Bacterial Culture Research Articles

Enhanced Extracellular Electron Transfer in Magnetite-Mediated Anaerobic Oxidation of Methane Coupled to Humic Substances Reduction: The Pivotal Role of Membrane-Bound Electron Transfer Proteins.

Humic substances are organic substances prevalent in various natural environments, such as wetlands, which are globally important sources of methane (CH4) emissions. Extracellular electron transfer (EET)-mediated anaerobic oxidation of methane (AOM)-coupled with humic substances reduction plays an important role in the reduction of methane emissions from wetlands, where magnetite is prevalent. However, little is known about the magnetite-mediated EET mechanisms in AOM-coupled humic substances reduction. This study shows that magnetite promotes the reduction of the AOM-coupled humic substances model compound, anthraquinone-2,6-disulfonate (AQDS). 13CH4 labeling experiments further indicated that AOM-coupled AQDS reduction occurred, and acetate was an intermediate product of AOM. Moreover, 13CH313COONa labeling experiments showed that AOM-generated acetate can be continuously reduced to methane in a state of dynamic equilibrium. In the presence of magnetite, the EET capacity of the microbial community increased, and Methanosarcina played a key role in the AOM-coupled AQDS reduction. Pure culture experiments showed that Methanosarcina barkeri can independently perform AOM-coupled AQDS reduction and that magnetite increased its surface protein redox activity. The metatranscriptomic results indicated that magnetite increased the expression of membrane-bound proteins involved in energy metabolism and electron transfer in M. barkeri, thereby increasing the EET capacity. This phenomenon potentially elucidates the rationale as to why magnetite promoted AOM-coupled AQDS reduction.

Comparative analysis of the transcriptomes from regenerated plants and root explants of endangered Oplopanax elatus.

Oplopanax elatus is a plant of therapeutic significance in oriental medicine; however, its mass cultivation is limited owing to the difficulties in propagating it from seeds. In this study, we investigated the transcriptome profiles and transcriptional regulatory factors expressed during plantlet regeneration from root tissues of the endangered O. elatus. The RNA-seq results for the control and regenerated plants cultured in liquid medium for 8weeks showed that the clean length of the control group was 11,901,667,912 and that of the 8-week sample was 10,115,155,171, indicating a clean value of 97% for both samples. The number of mapped paired-end reads was 63,922,480 for the control group and 54,146,902 for the 8-week sample. The number of genes for which at least one clean data point was mapped was 43,177 in the control group and 42,970 in the 8-week sample. The results of the differentially expressed gene analysis indicate that the number of upregulated genes in the 8-week sample was 158, and the number of downregulated genes was 424. Gene Ontology (GO) analysis of the upregulated genes revealed that GO terms were classified into 14 categories, and genes expressed in the biological process category occurred most frequently. GO terms of the downregulated genes were evenly distributed into two categories: biological process and molecular function. From the upregulated genes, eight reference genes with significant differences in expression were selected and analyzed using real-time PCR. The Oe38836 gene (late embryogenesis abundant protein M17-like isoform X1) showed the highest expression rate that was more than tenfold that of the control. Oe40610 (auxin-responsive protein SAUR21-like) and Oe07114 (glucose-1-phosphate adenyl transferase-like protein) genes showed expression levels that were increased eightfold relative to the control. The RNA sequencing (RNA-seq) results from the plants regenerated through liquid culture of O. elatus root tissue were confirmed using real-time PCR, indicating their reliability.

Mitigation of heavy metal toxicity in pigeon pea by plant growth promoting Pseudomonas alcaliphila strain PAS1 isolated from contaminated environment.

The risk of arsenic contamination is rising globally, and it has negative impacts on the physiological processes and growth of plants. Metal removal from contaminated soils can be accomplished affordably and effectively with plant growth promoting rhizobacteria (PGPR)-based microbial management. From this angle, this research evaluated the mitigation of arsenic toxicity using the bacteria isolated from contaminated site, Mettur, Salem district, South India. The newly isolated bacterial strain was screened for plant growth promotion potential and arsenic tolerance such as (100ppm, 250ppm, 500ppm, 800ppm and 1200ppm). The metal tolerant rhizobacteria was identified using 16S rRNA gene sequence analysis as Pseudomonas alcaliphila strain PAS1 (GenBank accession number: OQ804624). Pigeon pea (Cajanus cajan) plants were used in pot culture experiments with varying concentrations of arsenic, (5ppm, 10ppm and 25ppm) both with and without bacterial culture, for a period of 45days. At the concentration of 25ppm after the application of PAS1 enhanced the plant growth, protein and carbohydrate by 35.69%, 18.31% respectively. Interestingly, P. alcaliphila strain PAS1 significantly reduced the stress-induced elevated levels of proline, flavonoid, phenol and antioxidant enzyme in pigeon pea plants was 40%, 31.11%, 27.80% and 20.12%, respectively. Consequently, PAS1 may significantly reduce the adverse effects that arsenic causes to plant development in acidic soils, improve plant uptake of nutrients, and increase plant production. The findings of this study reveal that P. alcaliphila PAS1 is intrinsic for phytoremediation by reducing arsenic accumulation in the root and shoot.

A novel, simple and rapid assay to measure citrate level in bacterial culture for analysis of citrate consumption by bacteria

Citrate is essential for Krebs cycle in eukaryotes and serves as a carbon source for some bacteria to survive/grow. Available methods for measuring citrate level rely mainly on enzymatic reactions and/or sophisticated instrumentations. This study aimed to develop a novel, simple and rapid assay to quantify citrate in bacterial culture for analysis of citrate consumption. The assay was initially tested with 0.1–25.6 mM citrate in deionized (dI) water or complete M9 medium without/with 0.25 M HCl. Wavelength scan revealed maximum absorption of citrate at λ210 nm with linear calibration curve (R2 = 0.9997–0.9999) when HCl was added. Among negatively charged chemicals tested, only oxalate interfered with the assay. After 24-h inoculation of Klebsiella pneumoniae (the known citrate-utilizing bacterium) in (20 mM) citrate-containing complete M9 medium, the remaining citrate significantly decreased (by 22.20±7.13 % consumption). However, a mild decrease was also observed in the sample without bacterial inoculation, suggesting that some components of the complete medium interfered with the assay. It was clearly evidenced that M9 salt, CaCl2 and/or MgSO4 were responsible for such interference. Finally, citrate at low concentrations (0.1–6.4 mM) in M9 medium with CaCl2 and/or MgSO4 provided the linear calibration curve (R2 = 0.9451–0.9986). At 5 mM, citrate consumption by K. pneumoniae after 24-h culture was 46.88±0.47 %. In summary, we have successfully developed a novel, simple and rapid method for measuring citrate level in bacterial culture. It will be very useful for measuring citrate consumption by typical and atypical citrate-utilizing bacteria for classification, mechanistic and pathophysiologic studies.

Bacterial Culture Results and Antibiograms in Chronic Rhinosinusitis Patients in Mekong Delta, Vietnam

Background The inappropriate use of antibiotics for chronic rhinosinusitis, exceeding established guidelines, is a growing concern in Vietnam. This practice is contributing to the emergence and spread of antibiotic-resistant bacteria. Objective This study aimed to evaluate the results of culture and antibiogram of bacteria on patients in the Mekong Delta, Vietnam, who were treated for chronic rhinosinusitis in 2022-2023. Methods It is a cross-sectional study, including 113 patients who came for treatment with a diagnosis of chronic rhinosinusitis at Can Tho University of Medicine and Pharmacy Hospital, Mekong Delta, Vietnam, from 2022-2023. The bacterial cultures were identified, and their antibiograms were performed in the Microbiology laboratory of Can Tho University of Medicine and Pharmacy. Statistical analysis was performed with SPSS version 20.0. Results The rate of bacterial growth was 97.35%. The cultured bacterial composition had 8 genera, 22 species, and 116 samples, of which 2 bacterial species were cultured, accounting for 5.45%. Antibiogram showed that Streptococcus pneumonia was resistant to cefaclor (83.33%), cefuroxime (100%), trimethoprim+ sulfamethoxazole (100%), and susceptible to chloramphenicol (100%) and vancomycin (100%). Streptococcus haemolyticus was resistant to amoxicillin+clavulanic acid (85.71%) and ampicillin (100%) and susceptible to linezolid (100%) and rifampin (100%). Streptococcus epidermidis was resistant to amoxicillin+clavulanic acid (82.35%), ampicillin (100%), penicillin (100%) and susceptible to linezolid (91.18%) and rifampin (88.24%). Streptococcus aureus was resistant to amoxicillin+clavulanic acid (95%) and ampicillin+sulbactam (90%), and susceptible to linezolid (90%) and synercid (95%). Pseudomonas aeruginosa was resistant to amikacin (100%), meropenem (100%) and tobramycin (90%). Conclusion This study offers some useful information to doctors in the Mekong Delta and across Vietnam. It can be used as a good orientation in choosing the most appropriate antibiotics for treating patients with chronic rhinosinusitis. It is important to be conscious of the current trend of the bacteriological profiles and to regulate the antibiotic treatment regime to improve the effectiveness and reduce antibiotic resistance rate.

Rheological Properties and Sensory Profile of Yoghurt Produced with Novel Combination of Probiotic Cultures

Novel probiotic yoghurt was produced using the combination of bacterial cultures Lactobacillus plantarum HA119 and Bifidobacterium animalis subsp. lactis B94 and yoghurt bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Its basic nutritional composition, colour, texture, rheological properties, and sensory profile were compared with yoghurt produced using the same technological process and standard yoghurt cultures (control sample), as well as other commercially available yoghurts with different milk fat contents. Despite the fat content of the yoghurt made with the new probiotic cultures being 1.44%, its apparent viscosity was similar to that of high-fat yoghurt (2.99%). Other results from rheological measurements indicate that the new yoghurt had a stronger protein network, presumably due to the higher number of exopolysaccharides compared to both control and commercial yoghurts. Sensory analysis revealed that there were no statistically significant differences between the novel probiotic yoghurt and high-fat yoghurt as perceived by panellists. In conclusion, this combination of probiotic cultures can be used to produce yoghurt with rheological and sensory properties similar to high-fat yoghurts, without the need for hydrocolloids or changes in the production process.

Role of DNA Double-Strand Break Formation in Gyrase Inhibitor-Mediated Killing of Nonreplicating Persistent Mycobacterium tuberculosis in Caseum.

Tuberculosis is the leading cause of mortality by infectious agents worldwide. The necrotic debris, known as caseum, which accumulates in the center of pulmonary lesions and cavities is home to nonreplicating drug-tolerant Mycobacterium tuberculosis that presents a significant hurdle to achieving a fast and durable cure. Fluoroquinolones such as moxifloxacin are highly effective at killing this nonreplicating persistent bacterial population and boosting TB lesion sterilization. Fluoroquinolones target bacterial DNA gyrase, which catalyzes the negative supercoiling of DNA and relaxes supercoils ahead of replication forks. In this study, we investigated the potency of several other classes of gyrase inhibitors against M. tuberculosis in different states of replication. In contrast to fluoroquinolones, many other gyrase inhibitors kill only replicating bacterial cultures but produce negligible cidal activity against M. tuberculosis in ex vivo rabbit caseum. We demonstrate that while these inhibitors are capable of inhibiting M. tuberculosis gyrase DNA supercoiling activity, fluoroquinolones are unique in their ability to cleave double-stranded DNA at low micromolar concentrations. We hypothesize that double-strand break formation is an important driver of gyrase inhibitor-mediated bactericidal potency against nonreplicating persistent M. tuberculosis populations in the host. This study provides general insight into the lesion sterilization potential of different gyrase inhibitor classes and informs the development of more effective chemotherapeutic options against persistent mycobacterial infections.

Case report: Mycobacterium chimaera-induced lymph node infection in a patient with chronic myeloproliferative neoplasm misdiagnosed as tuberculous lymphadenitis

Herein, we report a case of lymphadenitis caused by Mycobacterium chimaera. A 54-year-old woman with chronic myeloproliferative neoplasm was admitted to the hospital with cervical lymphadenopathy. After preliminary exclusion of various diseases such as lymphoma, Epstein–Barr virus infection, and autoimmune disease, a lymph node biopsy specimen showed epithelioid granulomatous lymphadenitis with caseous necrosis, epithelial-like cells, and multinucleated giant cells as seen in tuberculosis (TB). Although Mycobacterium tuberculosis was never isolated, diagnostic anti-TB treatment was commenced. Following over 9 months of treatment, there was no significant reduction in the size of her cervical lymph nodes, and she continued to experience recurrent low-grade fevers. One sample from the fourth lymph node biopsy tested negative for metagenomic next-generation sequencing (mNGS), and another sample tested positive in the BACTEC MGIT960 liquid culture system, identifying the strains as Mycobacterium chimaera. Anti-non-tuberculous mycobacteria (NTM) therapy was initiated, and the patient achieved symptom improvement. In conclusion, NTM lymphoid infection is easily misdiagnosed as long-term etiologic negativity.

Dark tourism, thana tourism, and ghost tourism: a bibliometric visualization review for the last 23 years (2000–2023)

PurposeThis study uses bibliometric visualization techniques to comprehensively review the intertwined concepts of dark tourism, thana tourism and ghost tourism from 2000 to 2023. The research seeks to clarify the ambiguity and inconsistencies arising from the interchangeable use of these terms and sets forth a roadmap for future research endeavors.Design/methodology/approachThis study meticulously extracts research keywords from 634 scholarly papers in the Scopus database. It undertakes a thorough bibliometric analysis utilizing the visualization of similarities (VOS) viewer and RStudio to map the interconnectedness of these tourism phenomena.FindingsThe study identifies and explores contemporary theories such as self-categorization theory, stimulus-organism-response theory, embodiment theory, self-determination theory, socio-cognitive theory, risk perception theory, services theory, dark tourism theory, social and cultural theory, push-pull theory, performance theory, and wound culture theory. The research reveals four primary clusters through keyword co-occurrence and bibliographic coupling analyses: dark tourism insights, dynamics of dark tourism, dark tourism review and dark tourism experiences, illustrating their interrelationships and robustness.Practical implicationsDark tourism insights can guide ethical practices, ensuring respectful site management and accurate historical representation. Integrating dark tourism into broader destination strategies can diversify offerings, attract niche markets and contribute to preserving historical memory through reflective experiences.Originality/valueThis study's outcomes significantly contribute to tourism literature by enhancing our understanding of the overlapping terminologies associated with dark, thana and ghost tourism. This improved comprehension sheds light on the importance of the research agenda surrounding the concept of dark, thana and ghost tourism.

Reduction of misdiagnosis in urinary tract infections during pregnancy: The role of adjusted urine flow cytometry parameters.

Urinary tract infections (UTIs) pose a significant health concern, particularly among pregnant women, for whom accurate diagnosis is essential. However, the use of Urine flow cytometry (UF) for detecting UTIs in this demographic often results in misdiagnosis. The objective of this study was to explore the reasons behind these diagnostic errors and to develop a strategy to minimize the rate of UTI misdiagnosis in pregnant women. The study enrolled 1,200 women aged 18 to 40 years, categorized into pregnant and non-pregnant groups. UTIs were diagnosed using urine bacterial culture, microscopic examination, and UF, followed by statistical analysis to identify any discrepancies in diagnosis between the groups. Following the calibration of UF analyzer's parameters, the most effective CR(WBC)-CW-FSC-P Gain setting for diagnosing UTIs in pregnant women through UF was ascertained by applying the Youden index. The clinical diagnosis rate of UTIs was significantly higher in pregnant women (40.91%) compared to non-pregnant women (20.26%). However, urine microscopy and bacterial culture showed no significant difference in the rates of UTIs between the two groups, suggesting a potential for misdiagnosis. The false-positive rate for WBCs detected by UF was 30.43%, and adjusting the CR(WBC)-CW-FSC-P Gain value of UF reduced the false-positive rate to 9.45%. The incidence of UTIs in pregnant women may be overestimated because of the limitations inherent to UF. Adjusting the parameters of the UF analyzer, particularly the CR(WBC)-CW-FSC-P Gain value, can significantly reduce the rate of UTI misdiagnosis in pregnant women.

A comparative evaluation of the antimicrobial efficacy of triple antibiotic paste, clindamycin, and linezolid as an intracanal medicament against Enterococcus faecalis: An in vitro study

ABSTRACT Aim: The aim of the present study was to evaluate and compare the antimicrobial efficacy of three medicaments, triple antibiotic paste (TAP), clindamycin (CLID), and linezolid (LZ) against Enterococcus faecalis, using spectrophotometry. Methods: Seventy-two single-rooted human premolars were collected and prepared using standard protocol and were decoronated to obtain standardized lengths. A pure culture of E. faecalis (ATCC 29212) was procured, grown on blood agar, obtained using a wired loop, and suspended in brain heart infusion (BHI) broth for 24 h. After contaminating the canals with E. faecalis, the prepared samples were divided into three groups, with 24 teeth each, based on the intracanal medicament used, Group A: TAP (ciplox×500 mg, metrogyl 400 mg, minoz 100 mg) + normal saline (NS), Group B: CLID (capsule clid 150) + NS, Group C: LZ (Lizoforce, dry syrup) + NS. The medicaments were syringed into the roots and which were then incubated. After 24 h, 12 samples per group were thoroughly rinsed for removal of intracanal medicaments (ICMs), and instrumented using #4 GG drill to obtain dentinal shavings, which were allowed to fall into sterile BHI broth. The turbidity of the broth was assessed and the optical density (OD) was recorded using spectrophotometer to estimate the concentration of E. faecalis after 1 day. After a period of 7 days, the remaining 12 samples per group underwent identical processing. Results: At the end of day 1, all three antibiotics presented comparable values of OD indicating comparable antimicrobial efficacy. Group-wise comparison revealed that TAP continued to be superior to the other two antibiotics even at the end of 7 days. However, the difference was significant only between TAP and LZ with no significant difference between TAP and CLID and between CLID and LZ. Conclusion: The present study concludes that the use of single-antibiotic CLID and LZ may serve as an effective alternative to the multidrug combination TAP, as an ICM.

Metabolome Shift in Centella asiatica Leaves Induced by the Novel Plant Growth-Promoting Rhizobacterium, Priestia megaterium HyangYak-01.

Centella asiatica, a traditional herb, is widely recognized for its pharmacologically active components, such as asiaticoside, madecassoside, asiatic acid, and madecassic acid. These components render it a highly sought-after ingredient in various industries, including cosmetics and pharmaceuticals. This study aimed to enhance the production and activity of these pharmacological constituents of C. asiatica using the plant growth-promoting rhizobacterium Priestia megaterium HyangYak-01 during its cultivation. To achieve this goal, the researchers conducted field experiments, which revealed an increase in the production of pharmacologically active compounds in C. asiatica cultivated with a P. megaterium HyangYak-01 culture solution. Additionally, quadrupole time-of-flight mass spectrometry (Q-TOF MS) confirmed that the composition ratios of the C. asiatica extract treated with the P. megaterium HyangYak-01 culture solution differed from those of the untreated control and type strain-treated groups. Skin cell experiments indicated that the C. asiatica extract treated with the P. megaterium HyangYak-01 culture solution exhibited greater skin barrier improvement and less pronounced inflammatory responses than those from plants grown without the bacterial culture solution. This study demonstrates that microbial treatment during plant cultivation can beneficially influence the production of pharmacological constituents, suggesting a valuable approach toward enhancing the therapeutic properties of plants.

Study of Escherichia coli, EPEC, ETEC AND STEC, in water offered in schools in a municipality with low human development index in Maranhão State, Brazil

This study examined the EPEC, ETEC and STEC pathotypes in E. coli isolates from water supplied to schools in a municipality in Maranhão, Brazil with a low human development index. For this, 57 bacterial strains isolated from 19 water samples were used. All strains were confirmed as belonging to the E. coli species, by Gram staining and phenotypic tests. From pure cultures of E. coli, DNA was extracted followed by characterization of the isolates by polymerase chain reaction (PCR). This is the first study carried out in the state of Maranhão on the research of the diarrheagenic strains EPEC, ETEC and STEC in water for human consumption offered in schools, with the detection of virulent genes characteristic of enterotoxigenic E. coli (26.31%; n = 15/57) and E. coli producing Shiga toxin (8.78%; n= 5/57). Of the strains identified, 8.78% (n= 5/57) corresponded to combinations of est + stx1 genes. It is concluded that the detection of the diarrheagenic strains ETEC and STEC in E. coli isolates from water samples for human consumption indicates that, in addition to the water being contaminated, it harbors strains with pathogenic potential to cause diarrheal infection in its users. Keywords: ETEC, school environment, STEC.

An outbreak of acute diarrhoeal disease caused by Shigella sonnei in a village in Dibrugarh district, Assam

Background & objectives Food and waterborne illnesses remain a neglected public health issue in India. Events with large gatherings frequently witness outbreaks of acute diarrheal diseases due to consumption of contaminated food or water or poor food handling practices. In the present study, an outbreak of acute diarrhoeal disease (ADD) occurring among the attendees of a birthday party in rural Dibrugarh district in the northeastern Indian State of Assam was investigated. Methods Sociodemographic information along with details of ADD outbreak that included information about source of foods, food handlers, illness details, etc., were collected using an outbreak investigation form for descriptive and analytical epidemiology. Rectal swabs from affected individuals and food handlers were collected along with bore-well water samples and tested in the laboratory by performing bacterial culture, biochemical analysis and polymerase chain reaction. Due to the delayed report on the outbreak, collecting leftover food for laboratory testing and analysis was impossible. Results A total of 25 cases of ADD had similar signs and symptoms. The mean incubation period for developing acute diarrhoea was 26.36±8.76 (± standard deviation) hours from food consumption. The overall attack rate was 60.04 per cent (25/41); 20 per cent (5/25) required hospitalization. Thirteen rectal swab samples were tested for pathogens and found positive for Shigella sonnei. Antibiotic susceptibility test of isolated S. sonnei showed resistance to nalidixic acid, ciprofloxacin and cefotaxime. Consumption of one of the food items - chicken curry was significantly associated with illness (Odds Ratio=14.8; 95% Confidence Interval: 2.75-85.11); P value<0.05 and Population Attributable Fraction (PAF) was 70.18 per cent. The water samples were found satisfactory for human consumption. Interpretation & conclusions The findings suggested that S. sonnei infection could be implicated in the investigated food-borne diarrhoeal disease outbreak and that there was a potential for human-poultry cross-infection. Additionally, the study revealed concerning levels of S. sonnei resistance to recommended antibiotics and drew attention to their public health relevance.

Improving treatment plan and mental health in children with abdominal infection for broad-spectrum bacterial infections

BACKGROUND Pediatric abdominal infection is a common but serious disease that requires timely and effective treatment. In surgical treatment, accurate diagnosis and rational application of antibiotics are the keys to improving treatment effects. AIM To investigate the effect of broad-spectrum bacterial detection on postoperative antibiotic therapy. METHODS A total of 100 children with abdominal infection who received surgical treatment in our hospital from September 2020 to July 2021 were grouped. The observation group collected blood samples upon admission and sent them for broad-spectrum bacterial infection nucleic acid testing, and collected pus or exudate during the operation for bacterial culture and drug sensitivity testing; the control group only sent bacterial culture and drug sensitivity testing during the operation. RESULTS White blood cell count, C-reactive protein, procalcitonin, 3 days after surgery, showed better postoperative index than the control group (P < 0.05). The hospital stay in the observation group was significantly shorter than that in the control group. The hospitalization cost in the observation group was significantly lower than that in the control group, and the difference between the two groups was statistically significant (P < 0.05). CONCLUSION Early detection of broad-spectrum bacterial infection nucleic acids in pediatric abdominal infections can help identify pathogens sooner and guide the appropriate use of antibiotics, improving treatment outcomes and reducing medical costs to some extent.

N-linked protein glycosylation in Nanobdellati (formerly DPANN) archaea and their hosts.

Members of the kingdom Nanobdellati, previously known as DPANN archaea, are characterized by ultrasmall cell sizes and reduced genomes. They primarily thrive through ectosymbiotic interactions with specific hosts in diverse environments. Recent successful cultivations have emphasized the importance of adhesion to host cells for understanding the ecophysiology of Nanobdellati. Cell adhesion is often mediated by cell surface carbohydrates, and in archaea, this may be facilitated by the glycosylated S-layer protein that typically coats their cell surface. In this study, we conducted glycoproteomic analyses on two co-cultures of Nanobdellati with their host archaea, as well as on pure cultures of both host and non-host archaea. Nanobdellati exhibited various glycoproteins, including archaellins and hypothetical proteins, with glycans that were structurally distinct from those of their hosts. This indicated that Nanobdellati autonomously synthesize their glycans for protein modifications probably using host-derived substrates, despite the high energy cost. Glycan modifications on Nanobdellati proteins consistently occurred on asparagine residues within the N-X-S/T sequon, consistent with patterns observed across archaea, bacteria, and eukaryotes. In both host and non-host archaea, S-layer proteins were commonly modified with hexose, N-acetylhexosamine, and sulfonated deoxyhexose. However, the N-glycan structures of host archaea, characterized by distinct sugars such as deoxyhexose, nonulosonate sugar, and pentose at the nonreducing ends, were implicated in enabling Nanobdellati to differentiate between host and non-host cells. Interestingly, the specific sugar, xylose, was eliminated from the N-glycan in a host archaeon when co-cultured with Nanobdella. These findings enhance our understanding of the role of protein glycosylation in archaeal interactions.IMPORTANCENanobdellati archaea, formerly known as DPANN, are phylogenetically diverse, widely distributed, and obligately ectosymbiotic. The molecular mechanisms by which Nanobdellati recognize and adhere to their specific hosts remain largely unexplored. Protein glycosylation, a fundamental biological mechanism observed across all domains of life, is often crucial for various cell-cell interactions. This study provides the first insights into the glycoproteome of Nanobdellati and their host and non-host archaea. We discovered that Nanobdellati autonomously synthesize glycans for protein modifications, probably utilizing substrates derived from their hosts. Additionally, we identified distinctive glycosylation patterns that suggest mechanisms through which Nanobdellati differentiate between host and non-host cells. This research significantly advances our understanding of the molecular basis of microbial interactions in extreme environments.

Probiotic Properties of Lactobacilluscasei and L. plantarum Isolated From Overripe Avocado Pear

Probiotics have been researched for their benefit to gut health. Research for sources of probiotic bacteria has moved from milk to plants, as they have been found to be an inexhaustible source of lactic acid bacteria (LAB). The probiotic properties of lactic acid bacteria isolated from Over ripe Avocado pear on selected bacterial species were assessed. Fifty Unripe Avocado pears were purchased from different markets and allowed to ferment. Enumeration of the microorganisms and pure culture isolation were done on MRS agar supplemented with1.0% CaCO3 at 37 oC for 48 hours; using the pour plate and streak plate methods respectively. The isolates were identified based on their microscopic, macroscopic, biochemical and molecular characteristics. They include Lactobacillus casei and L. plantarum. LAB isolates were tested for their phenol tolerance, bile salt tolerance, acid tolerance and antimicrobial activity. All the isolates were tolerant to simulated gastrointestinal conditions. Growth of the isolates was observed at different temperature between 15 oC to 60 oC. They exhibited tolerance to phenol ranging from 0.085±0.01% to 2.40±0.02%. Tolerance to bile salt ranged from 1.06x101± 0.96x101 to 3.04x103±1.15x102. The acid tolerance level of the LAB obtained ranged from 2.98x102±1.30x102 to 8.78x102±2.22x102. Agar-well diffusion method was used to determine the antimicrobial susceptibility of the bacterial species. The test showed that the isolates were susceptible to the LAB isolates as zones of inhibition were observed. The inhibition zones diameter obtained ranged from 8.35±1.34mm to 13.77±2.21mm. Avocado pear, asides from their high nutritional content, also have the potential to serve as source of probiotic bacteria.

Antimicrobial resistance in <em>Staphylococcus aureus</em>, Enterobacterales, and <em>Pseudomonas</em> spp. clinical isolates at a Teaching Hospital in Sri Lanka

Background: Antimicrobial resistance (AMR) is a signifi-cant global health issue in the 21st century, posing a serious threat to human health.Objectives: This study was to determine the burden and predictors of AMR and multidrug resistance (MDR) among bacterial pathogens isolated from specimens submitted to the diagnostic laboratory of a hospital in Sri Lanka.Methodology: This retrospective study used laboratory records of 1,204 clinical specimens submitted for bacterial culture submitted to the diagnostic laboratory of Neville Fernando Teaching Hospital in Sri Lanka for bacterial culture and sensitivity testing between October 2021 and May 2024. Records from specimens positive for Enterobacteriaceae, Staphylococcus aureus, or Pseudomonas spp. isolates were included for analysis.Results: Number of samples which yielded Gram negative Enterobacterales was 758 (62.95%). Of these 499 (65.83%) were ESBL and 59 (7.78%) were carba-penemase producers. Among the 214 participants, Staphylococcus aureus was isolated from 206 (96.26%) participants. This included 74 (35.92%) participants who were colonized with Methicillin Resistant Staphylococcus aureus (MRSA) isolates and Methicillin Sensitive Staphylococcus aureus (MSSA) 132 (64.07%). Among Pseudomonas spp. isolates, 29.48% were resistant to one or more aminoglycosides, 29.48% were resistant to a fluoroquinolone and only 8.54% were resistant to carbapenems.Conclusion: This study shows that there is a high level of microbial resistance in Sri Lanka. The high levels of extended-spectrum cephalosporin resistance and multi-drug resistance (MDR) among Enterobacterales observed in this study are of concern. However, the relatively low levels of methicillin-resistant Staphylococcus aureus (MRSA) and MDR S. aureus, as well as the very low levels of carbapenem resistance among Pseudomonas spp. isolates, are encouraging.

Effectiveness of supplementary antimicrobial procedures in disinfecting lateral canals as evaluated by a novel ex vivo analytical approach

This ex vivo study devised an analytical ex vivo method for infection/disinfection of simulated lateral canals located in the middle and apical segments of the root. The antibacterial effects of supplementary approaches were tested in this model. Extracted mandibular premolars had their main root canals enlarged and then two lateral canals (100 μm in diameter) were created in the root, one in the apical and the other in the middle portion. Micro-computed tomography was used for specimen selection and to confirm the quality of the simulated ramifications. The specimens were contaminated with a mixed bacterial culture from subgingival bacterial biofilm added to pure Enterococcus faecalis strain ATCC 29212 grown overnight, using special strategies to facilitate culture medium penetration within the lateral canals. The following procedures were tested for disinfection: NaOCl/passive ultrasonic irrigation (PUI), NaOCl/XP-endo Finisher, ozonated water/continuous ultrasonic irrigation (CUI), and NaOCl/conventional irrigation with 30-G needles (control). Bacteriological samples were taken from the main canal before (S1) and after (S2) each supplementary protocol, and also from each lateral canal after treatment (S3). DNA extracted from the samples was subjected to quantitative real-time polymerase chain reaction. All S1 main canal samples were positive for bacterial presence. Bacterial counts in the main root canal substantially decreased by 99.2% after PUI, 99.1% after ozone/CUI, 99% after XP-endo Finisher, and 96% in the control group (P < 0.01 for all groups). There were no significant differences between groups (P > 0.05). The same was observed when comparing the effects of the supplementary approaches in the apical and middle lateral canals (P > 0.05). Only a few lateral canals showed no detectable bacteria. The method proposed here proved effective for ex vivo infection/disinfection studies. All supplementary approaches induced a substantial bacterial reduction in the main canal, with no significant differences between them. However, in terms of lateral canal disinfection, none of the tested approaches showed significant effects when compared to the control group.

Functional starter cultures for meat: a study of technological and probiotic characterisation

The use of starter cultures in meat product technology reduces process time and improves organoleptic performance. The selection of starter cultures involves various stages and is a rather complex process: preliminary characterization in laboratory conditions; selection of the most promising strains; laboratory verification and final verification in large-scale fermentation. Nowadays, the selection of a functional starter culture includes another step related to the evaluation of functional properties. This paper presents an example of using a stepwise approach to select promising starter cultures with probiotic abilities. Researchers obtained several types of pure bacterial cultures from a basic starter and determined indicators of enzymatic and technological activities. Proteolytic activity, nitrate reduction capacity, amount of mucus, pH change, temperature effect on growth, amount of salt, as well as probiotic traits: antibiotic resistance, survival in acidic medium, degree of interaction with water (hydrophobicity), degree of interaction with Salmonella and Escherichia coli were investigated in the isolated strains. The studies were carried out in comparison with some collection strains. As a result, strains from the base inoculate were capable of fermentation at low temperatures and exhibited a particular degree of bio activity, while specific probiotic characteristics in terms of hydrophobicity and survival under gut-mimicking conditions were identified for the collection strains.