest boxes in Florida and Georgia, USA, respectively, and filled a random sample with aspen or cedar shavings. We then swabbed the surface of 144 and 150 eggs during 2020 and 2021, respectively, to screen for culturable bacteria. We detected no effect of shaving type on nest box selection, nest success, or egg surface bacterial growth. We found 3-8 bacterial colony types (1-123 colony-forming units [CFU]/box) and 1-8 bacterial colony types (3-382 CFU/box) among the Georgia and Florida samples, respectively. We detected no effect from shaving type on Wood Duck reproduction or bacterial growth in the sampled nest boxes. We concluded that both shaving types are suitable nesting materials for box-nesting Wood Duck populations and the continued use of either would be a reasonable decision for managers.

Use of Lactoperoxidase Inhibitory Effects to Extend the Shelf Life of Meat and Meat Products.

Lactoperoxidase (LP) is an important enzyme of the salivary and mammary glands. It has been proven to increase the shelf life of raw milk by inhibiting the growth of bacteria, especially Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Pseudomonas spp. The aim of this work was to verify the use of LP to extend the shelf life of meat products. In vitro experiments showed inhibitory effects on the selected bacteria (Listeria innocua (ATCC 33090), Staphylococcus saprophyticus (CP054440.1), and Pseudomonas fluorescens (ATCC 13525) due to a prolongation of the lag phase of growth curves. A lower increase in viable counts (p < 0.05) was also found by testing pork cubes' surface treated with LP solution (5%) + L. innocua and stored for 7 days at 15 °C. LP has also been studied at concentrations of 0.25 and 0.50% in meat products (pork ham and pâté) during refrigerated storage (4 °C for 28 days). Lower viable counts were observed throughout the storage experiment, especially for 0.50% LP (p < 0.05). Meat products containing LP also showed lower levels of oxidation (MAD) (p < 0.05). According to these results, LP could extend the shelf life of a wider range of products.

Innovative coating of cotton textile fabrics for integrating outstanding flame hazard safety, UV protection, tensile strength strengthening and antibacterial properties

A rational green synthesis method was developed to produce sustainable nanocoatings for cotton fabrics that are flame retardant, strengthened, antibacterial, and UV protective. The nanocoatings were created using silica nanoparticles with an average size of 73.2 nm derived from rice husk (RH-SNP). These nanoparticles were adorned with ZnONPs with an average size of 7.6 nm, which were reduced and capped with molokhia extract made from molokhia stems by-products. The ultimate nanocomposite was evenly distributed in a chitosan solution using ultrasonication. The mass ratio of RH-SNP in the nanocoating was adjusted and fine-tuned for optimization. The coated cotton fabrics were analyzed using spectroscopic and microscopic techniques. The flammability of cotton fabrics treated with sustainable coatings was assessed. The coated fabrics exhibited significantly greater flame retardancy, achieving a zero burning rate compared to 110 mm/min for the untreated one. The enhanced flame-retardant properties were a result of the combined flame-retardant effects of RH-SNP and molokhia stem extract, along with decorated ZnONPs, which created a more robust protective char layer. The coated cotton's antibacterial characteristics showed significant inhibition of bacterial growth, resulting in a 10 mm distinct inhibition zone, while pure cotton had no inhibition zone. Additionally, the coated cotton fabrics had exceptional UV shielding properties with a UPF rating of 167.8, which was more than fourth the value of the uncoated fabric. The tensile strength and elongation of the cotton fabrics were enhanced after applying a sustainable nanocoating, indicating a beneficial effect on tensile strength. Furthermore, the coated fabrics exhibited exceptional durability characteristics.

The vaginal microbiota of healthy female cats

The vaginal microbiota of the queen (i.e., female cat) has never been described using culture independent methods. The objectives of the present research were to describe the vaginal microbiota of healthy domestic shorthair queens using both 16S rRNA sequencing and culture, and to assess the effects of age, living environment, and reproductive season on its composition. Thirty queens undergoing elective ovariectomy were included in the study. The vaginal samples were collected just before surgery, from animals under general anaesthesia. Two consecutive mini-swabs were introduced in the queens' vaginal tract. A preliminary study with 10 healthy queens aimed to negate sampling order's effect. Two consecutive samples for sequencing (5 queens, 10 swabs) and culture (5 queens, 10 swabs) were collected, confirming a match (100 % in culture, Bray-Curtis P = 0.96 in sequencing). The experiment included 20 queens that were prospectively grouped based on age (prepubertal N = 10, adult N = 10), living environment (indoor N = 10, outdoor N = 10), and time of the year, whether during the reproductive season (N = 10) or during seasonal anoestrous (N = 10). Bacteria were identified through metataxonomic analysis, amplifying the V1–V2 regions of 16S rRNA gene, and through standard culture followed by MALDI-TOF MS.The feline vaginal microbiota is dominated by Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria. Escherichia-Shigella, Streptococcus, and Pasteurella were the most abundant genera. Although culture underestimated bacterial richness and diversity compared to sequencing, Escherichia and Streptococcus were the most isolated bacteria. No bacterial growth was observed in 15 % of samples (N = 3/20), whereas growth of one or two bacterial species was observed in 64.7 % (N = 11/17) and 35.3 % (N = 6/17) of cases, respectively. No differences in terms of alpha (Kruskal-Wallis rank sum test P = 0.65) and beta diversity (Bray-Curtis, Unweighted and Weighted UniFrac analyses P > 0.5) were observed. Although a difference in alpha diversity based on phylogenetic tree (P = 0.02) was detected between indoor and outdoor queens. In conclusion, mixed and monoculture of Escherichia coli, Streptococcus canis, Staphylococcus felis, and Enterococcus spp. are normal findings within the cat vagina. Age and reproductive season do not influence the feline vaginal microbiota, whereas further research is needed to elucidate the role of the living environment.

Phosphorylation-amplified synchronized droplet microfluidics sensitizes bacterial growth kinetic real-time monitoring

The necessity for rapid and accurate bacterial growth monitoring is imperative across various domains, including healthcare and environmental safety. We introduce the self-synchronized droplet-amplified electrical screening cytometry (SYNC) system, a novel meld of droplet microfluidics and electrochemical amplification tailored for precise bacterial growth kinetic monitoring. SYNC encapsulates single bacteria in picolitre droplets, enabling real-time, fluorescence-free electrochemical monitoring. A specially devised phosphorylation-amplified culture medium translates bacterial metabolic activity into discernible electrical impedance changes. The dual-channel design and a rail-based structure in SYNC facilitate parallel screening and self-synchronization of droplets, addressing the limitations of conventional impedance cytometry. SYNC showcases a 5-fold enhancement in detection sensitivity and reduces 50% of the detection time compared to traditional approaches. Notably, SYNC is pioneering in providing exact initial bacterial concentrations, achieve to 104 bacteria/ml, a capability unmatched by existing real-time techniques measuring electrochemical variations. Along with its robust performance, this earmarks SYNC as a powerful tool for applications such as antibiotic susceptibility testing, food quality monitoring, and real-time water bacteria monitoring, paving the way for enhanced microbial process management and infection control.