Enriched Medium Research Articles

Validation of the Level 2 Modification for the Neogen® Molecular Detection Assay 2 - Salmonella Enteritidis/Salmonella Typhimurium Method for Detection of the Monophasic Variant Salmonella enterica 1,4,[5],12:-:1,2

Abstract Background The Neogen® Molecular Detection Assay 2—Salmonella Enteritidis/Salmonella Typhimurium (MDA2-SE/ST) method, Performance Tested Method SM (PTM) 122302, is a nucleic acid amplification test for specific detection of Salmonella enterica ser. Enteritidis (SE) and Salmonella enterica ser. Typhimurium (ST), including the ST monophasic variant Salmonella enterica 1,4,[5],12:i:-, in select poultry samples. Results for SE and ST are generated separately. Objective The objective of the study was to validate the MDA2-SE/ST method for detection of an additional monophasic variant of ST, S. enterica 1,4,[5],12:-:1,2. Methods A single strain of S. enterica 1,4,[5],12:-:1,2 was tested as part of a seven-strain inclusivity/exclusivity test panel. Strains were tested after growth in two enrichment media used in the method, buffered peptone water (BPW) and buffered peptone water—ISO formulation (BPW-ISO), and at two incubation temperatures, 35 ± 2 °C and 41.5 ± 1 °C. Results S. enterica 1,4,[5],12:-:1,2 produced positive results in the ST assay and negative results in the SE assay in both enrichment media and at both incubation temperatures. Results for the other six test strains were as expected under all conditions. Conclusions The MDA2-SE/ST method can detect the monophasic variant S. enterica 1,4,[5],12:-:1,2 as well as S. enterica ser. Typhimurium and the monophasic variant S. enterica 1,4,[5],12:i:-. The MDA2-SE/ST method maintains inclusiveness for S. enterica ser. Typhimurium despite flagellar antigen variation. Highlights The data were reviewed by the AOAC PTM Program and approval was granted for modification of the MDA2-SE/ST method, PTM 122302.

Osaka Feedback Model. III. Cosmological Simulation CROCODILE

We introduce our new cosmological simulation data set CROCODILE, executed using the GADGET4-Osaka smoothed particle hydrodynamics code. This simulation incorporates an updated supernova (SN) feedback model of Y. Oku et al. and an active galactic nuclei (AGN) feedback model. A key innovation in our SN feedback model is the integration of a metallicity- and redshift-dependent, top-heavy initial mass function. Our SN model introduces a new consideration that results in an order of magnitude difference in the energy injection rate per unit stellar mass formed at high redshift. The CROCODILE data set is comprehensive, encompassing a variety of runs with diverse feedback parameters. This allows for an in-depth exploration of the relative impacts of different feedback processes in galactic evolution. Our initial comparisons with observational data, spanning the galaxy stellar mass function, the star formation main sequence, and the mass–metallicity relation, show promising agreement, especially for the Fiducial run. These results establish a solid foundation for our future work. We find that SN feedback is a key driver in the chemical enrichment of the intergalactic medium (IGM). Additionally, the AGN feedback creates metal-rich, bipolar outflows that extend and enrich the circumgalactic medium and IGM over a few Mpc scales.

A polymerase chain reaction (PCR) method to detect emerging multidrug-resistant Salmonella Infantis harbouring pESI plasmid in seafood.

Salmonella Infantis is an emerging multidrug-resistant pathogen worldwide due to the acquisition of a megaplasmid pESI (Plasmid of Emerging Salmonella Infantis). Reported initially from poultry, the distribution of pESI-harbouring S. Infantis in other food types, including seafood, is unknown. This study aimed to develop and optimize a PCR assay for detecting pESI plasmid in Salmonella and non-Salmonella Enterobacterales. A duplex PCR targeting the hilA gene and a pESI-associated gene of S. Infantis was designed, and the PCR conditions were optimized. The specificity and sensitivity of the assay were established using 119 Salmonella serovars and 51 non-Salmonella bacterial strains. All Salmonella isolates yielded hilA PCR product, while only pESI S. Infantis was positive for both hilA and pESI genes. No amplification product was obtained with the DNA of 51 non-Salmonella bacterial strains. The detection limit of the duplex PCR was 104 CFU/ml of pure culture of pESI S. Infantis. The sensitivity of detection in artificially spiked shrimp meat was 1 CFU/g after 6 h of enrichment in lactose broth, followed by 12 h of selective enrichment in the Rappaport-Vassiliadis medium. The duplex assay will help screen seafood for Salmonella in general and pESI S. Infantis in particular. Given its high sensitivity, the PCR will be a valuable tool for seafood quality assurance. This approach decreases the typical 3-6 days' identification time of Salmonella to less than 24 hours. S. Infantis carrying the highly transmissible megaplasmid (pESI) is a significant food safety concern. Given its rapid geographical spread and high antimicrobial resistant traits, it is necessary to have a molecular tool that detects pESI-harbouring Salmonella. This study successfully developed a duplex PCR assay that simultaneously detects Salmonella enterica and pESI S. Infantis. This molecular tool will help understand the distribution, sources, and spread of MDR plasmid in the food environment.

The acceptability of implementation of group B Streptococcus testing: Perspectives from women and health professionals in the GBS3 trial: A qualitative study

ObjectiveTo determine the acceptability of different methods of routine testing for group B Streptococcus (GBS) colonisation to pregnant women and health care professionals (HCPs), and to examine barriers and facilitators to their implementation. DesignQualitative study, embedded in a cluster randomised trial SettingFour NHS maternity units participating in the GBS3 Trial: two conducting routine antenatal enriched culture medium (ECM) testing; and two using routine rapid intrapartum testing.Sample39 women and 25 HCPs purposively sampled to ensure representation of women with various birthing experiences and different professions.MethodsWomen were interviewed approximately 12 weeks postpartum by telephone or online video call, using a semi-structured topic guide. HCPs were interviewed during the testing period of the trial. Interviews were transcribed for thematic analysis and summarised using the framework method. ResultsFour categories of interest emerged: (1) views of routine testing; (2) acceptability of the testing procedure; (3) preferences on the types of test; (4) improving the testing procedure. Routine GBS testing was well received by both women and HCPs. Most participants found the procedure acceptable and were willing to receive the offer of testing in the future. Preferences for different testing methods varied, with participants emphasising the importance of evidence and informed choice. ConclusionsRoutine GBS testing is acceptable to most women and HCPs. Areas for consideration and the practicalities of implementing testing in maternity services are highlighted.

Leveraging Social Media for Enrichment in Buddhist Tourism: A Mixed-Methods Study between Pakistan and China

This research work takes a strategic perspective on how social media can be leveraged for use between Pakistan and China, considering cultural and historical ties under the roof of Buddhist tourism. The Uses and Gratification Theory (UGT) is applied in this qualitative study, complemented by the quantitative analysis of engagement through social media, to gain insights into why people visit different websites and how effective social media is in promoting tourism. The paper considered WeChat, Weibo, Instagram, and Facebook as they all have something unique to give to a tourist. The research has found that culturally relevant and visually rich content is much more effective in attracting Chinese tourists to the Buddhist heritage sites of Taxila and Takht- i-Bahi in Pakistan. Different online platforms have different preferences in presenting information and visual engagement, so WeChat is ideal for the dissemination of information and Instagram for visual engagement. Findings highlight the importance of cross-platform strategies and localized content for maximum outreach of tourism. Tables have been provided to compare the engagement metrics across the platforms, indicating which content types work well. This research provides actionable suggestions for tourism boards and marketers to develop targeted social media policies that can support higher tourist visits between countries and strengthen cultural bonds.

Molecular diagnosis of E.coliO157:H7 Which Isolated from Children with Diarrhea by using Multiplex PCR

A total of 96 stool samples were collected from children with bloody diarrhea from two hospitals in Baghdad. All samples were surveyed and examined for the presence of the Escherichia coli O157:H7 and differentiate it from other Non -Sorbitol Fermenting Escherichia coli (NSF E. coli). The Bacterial isolates were identifed by using morphological diagnostic methods, Samples were cultured on liquid enrichment medium, incubated at 37C? for 24 hrs, and then cultured on Cefixime Tellurite -Sorbitol MacConkey Agar (CT- SMAC). 32 non-sorbitol fermenting bacterial isolates were obtained of which 11 were identified as Escherichia coli by using traditional biochemical tests and API20E diagnostic system without differentiation between serotype O157:H7 and other NSF E. coli isolates . Four special biochemical tests were done for serotype O157:H7 differentiation from other NSF bacteria. Only 3 isolates belonging to the serotype O157:H7 were obtained . Latex agglutination test for O157 and H7 showed that the 3 isolates gave positive results with both tests. The Bacterial isolates were identifed by using Multiplex Polymerase Chain Reaction (MPCR) technology for the presence or absence of 4 genes (Stx1, Stx2, hlyA and eaeA) that encode for main virulence factors to diagnose E. coli O157:H7 isolated By using specific primers in MPCR . The result showed that one E. coli O157:H7 isolates contain all 4 genes , other isolates contain 3 genes: Stx2, hlyA & eaeA.

Cross-sectional study of antibiotic resistance to Escherichia coli and Salmonella spp. in cats in Yogyakarta, Indonesia, and Dili, Timor-Leste

Background and Aim: Antibiotics are used in veterinary clinics and animal hospitals to treat infectious diseases. However, the improper use of antibiotics causes antibiotic resistance, which threatens future disease therapeutics in pet animals. This study aimed to estimate the prevalence of Escherichia coli and Salmonella spp. in cats and their resistance to antibiotics in Yogyakarta Province, Indonesia (IDN), and Dili, Timor-Leste (TL). Materials and Methods: A total of 255 cat’s rectal swab samples from veterinary clinics and hospitals in Yogyakarta Province, IDN, and Dili, TL were collected. All samples were transferred aseptically into an enrichment medium and subjected to various culture tests for E. coli and Salmonella spp. identification. All identified isolates were tested for antibiotic sensitivity using Kirby−Bauer disk diffusion method. Results: This study successfully isolated E. coli from 172/255 (67.45%) rectal swab samples, that is, 122/188 samples (64.89%) from Yogyakarta Province, IDN, and 50/67 samples (74.6%) from Dili, TL. Salmonella spp. was isolated from 13/188 samples (6.91%) from Yogyakarta, IDN. The antibiotic susceptibility test indicated that more than 30% of E. coli were resistant to ampicillin (AMP) (IDN = 39.3%, TL = 50%) and tetracycline (TE) (IDN = 41.8%, TL = 42%), and more than 40% of Salmonella spp. were resistant to enrofloxacin (44%), TE (56%), streptomycin (61%), and AMP (83%). Conclusion: E. coli and Salmonella spp. succeeded isolation in cats from IDN and TL, and some isolates were resistant to antibiotics. Cats with diarrhea or digestive problems have a 9.5-fold increased risk of infection by Salmonella spp. Considering the prevalence of resistance to E. coli and Salmonella spp., it is important to manage antibiotic resistance distribution across companion animals and humans because both species share the same living environment. Keywords: antibiotic resistance, cats, Dili, Escherichia coli, Salmonella spp. Yogyakarta.

Effects of different culture media on growth, composition, quality and palatability of the green algae Ulva sp. cultivated in cylindrical photobioreactors

Ulva spp. are valuable seaweeds with recognized commercial applications, including food, feed, and ecosystem services. Ensuring a sustainable and consistent supply of biomass with desirable profiles aligned with intended uses is fundamental for the successful applications of this seaweed. In this study, the growth rate, morphology, physiology, and composition of Ulva sp. produced by propagation in indoor cylindrical photobioreactors using four different culture media (lagoon water - LW, lagoon water enriched with Guillard medium (LF), with sea urchin wastewater - LU, and cow digestate - LD) was assessed; moreover, the nutrient uptake potential of the species was evaluated. The palatability and attractivity of the produced biomass towards the sea urchin Paracentrotus lividus were investigated. It was found that the media influenced all the parameters examined, the LF biomass weight was double compared to the other treatments and showed a slightly higher absorbance. Colorimetric analyses reported a significant darker color in Ulva sp. grown under enriched media. Ulva sp. showed higher nutrient removal potential in LF. The lipid content did not vary (2–3 % dry weight, DW), while the protein content ranged from 21 % in LF to 6–9 % in the other treatments. Carbohydrates and fiber content were significantly lower in LF (16 % and 30 %) compared to the other treatments, 27–34 %, and 41–48 %, respectively. Pigment content significantly varied, being higher in biomass grown in LF and LU. Sea urchins showed preferences for biomass grown under LU, followed by LD. This study shows how different nutrient sources affect the biochemical composition, growth, quality, and palatability of Ulva sp.. When cultivated under the synthetic enriched media (LF) the species exhibits characteristics better suitable for human consumption, although requiring a higher economic investment for production, while biomass derived from wastewater nutrients (LD, LU) confirms potential applications of the seaweed as valuable feed and for bioremediation services.

Optimizing phage-based mutant recovery and minimizing heat effect in the construction of transposon libraries in Staphylococcus aureus

Staphylococcus aureus (S. aureus), particularly Methicillin-resistant S. aureus (MRSA), poses a significant global public health threat, necessitating advanced methodologies to enhance our understanding of this organism at the omics levels. This study introduces a refined protocol for constructing and curing high-density transposon mutant (tn-mutant) libraries in S. aureus, addressing the challenges associated with low transductant yields, and the complex genetic manipulation mechanism in Gram-positive bacteria. Our methodology employs a Himar1 transposon based on a two-plasmid system, leveraging Himar1’s high insertional efficiency in AT-rich organisms. Enhanced transduction efficiency was achieved through chloramphenicol pre-treatment and the use of modified enriched media. Complementing this, an optimized plasmid curing procedure ensured a representative and stable tn-mutant library. The protocol was successfully applied to multiple S. aureus strains, demonstrating an increase in mutant recovery and reduced post-curing impact. The method offers a robust approach for Transposon Insertion Sequencing (TIS) applications in S. aureus, enabling deeper insights into survival, resistance, and pathogenicity mechanisms. This protocol holds a significant potential for accelerating the construction of tn-mutant libraries in various S. aureus strains.

Tumor Dormancy Within the Lymphovascular Embolus Is Regulated by Multiple Metabolism-signaling Pathways.

Recently, we demonstrated that cancer dormancy is initiated within the lymphovascular tumor embolus and consists of decreased proliferation and lower mammalian target of rapamycin (mTOR) activity. In the present study, we investigated other intersecting metabolism-signaling pathways that may ultimately determine whether the lymphovascular tumor embolus remains dormant or undergoes cell death. The present study exploited a singular patient-derived xenograft (PDX) of inflammatory breast cancer (Mary-X) that spontaneously forms high density spheroids, the in vitro equivalent of emboli. The AMPK metabolic checkpoint pathway, the mTOR nutrient-responsive cell growth pathway, the P13K/Akt intracellular quiescence regulating pathway, and the calpain-mediated E-cadherin proteolytic pathway responsible for spontaneous spheroid-genesis were also investigated, to determine their relative contributions to dormancy. The levels of phosphorylated AMPK proteins (AMPKα and β subunits) decreased gradually with the formation of MARY-X spheroids in vitro. Rapamycin down-regulated mTOR activity, yet dormancy persisted. LY294002, a PI3K/Akt inhibitor, completely abolished mTOR and induced spheroid disadherence and apoptosis. Compound C (AMPK inhibitor) up-regulated mTOR and induced spheroid disadherence and apoptosis. Increasing cellular metabolism led to cell death, even in enriched medium, whereas growing the spheroids in serum-free media (starvation) did not result in further mTOR inhibition, and dormancy was maintained. An increase in our understanding of dormancy from the standpoint of internal signaling pathways might ultimately provide clues to the external stimuli (starvation, hypoxia or other not yet understood phenomena) that act through these pathways to maintain or disrupt dormancy.

Incidence of Typhoid Fever Infection among Febrile Patients attending FUDMA Clinic

Typhoid fever remains a public health concern in Nigeria, with its incidence poising substantial challenges to health care systems. Widal agglutination test is largely the only used diagnostic test method for the laboratory diagnosis of Typhoid infection which has been proven to be neither sensitive nor specific. This paper delves into the incidence, contributory factors as well as sensitivity and specificity of commonly used diagnostic tests of typhoid fever infection among febrile patients attending the FUDMA Clinic. A total of 55 Blood and stool samples were analyzed using standard procedures for slide agglutination test (Widal) and stool culture, before culturing, the samples were first inoculated in an enrichment medium (Selenite-F broth). After 4 hours of pre-enrichment, the samples were inoculated into Salmonella Shigella Agar and Mackonkey agar, while catalase, TSI, citrate utilization test, Indole test, and urease tests served to identify the organism biochemically. Socio-demographic data revealed that 55 Participants, 52.8% were males, 72.7% were students and 80% were singles. Slide agglutination test recorded a 90.9% incidence rate, stool culture had an incidence rate of 18.18%. Among the age groups that enrolled in this study, a 44.1% incidence rate was recorded among the age Group 20-26 years. Stool culture was to found have performed better diagnostically with a sensitivity of 60% as well as a specificity of 40%. Conclusively, A high Incidence of typhoid fever was observed in this study. This Therefore suggests that there is an urgent need for improved personal hygiene and more accessibility to potable drinking water.

Synthesis and release studies on amylose-based ester prodrugs of fenamic acid NSAIDs.

Aim: To achieve colon-targeted release of mefenamic acid from its ester-linked amylose prodrugs.Materials & methods: The prodrug was characterized by 1H NMR and IR spectroscopy. Drug activation and release profile was studied in enzyme enriched simulated physiological media via UV-vis spectroscopy and was validated with HPLC analysis. ELISA assay was employed for evaluating the % inhibition of COX-1 and COX-2 inhibition at different concentrations of the prodrug preincubated with ester and/ or amylose hydrolyzing enzymes. SEM studies further validated the performance of the prodrug under simulated physiological conditions.Results: Pancreatin was essential for the prodrug activation in SIM to make the ester bonds in prodrug vulnerable to hydrolysis by esterase. This evidence was confirmed by drug release studies, HPLC analysis, ELISA assay and SEM investigation where the ester conjugated prodrug showed marked stability in physiological media only to get activated in the presence of amylose degrading enzyme.Conclusion: Ester linked amylose-mefenamic acid conjugate showed both enzyme responsive activation and release in SIM.

Antimicrobial Susceptibility of Commensal Escherichia coli from Pig Fecal Samples and Enhanced Sensitivity for Direct Detection of the blaCTX-M Gene by Nested PCR.

The commensal Escherichia coli in the gut of pigs is a major reservoir of antimicrobial resistance and can result in possible transmission to humans through the food chain. Direct detection of E. coli from fecal samples is challenging and can be used as a bioindicator of antimicrobial resistance. This study aimed to compare the antimicrobial susceptibility profiles in commensal E. coli from antibiotic- and nonantibiotic-using pig farms and developed the direct detection of ESBL genes in pig fecal samples using nested PCR (nPCR) and multiplex PCR (mPCR) techniques. All direct genotypic results were validated with the results of PCR sequencing of isolated E. coli colonies. The ESBL-producing E. coli were found in 98.6% (145 isolates) and 96.6% (144 isolates) of antibiotic-using and nonantibiotic-using farms, respectively, predominantly CTX-M-55. The nPCR decreased the limit of detection (LOD) from sPCR about 100 times, and the lower LODs of 102, 101, and 1 CFU/mL were reached after incubating samples in an enrichment medium for 2, 4, and 8 h, respectively. The mPCR, sPCR, and nPCR techniques showed sensitivities of 30.15%, 69.85%, and 91.91%, respectively, compared to PCR sequencing. The stability and recycling of ESBL genes were independent of antibiotic usage in commensal E. coli originating in pig farms.

Efficient and sensitive quantification of polar tobacco volatile organic compounds by a micro thermal-assisted sampling device using reduced graphene oxide coupling with thermal desorption-gas chromatography/mass spectrometry

AbstractIt still remains a great challenge to selectively enrich and sensitively quantify the trace volatile organic compounds (VOCs) in real samples with complex matrix. In this study, an integration method combining a selective enrichment medium of reduced graphene oxide (rGO) with a specially designed micro thermal-assisted purge-and-trap sampling device was developed for efficient enrichment and sensitive quantification of trace tobacco VOCs coupling with thermal desorption (TD)-gas chromatography/mass spectrometry (GC/MS). The prepared rGO has been proved to possess excellent enrichment selectivity and capacity for tobacco polar VOCs with the multi-layer structure, good thermal stability and large specific surface area. The specially designed sampling device was efficient and suitable for enriching and sampling trace polar tobacco VOCs coupling with rGO medium. Under the optimized sampling and analytical conditions, the established analytical method could be actually applied for quantification of typical tobacco polar VOCs with the good recoveries of 72.9–128% and the satisfied RSDs of 1.8–19.9% (n = 3). The results suggested that the developed method was selective, sensitive and reliable for enrichment and quantification of trace tobacco polar VOCs.

A comprehensive environmental analysis of heavy metal contamination, ecological risks and health impacts in Ilokun area, Ado-Ekiti, Nigeria

Heavy metal contamination in ecosystems is a global environmental and health concern. This study assessed the ecological and health risks associated with heavy metal pollution in farmland, dumpsite, stream land, and plant roots in Ilokun, Ekiti State, Southwest Nigeria. Samples were collected from different locations and analyzed for levels of heavy metal concentrations of cadmium (Cd), lead (Pb), manganese (Mn), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) using atomic absorption spectrophotometer. Various pollution indices such as enrichment factor, contamination factor, and geo-accumulation index were employed. Ecological risk methods were used to investigate the pollution status, heavy metal sources, and health risks associated with urban soil. The results showed that the concentrations of these metals exceeded permissible levels at most sampling sites, indicating significant contamination of the samples. Manganese, Cu, Pb, and Zn were the dominant metals in our study, and overall, the following trend: Mn > Zn > Cr > Ni > Cu > Pb > Cd. The contamination factor revealed that Cu, Zn showed moderate contamination, and Pb, Ni, and Mn showed high soil contamination. The ecological risk assessment demonstrated that Pb and Ni were associated with high risks due to anthropogenic influences related to coal combustion, vehicle exhausts, and automobile brakes. The findings indicate severe heavy metal media enrichment in the study area, which may lead to adverse ecological effects and health risks.

Conditional Optimization of Single Cell Protein Production from Crude Oil by <i>Pseudomonas aeruginosa</i>

The study was carried out to investigate the possible biodegradation of crude oil as a carbon by the bacterium <i>Pseudomonas aeruginosa</i> isolated from marine environment (Ras El-Menkar- Benghazi- Libya) using basal yeast extract protease peptone-3 (BYP) enriched medium. The isolated bacterium was identified and characterized according to its cultural condition and microbial biochemical properties. Different experiments were developed throughout this study to stimulate bacterial growth and production of single cell protein (SCP). The results show that the optimal concentration of crude oil as a carbon source for the highest bacterial growth (1.14g/l), and production of SCP (0.65g/l; 57.02% of the biomass dry weight) was 1%. This was required to utilize up to 50.6% of oil as a carbon source. As to the nitrogen source, the optimal concentration of ammonium chloride was 0.1%, in which the bacterial growth and SCP production increased to 1.23 g/l and 0.67 g/l respectively. The stimulating effects of organic and inorganic factors on the bacterial growth and SCP production was also tested. Addition of inorganic nutrients such as potassium phosphate (0.05%), magnesium sulphate (0.01%), and organic nutrient in the form of yeast extract (0.1%) to the fermentation medium slightly promoted the bacterial growth which reflected positively on SCP production and the percentage of the consumed crude oil, (>57%) at final pH value of 8.0. The obtained results indicated that the isolated<i> Pseudomonas aeruginosa</i> posses the ability to utilize the crude oil and use it as a carbon for bacterial growth and production of SCP.

Rapid and Sensitive Detection of Shiga Toxin-Producing Escherichia coli (STEC) from Food Matrices Using the CANARY Biosensor Assay.

Shiga toxin-producing Escherichia coli (STEC) causes a wide spectrum of diseases including hemorrhagic colitis and hemolytic uremic syndrome (HUS). Previously, we developed a rapid, sensitive, and potentially portable assay that identified STEC by detecting Shiga toxin (Stx) using a B-cell based biosensor platform. We applied this assay to detect Stx2 present in food samples that have been implicated in previous STEC foodborne outbreaks (milk, lettuce, and beef). The STEC enrichment medium, modified Tryptone Soy Broth (mTSB), inhibited the biosensor assay, but dilution with the assay buffer relieved this effect. Results with Stx2a toxoid-spiked food samples indicated an estimated limit of detection (LOD) of ≈4 ng/mL. When this assay was applied to food samples inoculated with STEC, it was able to detect 0.4 CFU/g or 0.4 CFU/mL of STEC at 16 h post incubation (hpi) in an enrichment medium containing mitomycin C. Importantly, this assay was even able to detect STEC strains that were high expressors of Stx2 at 8 hpi. These results indicate that the STEC CANARY biosensor assay is a rapid and sensitive assay applicable for detection of STEC contamination in food with minimal sample processing that can complement the current Food Safety Inspection Service (US) methodologies for STEC.

Impact of Paenibacillus elgii supernatant on screening bacterial strains with potential for biotechnological applications

The biotechnological industry faces a crucial demand for novel bioactive compounds, particularly antimicrobial agents, to address the rising challenge of bacterial resistance to current available antibiotics. Traditional strategies for cultivating naturally occurring microorganisms often limit the discovery of novel antimicrobial producers. This study presents a protocol for targeted selection of bacterial strains using the supernatant of Paenibacillus elgii, which produces abundant signal molecules and antimicrobial peptides. Soil samples were inoculated in these enriched culture media to selectively cultivate bacteria resistant to the supernatant, indicating their potential to produce similar compounds. The bacterial strains isolated through this method were assessed for their antibacterial activity. In addition, the functional annotation of the genome of one of these strains revealed several gene clusters of biotechnological interest. This study highlights the effectiveness of using this approach for selective cultivation of microorganisms with potential for biotechnological applications.

Dynamic Adhesive Behavior and Biofilm Formation of Staphylococcus aureus on Polylactic Acid Surfaces in Diabetic Environments.

Interest in biodegradable implants has focused attention on the resorbable polymer polylactic acid. However, the risk of these materials promoting infection, especially in patients with existing pathologies, needs to be monitored. The enrichment of a bacterial adhesion medium with compounds that are associated with human pathologies can help in understanding how these components affect the development of infectious processes. Specifically, this work evaluates the influence of glucose and ketone bodies (in a diabetic context) on the adhesion dynamics of S. aureus to the biomaterial polylactic acid, employing different approaches and discussing the results based on the physical properties of the bacterial surface and its metabolic activity. The combination of ketoacidosis and hyperglycemia (GK2) appears to be the worst scenario: this system promotes a state of continuous bacterial colonization over time, suppressing the stationary phase of adhesion and strengthening the attachment of bacteria to the surface. In addition, these supplements cause a significant increase in the metabolic activity of the bacteria. Compared to non-enriched media, biofilm formation doubles under ketoacidosis conditions, while in the planktonic state, it is glucose that triggers metabolic activity, which is practically suppressed when only ketone components are present. Both information must be complementary to understand what can happen in a real system, where planktonic bacteria are the ones that initially colonize a surface, and, subsequently, these attached bacteria end up forming a biofilm. This information highlights the need for good monitoring of diabetic patients, especially if they use an implanted device made of PLA.

First star formation in extremely early epochs

Abstract First stars play crucial roles in the development of the Universe, influencing events like cosmic reionization and the chemcal enrichment of the intergalactic medium. While first stars are conventionally thought to form at around $z \sim 20$–30 in the standard $\Lambda$ cold dark matter ($\Lambda$CDM) cosmology, observational constraints on small-scale ($\\lt $Mpc) density fluctuations remain limited, possibly differing significantly from the scale-invariant fluctuations assumed in the $\Lambda $CDM model. Should this be the case, the formation of first stars could occur much earlier than typically predicted. In this study, we investigate the formation process of first stars in the extremely early epochs of $z \gtrsim 100$ in the post-recombination Universe. At such early times, the effects of the warm cosmic microwave background (CMB) become significant. We calculate the collapse of primordial star-forming clouds using a one-zone thermo-chemical model that accounts for CMB influences on radiative heating, Compton cooling, and photodissociation reactions. We found that the impact of the CMB on the evolution is limited at $z \lesssim 100 $, with the temperature evolution closely resembling the conventional model. However, within the range $100 \lesssim z \lesssim 400$, the formation of H$_{2}$ via the H$^{-}$ channel is impeded by H$^{-}$ photo-detachment induced by the CMB, leading to higher temperatures compared to standard thermal evolution. Consequently, first stars with masses exceeding $1000\, {M}_{\odot }$ can emerge at $z \gtrsim 100$. Furthermore, at $z \gtrsim 500$, the temperature evolution becomes nearly isothermal at several thousand Kelvin solely due to atomic cooling, as H$_{2}$ formation is entirely suppressed, including the less-efficient H$_2^{+}$ channel, which is blocked by H$_2^{+}$ photodissociation. In such cases, supermassive stars with masses around $\sim 10^{5}\, {M}_{\odot }$ are expected to form solely via atomic cooling. These findings emphasize the significant variation in the typical mass of the first stars depending on the epoch of formation.