Hepatitis B virus (HBV) remains a major global health concern, and occult HBV infection (OBI) presents significant diagnostic and clinical challenges, particularly among hemodialysis (HD) patients. This study is aimed at characterizing complete HBV genomes from maintenance HD patients with OBI in Bangladesh to elucidate genetic features, mutational patterns, and clinical implications. Serum samples from two HBsAg-negative HD patients were screened by ELISA and quantitative PCR. Viral DNA was amplified by PCR across four overlapping open reading frames (ORFs) and sequenced on the Illumina platform. Genome assembly, phylogenetic analysis, and mutational profiling were performed using reference datasets and bioinformatics tools. Antigenicity and hydrophilicity of HBsAg were predicted in silico. Both patients were anti-HBc and anti-HBs positive with high HBV DNA loads (2.29 × 1010 and 2.53 × 1010 copies/mL). Full-length genomes (3182 bp) were successfully sequenced and phylogenetic analysis showed both HBV genomes clustered within Genotype D, Subgenotype D2, and subtype ayw3, consistent with previously reported Bangladeshi HBV genomes. Comparative mutational analysis identified substitutions such as T1753C in the basal core promoter, C1845T in preC, and D144E within the "a" determinant of HBsAg, suggesting potential roles in vaccine escape, immune escape, and diagnostic failure. Several nonsynonymous mutations were also detected in polymerase, though none were potentially associated with antiviral resistance. Antigenicity and hydrophilicity profiles of HBsAg and its major hydrophilic region remained largely conserved. These findings demonstrate the persistence of OBI in HD patients and provide an initial indication of the need for genomic surveillance to monitor immune-escape mutations and improve HBV diagnostic strategies in endemic regions.
Congenital central hypoventilation syndrome (CCHS) is a genetic disorder caused by mutations in the PHOX2B gene, characterized by impaired autonomic control of breathing and systemic consequences that may affect gut homeostasis. This study provides the first integrated multi-omics analysis in a CCHS group and matched controls, combining fecal DNA-based gut taxonomic profiling with targeted quantification of fatty acids and aromatic carboxylic acids. While overall microbial diversity and community structure remained largely preserved, significant alterations were observed in specific taxa within the CCHS group. Notably, the control group exhibited an enrichment of short-chain fatty acid (SCFA)-producing genera, which are associated with eubiotic gut ecosystems, whereas the CCHS group showed higher abundance of taxa commonly linked to inflammatory contexts. Consistently, fecal levels of beneficial SCFAs-particularly valeric acid, and to a lesser extent butyric acid-were reduced in CCHS group. These findings point to a dysbiotic gut microbiota in patients with CCHS, likely supporting putative inflammatory processes that would further worsen overall health status if confirmed. Furthermore, this work provides exploratory functional signatures for future studies aimed at understanding systemic consequences, guiding mechanistic investigations, and informing strategies to improve supportive care and long-term health outcomes in this rare patient population.
The rapid rise of multidrug-resistant (MDR) Klebsiella pneumoniae has created a major global health challenge due to the limited availability of conserved therapeutic targets effective across diverse resistant strains. In this study, an integrative computational target-discovery and drug-repurposing framework was applied to six clinically relevant K. pneumoniae strains. Comparative genomic analysis identified 3012 conserved genes, which were subsequently filtered to nine essential, non-host homologous proteins. Among these, three conserved cytoplasmic proteins (accD, cpxR, and mraZ) were prioritized for functional analysis, with acetyl-CoA carboxylase subunit beta (accD) emerging as the most promising therapeutic target based on sequence conservation, predicted essentiality, subcellular localization, and pathway association. Structural assessment supported the reliability of the predicted accD model, whereas consensus binding-site analysis identified key residues suitable for ligand interaction. Virtual screening of FDA-approved drugs followed by molecular docking identified several compounds with favorable binding profiles toward accD. Subsequent molecular dynamics simulations, including root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), hydrogen-bond occupancy, principal component analysis (PCA), and PCA-based free energy landscape (FEL) analyses, consistently identified tenapanor, micafungin, deferoxamine, and cobicistat as the most stable protein-ligand complexes, with tenapanor exhibiting the most favorable overall structural and thermodynamic stability profile. These findings identify accD as a promising therapeutic target in MDR K. pneumoniae and suggest several FDA-approved compounds as potential candidates for drug repurposing. Although experimental validation is needed to confirm their biological activity and therapeutic potential, this study demonstrates the potential of integrating comparative genomics with molecular dynamics analyses to support antimicrobial target identification and drug repurposing against MDR bacterial pathogens.
Immunostimulants are widely used in aquaculture to prevent diseases and have also been observed to promote growth in aquatic animals. The current study investigated the growth-promoting mechanism of dietary peptidoglycan (PG) in black tiger shrimp (Penaeus monodon). PG was supplemented into the experimental diets at varying concentrations (0.00, 0.10, 0.20, and 0.40 g·kg-1 of feed) and administered to the shrimp over a 60-day feeding trial. Shrimp growth in terms of weight gain and specific growth rate, total feed intake, feed conversion efficiency, protein efficiency ratio, and survival was monitored during the feeding trial. Immune parameters and shrimp viral resistance against white spot syndrome virus (WSSV) were also assessed. Results showed that supplementation of 0.20 g PG kg-1 diet enhanced shrimp growth compared with the control. This is supported by the biochemical analyses (nutrient retention, feed digestibility, digestive enzyme activities, and cellular energy allocation) showing improved feed conversion efficiency and lipid retention resulting from improved apparent dry matter digestibility of the diet, enzyme activities, and energy allocation in shrimp provided with 0.20 g PG kg-1 diet compared with the control. Furthermore, the 0.20-g PG kg-1 diet also resulted in the highest survival rate in the WSSV challenge test compared with the control and other PG-treated diets. This enhanced resistance was associated with an elevated total hemocyte count, increased respiratory burst activity, and increased phenoloxidase activity compared with the control. Collectively, the present data suggest that immunostimulant supplementation at 0.20 g PG kg-1 diet has growth-promoting effects in juvenile P. monodon.
Community carriage of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli represents an important reservoir of antimicrobial resistance. However, the genomic diversity and population structure of ESBL-producing E. coli circulating in community settings remain poorly characterized. This study aimed to characterize ESBL-producing E. coli isolated from fecal samples of residents in Ecuador, with an emphasis on the diversity and genomic context of ESBL genes. ESBL-producing E. coli was isolated from fecal samples obtained from 55 residents using MacConkey agar supplemented with cefotaxime. Whole-genome sequencing of the isolates was performed using a hybrid approach combining long- and short-read platforms. Plasmids and β-lactamase genes were identified using DFAST and PlasmidFinder. Bacterial identification and antimicrobial susceptibility testing were conducted by MALDI-TOF MS and the broth microdilution method, respectively. ESBL-producing E. coli were isolated from 35 of 55 fecal samples (63.6%). Complete circular genomes were obtained from 31 isolates. All isolates harbored bla CTX-M genes, predominantly belonging to the bla CTX-M-1 group, whereas 65.7% carried bla TEM, mainly bla TEM-1, and related variants. Although β-lactamase genes were predominantly plasmid-borne, chromosomal integration was detected in 40% of the isolates. Notably, 87.5% of the isolates harbored IncF plasmids with multiple replicons. Conserved IS26-flanked transposons carrying bla CTX-M and bla TEM were frequently identified in the plasmids. Phylogenetic analysis revealed substantial genomic diversity across seven phylogroups, together with closely related isolates detected within and between households. These findings provide high-resolution genomic insights into the ESBL determinants circulating in community residents and reveal region-specific patterns of ESBL genomic diversity.
Pseudomonas aeruginosa is an important cause of surgical site infections (SSIs) and is characterized by extensive antimicrobial resistance and genomic plasticity. We analyzed 13 whole-genome sequences of clinical P. aeruginosa isolates recovered from SSIs at a Level 5 referral hospital in Western Kenya and integrated genomic analyses with antimicrobial susceptibility tests and phenotyping of quorum-sensing (QS). Multidrug resistance was common, with resistance observed primarily against ciprofloxacin, piperacillin, ceftazidime, and amikacin, whereas meropenem and piperacillin/tazobactam retained the greatest in vitro activity. Genomic analyses identified diverse sequence types, extensive variability in insertion sequences and genomic islands, and widespread conservation of intrinsic resistance determinants, whereas accessory antimicrobial resistance genes were infrequently detected and largely associated with genomic islands. Virulence-associated genes were predominantly chromosomal, although several showed strain-specific genomic island localizations. Functional QS analyses demonstrated that isolates with intact lasR and rhlR produced significantly higher levels of acyl-homoserine lactone signals than isolates carrying predicted loss-of-function mutations, whereas Pseudomonas quinolone signal production remained comparatively conserved. These findings provide a genomic baseline for P. aeruginosa causing SSIs in Western Kenya and highlight the importance of integrating whole-genome sequencing with phenotypic analyses to strengthen surveillance and inform antimicrobial stewardship and infection prevention strategies.
Shiga toxin-producing Escherichia coli (STEC) colonizes the bovine recto-anal junction (RAJ), a key step in STEC pathogenesis in cattle, associated with animal disease, persistence, fecal shedding, carcass contamination, and zoonotic transmission. However, early adhesion mechanisms at the bovine RAJ remain insufficiently characterized, particularly among serotypes lacking the Locus of Enterocyte Effacement (LEE), referred to as LEE-negative strains. This study investigated strain-dependent epithelial interaction patterns at the bovine RAJ using complementary in vitro, ex vivo, and transcriptional approaches. Four representative strains were selected for functional assays, including two LEE-positive strains (O157:H7 and O26:H11) and two LEE-negative strains (O113:H21 and O130:H11). All strains adhered to primary bovine RAJ squamous epithelial cells, although no significant quantitative differences were detected among strains. In RAJ explants, however, LEE-positive strains showed epithelial association extending beyond the superficial layer, with immunolabeling distributed across the epithelial regions, whereas LEE-negative strains showed a predominantly superficial distribution. This pattern, not previously described in bovine RAJ explants, expands the current view of STEC colonization as a uniformly superficial epithelial process. Analysis of selected adhesion-related genes revealed strain-dependent transcriptional responses to the RAJ environment. LEE-positive strains showed higher expression of eae, together with increased expression of iha, csgD, and pgaA. In contrast, LEE-negative strains showed lower expression of these genes and consistent expression of saa, supporting the existence of distinct epithelial interaction strategies that may reflect strain-specific behaviors among circulating LEE-positive and LEE-negative isolates. Overall, these findings demonstrate distinct epithelial interaction and transcriptional profiles among STEC strains and show that physiologically relevant tissue models can reveal serotype-dependent colonization patterns not fully captured in simplified cell systems and may support the identification of potential targets for vaccine-based intervention strategies in cattle.
Ascidians are filter-feeding marine invertebrates that display inter- and intraspecific color variation and host diverse microbiomes. Although color variation has been used as an indicator of speciation and correlated with distinct microbiome structure in some colonial species, there is limited research on microbiome variation across color morphs and body regions in solitary ascidians. To address these knowledge gaps, three color morphs (purple, orange, and intermediate shades of pink) of the solitary Belizean ascidian Rhopalaea abdominalis were collected for phylogenetic analysis using the Cytochrome Oxidase I (COI) gene and for microbial characterization via sequencing the V4 region of the 16S rRNA gene. Microbial sequences derived from the ascidian branchial sac, gut, and tunic body regions were processed using both operational taxonomic unit (OTU) and amplicon sequence variant (ASV) pipelines to determine the resolution and consistency of sequence processing methods using mothur and QIIME 2 software, respectively. COI sequencing revealed two clades that were independent of color morphs. Microbiome characterization showed no significant differences in alpha- or beta-diversity across ascidian color morphs or COI clades but distinct microbiomes within each body region. The branchial sac harbored a higher number of core members (i.e., detected across all host individuals) that included known ascidian symbionts (e.g., Endozoicomonas), whereas the gut and tunic were colonized by taxa identified in seawater and across multiple classes of marine invertebrates. Results were highly congruent between OTU- and ASV-based pipelines, yielding statistically equivalent alpha-diversity metrics, consistent beta-diversity patterns, and similar core membership profiles. These findings reinforce the validity of both methods for studying microbial symbiont communities and corroborate previous research showing distinct microbiomes by body region and overall conservation when color morphs lack genetic differentiation.
Tropical peatlands are among the largest global carbon sinks and face increasing impacts from drainage, fire, and land-use change. These disturbances modify soil physicochemical characteristics and influence bacterial community structure. However, the response of bacterial communities to these changes is incompletely understood. This study examined bacterial community composition at six peatland sites in the Giam Siak Kecil-Bukit Batu Biosphere Reserve, Riau, Indonesia. The sites represent various land-use types: secondary forest, restored peat, burned peat, oil palm, rubber, and acacia plantations. The analysis employed 16S rRNA gene sequencing combined with measurements of soil physicochemical properties. Results showed that key bacterial phyla, such as Acidobacteriota, Pseudomonadota, and Actinomycetota, were consistently found across sites, though their relative abundances varied. Burned sites had increased abundances of Bacillota and other copiotrophic groups and decreased abundances of several oligotrophic taxa. Beta diversity analysis showed differences in community patterns among sites, but multivariate analysis did not show significant differences between land-use types. Variation in bacterial community composition is associated with soil pH and nutrient availability, including available phosphorus, exchangeable potassium, and exchangeable magnesium, although these relationships are not always statistically supported. A small number of ASVs were detected across all sites, suggesting overlapping community members amid high spatial heterogeneity. Overall, tropical peatland bacterial communities form within a narrow environmental framework in which distinctive physicochemical properties constrain which microbes can survive. Land-use changes are primarily associated with shifts in the relative abundance of bacterial taxa rather than complete community turnover. Given the limited number of samples and single time-point observations, these findings are exploratory and provide a basis for further research.
Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of multidrug-resistant and biofilm-associated infections, particularly on indwelling medical devices, where conventional antibiotics often exhibit limited efficacy. In this study, we isolated and characterized a novel lytic bacteriophage, SA_SGEB_01, targeting MRSA from hospital wastewater in Bangladesh. Biological characterization demonstrated that SA_SGEB_01 possesses favorable therapeutic properties, including a short latent period (~45 min), a burst size of approximately 91 plaque-forming units per infected cell, and stability across a broad pH range (3-11) and temperatures up to 45°C. Host range analysis revealed lytic activity against MRSA and methicillin-resistant Staphylococcus saprophyticus. Whole-genome sequencing showed that SA_SGEB_01 contains a linear double-stranded DNA genome of 18,031 bp with no detectable lysogeny-associated, antibiotic resistance, or virulence genes, supporting its therapeutic suitability. Comparative genomic and phylogenetic analyses classified the phage within the genus Rosenblumvirus of the family Rountreeviridae. Phage-antibiotic checkerboard assays demonstrated strong synergistic activity between SA_SGEB_01 and ciprofloxacin, with fractional inhibitory concentration index values below 0.5. Importantly, SA_SGEB_01 significantly reduced biofilm biomass in both 24- and 48-h-old MRSA biofilms and achieved approximately a 2-log10 reduction of viable cells in in vitro silicone catheter-associated biofilms, whereas vancomycin did not produce a statistically significant reduction under the same experimental conditions. To our knowledge, this is the first biologically and genomically characterized S. aureus phage from Bangladesh with demonstrated activity against MDR MRSA biofilms, highlighting its potential as a promising candidate for controlling device-associated MRSA infections.
The growing threat of antimicrobial resistance (AMR) among foodborne pathogens poses a significant public health risk in South Africa, largely driven by excessive antibiotic use in dairy farming practices. This study investigated the virulence and AMR profiles of Escherichia coli isolated from bovine quarter milk samples in the Dr. Kenneth Kaunda District, North West Province, South Africa. Sixty-five E. coli isolates were confirmed using the automated identification Sensititre ARIS 2X ID/AST System and PCR targeting the uidA gene. Serogrouping revealed a predominance of non-O157 strains, with O128 (50.8%) as the dominant serogroup, followed by O145 (9.2%), whereas 40% of isolates were nontypable, highlighting serotype diversity. The fliC gene encoding flagellin was the most prevalent virulence marker (62.5%), whereas stx1 was detected in 9.2% of isolates, and stx2 was absent. Phenotypic testing demonstrated high resistance to amoxicillin/clavulanic acid and cephalothin (58.9% each), tetracycline (37.8%), and trimethoprim-sulfamethoxazole (3.3%). However, no isolates exhibited phenotypic multidrug resistance (MDR), despite 98.5% harboring one or more resistance genes: ermB (92.3%), vanB (90.8%), tetM (56.9%), and ampC (10.8%). The high prevalence of ermB and vanB may indicate coselection of resistance determinants and suggests their potential association with mobile genetic elements that facilitate dissemination among bacterial populations. These findings indicate that E. coli from bovine milk in the region serve as silent reservoirs for virulence and resistance genes. These findings are vital for managing E. coli isolates in dairy farming and taking proactive measures to limit AMR in animals.
Background:Candida is one of the most common causes of bloodstream infections in critically ill and immunocompromised patients. Understanding the distribution and antifungal resistance patterns of Candida species and the associated mortality rates is critical for tailoring therapeutic measures. Objectives:The aim of this study is to analyze the epidemiology, antifungal resistance trends, and risk factors influencing mortality associated with candidemia in a tertiary healthcare center of Saudi Arabia. Patient and Methods:The study included all cases of bloodstream infections caused by Candida species from December 2021 to January 2023. The antifungal susceptibility and identification of species were done via standard protocols. Univariate and multivariate statistical analyses were conducted to determine the predictors of 14-day mortality (death within 14 days of the first positive blood culture) and overall (in-hospital) mortality (death during the index hospitalization). Results:Fifty patients were included in the study with a median age of 71 years, with 58% being females. C. albicans accounted for 21.3% of candidemia cases, with a declining trend over time. Candidozyma auris (formerly Candida auris) was the most frequently identified non-albicans Candida species (25%). Fluctuating trends in antifungal susceptibility of non-albicans Candida were observed, with increasing resistance to azoles, while increasing susceptibility to micafungin. The 14-day mortality and overall (in-hospital) mortality rates were 23.4% and 55.3%, respectively. Multivariate analysis revealed older age, cardiac and respiratory disorders, ICU as site of diagnosis, treatment duration of > 48 h, and Candida colonization to be independent predictors of overall (in-hospital) mortality (p < 0.05). Conclusion:The continuous rise of antifungal resistance and spread of non-albicans Candida species highlight the need for implementing rigorous control measures in healthcare facilities. Improving candidemia outcomes requires prompt identification of high-risk patients and targeted therapies.
Antimicrobial resistance (AMR) in foodborne pathogens represents a major public health concern, particularly in traditional animal-derived foods. This study investigated the occurrence of β-glucuronidase-positive Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) in 121 meat products and 328 cheeses produced in the province of Cosenza (Calabria, Southern Italy). Microbiological analyses were performed according to ISO 16649-2:2001 and ISO 6888-2:2021, and isolates were biochemically confirmed using the Vitek 2 System. Thirty cheese samples exceeded regulatory limits for coagulase-positive staphylococci, while 29 showed elevated Escherichia coli counts, likely associated with raw milk use and artisanal processing. Among meat products, only two fresh sausages tested positive for Escherichia coli, suggesting contamination linked to inadequate sanitation of casings. Statistical analyses revealed significantly higher positivity rates for both microorganisms in cheese compared with meat products. These findings highlight the need for improved hygiene practices, continuous monitoring, and targeted interventions to reduce microbial contamination in traditional foods. Enhanced surveillance is also essential to track the emergence and dissemination of MRSA in the food chain.
Meningitis, an acute and life-threatening inflammation of the protective membranes covering the brain and spinal cord caused primarily by bacterial, viral, fungal, or parasitic infections, remains a major global health challenge, causing significant morbidity and mortality, particularly among children and vulnerable populations. The Sri Lankan epidemiological unit reported approximately 1000-1500 meningitis cases annually. This review summarizes current knowledge on meningitis in Sri Lanka, drawing on global evidence and locally published studies to examine epidemiology, clinical presentation, diagnostic approaches, immunity gap, and future priorities. Most studies indicate that bacterial meningitis, particularly caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae, remains the most severe and clinically significant form. Viral etiologies, especially enteroviruses, are also commonly reported. Although the introduction of the H. influenzae Type b (Hib) vaccine has significantly reduced disease burden, important immunity gaps persist due to limited pneumococcus serotype coverage and the absence of routine meningococcal vaccination. Diagnostic challenges, including delays in cerebrospinal fluid collection, limited access to molecular testing, and preanalytical errors, hinder early detection and accurate pathogen identification. Future directions should focus on strengthening molecular diagnostic capacity, strengthening point-of-care rapid antigen assays and decentralized molecular diagnostics, expanding serotype surveillance, improving sample collection practices, and evaluating the feasibility of introducing meningococcal vaccination into the national immunization schedule. Bridging these gaps is essential for aligning Sri Lanka's efforts with global targets outlined in the World Health Organization's (WHO) Defeating Meningitis by 2030 roadmap.
Brucellosis is a neglected zoonosis with a considerable disease burden in livestock-dependent areas. Khuzestan Province, southwestern Iran, exhibits diverse ecological and agricultural landscapes that may drive heterogeneous transmission. Knowledge of recent epidemiological trends is important for targeted control. We aimed to characterize the temporal and demographic patterns of human brucellosis in Khuzestan from 2017 to 2024, with emphasis on changes observed after 2021. We analyzed aggregated surveillance data for all laboratory-confirmed human brucellosis cases reported in Khuzestan Province between 2017 and 2024. Crude annual incidence rates were calculated using population denominators linearly interpolated from the 2017 census and the 2023 official estimate. Log-linear trend regression, performed using Joinpoint software, estimated the annual percentage changes (APCs) in incidence case counts. Poisson's regression with population offset quantified period relative risks (RRs) comparing 2022-2024 with 2017-2021. Chi-square tests assessed temporal shifts in distributions across age groups (15 categories), sex, residence (rural/urban/nomadic), and four geographical zones (Northern Highlands, Central Plains, Southern Coastal and Marshland, and Western Borderlands). A total of 3923 cases were reported. Crude incidence remained stable at 7.9-8.1 per 100,000 during 2017-2019, declined to 6.3-7.0 in 2020-2021, and then increased sharply to 12.3-14.7 in 2022-2024 (APC = +10.7%; 95% CI: 2.2-19.9; p = 0.019). Incidence during 2022-2024 was 1.66 times higher than during 2017-2021 (95% CI: 1.52-1.81; p < 0.001). The largest relative increases in reported case counts were in adults aged ≥ 70 years (APC = +21.1%; 95% CI: 11.1-32.2) and in adults aged 65-69 years (+20.0%, 9.9-31.1), whereas children aged 0-4 years showed no significant change. The male-to-female ratio shifted from 0.88 in 2017 to 1.22 in 2024 (p = 0.032), driven by a significant rise in male cases (APC = +11.5%, p = 0.011) against a nonsignificant female increase. Rural cases increased significantly (APC = +11.2%, p = 0.009), accounting for 47%-61% of annual cases. The Northern Highlands zone bore 62.7% of total cases (APC = +11.6%, p = 0.003); the Southern Coastal zone exhibited the steepest relative increase (APC = +15.8%, p = 0.020). Although statistically significant, changes in composition over time were small in magnitude (Cramér's V = 0.06 - 0.12). Human brucellosis in Khuzestan Province has resurged dramatically since 2021, with a 66% increase in period risk. The epidemiological profile shifted to older adults, males, and people living in rural areas, with marked geographical heterogeneity. The results emphasize the need for targeted vaccination of livestock in high-burden areas (Northern Highlands and Southern Coastal), enhanced surveillance in older age groups, and increased One Health approaches to reverse this trend.
Paronychia represents an underexplored clinical condition with limited alternatives to conventional antimicrobial therapies, which are increasingly compromised by antibiotic resistance and toxicity. Here, we report for the first time the extracellular biosynthesis of silver nanoparticles (BAgNPs) using Bacillus stercoris 2AT10, a marine-derived bacterium not previously exploited for nanoparticle production. By integrating green nanotechnology with genome mining approaches, we investigated the molecular basis underlying nanoparticle formation and evaluated the potential of BAgNPs against pathogens associated with paronychia. Physicochemical characterization by ultraviolet-visible (UV-Vis) spectroscopy confirmed the presence of particles, with mean sizes ranging from 47 to 87 nm measured by dynamic light scattering (DLS). Their spherical shape was confirmed by transmission electron microscopy (TEM), whereas Fourier-transform infrared (FTIR) spectroscopy suggested the presence of hydroxyl, amide, and nitrogen-containing groups possibly associated with reducing or capping action. Genes encoding nitrate reductases, laccases, and bioactive secondary metabolites, such as bacillibactin, subtilosin A, bacillaene, bacilysin and fengycin, that may be involved in silver ion reduction and nanoparticle stabilization were identified by genome annotation using eggNOG-mapper and antiSMASH. The biosynthesized AgNPs exhibited potent broad-spectrum antimicrobial activity against paronychia-associated pathogens, notably with inhibition zones of 25.8 mm for Staphylococcus aureus and of 23.2 mm for Pseudomonas aeruginosa. The Hen's Egg Test on the Chorioallantoic Membrane (HET-CAM) assay showed the nonirritating profile of the biosynthesized particles (irritation index ≤ 1), supporting further investigation of their suitability for topical applications, pending additional biocompatibility studies. Collectively, these findings establish B. stercoris-derived BAgNPs as a promising green nanotechnology platform to address the unmet need for safe and effective prophylactic agents against bacteria associated with paronychia, with additional potential as antimicrobial preservatives for dermocosmetic formulations.
This study is aimed at isolating and characterizing antimicrobial peptides (AMPs) from the leaves of Capsicum annuum (L.) cv. Carioquinha and investigating their antifungal activity and mechanism of action against phytopathogenic fungi. An initial extract was obtained from leaves through hydromethanolic extraction followed by partitioning with dichloromethane. The extract was resuspended in aqueous acetonitrile and centrifuged to obtain the soluble supernatant fraction (ExS). The ExS fraction was purified by reverse-phase high-performance liquid chromatography (RP-HPLC). Protein bands from the ExS fraction were excised from Tricine-SDS-PAGE gels and analyzed by LC-MS/MS. The obtained peptide sequences were compared with protein databases. Antifungal activity of the ExS fraction was evaluated through quantitative fungal growth inhibition assays against the phytopathogenic fungi Fusarium solani, Fusarium oxysporum, Colletotrichum gloeosporioides, and Colletotrichum scovillei, and tests were conducted to investigate the mechanism of action of the peptides present in the ExS fraction. RP-HPLC analysis of the ExS fraction revealed a single peak (P1) corresponding to a protein band of approximately 6.5 kDa, and all fragments obtained by LC-MS/MS were similar to peptides belonging to the hevein-like family. The highest inhibition was observed for C. gloeosporioides, with 78.3% growth inhibition at 200 μg mL-1. Mechanistic studies revealed that the ExS fraction caused membrane permeabilization in C. gloeosporioides, induced reactive oxygen species (ROS) production, and reduced cell viability. The ExS fraction also caused vacuolization of hyphae in F. oxysporum. This study highlights the potential of AMPs isolated from C. annuum leaves to inhibit phytopathogenic fungi.
Pleurotus eous (P. eous) contains a range of bioactive metabolites with reported antimicrobial and antioxidant potential. This work describes the green synthesis of silver nanoparticles using an aqueous extract of P. eous and evaluates their physicochemical features and in vitro antimicrobial activity. Silver nanoparticles were formed through fungal extract-mediated reduction of silver nitrate, with UV-visible spectroscopy showing a surface plasmon resonance band around 420 nm. FTIR analysis indicated the involvement of fungal biomolecules in reduction and stabilization, while XRD confirmed the crystalline, face-centered cubic structure of metallic silver. FE-SEM imaging revealed predominantly spherical nanoparticles with an average size of 39 ± 7.6 nm. The methanolic extract of P. eous showed strong antioxidant activity, with DPPH radical scavenging reaching 97.39%, and contained measurable phenolic content (1.02 ± 0.07 mg GAE g-1 dry weight), as supported by GC-MS profiling. Antimicrobial testing demonstrated that the biosynthesized silver nanoparticles exhibited moderate inhibitory effects against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, Candida tropicalis, and Aspergillus niger, with inhibition zones of 11.8-16.3 mm for bacteria and 13.3-14.3 mm for fungi at 250 μg. While less potent than conventional antimicrobials, these nanoparticles demonstrated measurable activity, warranting detailed toxicity and in vivo evaluation.
Microbially induced carbonate precipitation (MICP) is a recognized bioremediation strategy for mitigating toxic metal pollution; however, the relative contributions of bioprecipitation, biosorption, and bioaccumulation to cadmium (Cd) removal during MICP remain underexplored. This study assessed Cd immobilization by six rhizosphere ureolytic bacterial strains from different genera in liquid medium and quantified the metal distributed among the bioprecipitated, biosorbed, and bioaccumulated fractions. Minimum inhibitory concentration assays showed Cd tolerance ranging from 90 to 300 mg L-1. The strains presented total Cd removal efficiencies of 64.9%-99.8% within 120 h. Notably, Cd removal occurs mainly under 48 h. Biosorption assays revealed substantially lower Cd removal compared with bioprecipitation experiments. Comparative analysis of Cd bioprecipitation and biosorption assays, combined with sequential extraction, demonstrated that bioadsorption plays a significant role in the removal of Cd via MICP. Precipitates characterization further confirmed coprecipitation of Cd with vaterite, a calcium carbonate polymorph. These findings elucidate an important role of biosorption in Cd immobilization during MICP, highlighting the need to evaluate removal mechanisms when assessing bacterial MICP potential, as different mechanisms can lead to distinct long-term stability outcomes.
Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by microbial imbalance, particularly the overgrowth of Staphylococcus aureus. This study reports the green synthesis of silver nanoparticles (AgNPs) using Macaranga tanarius extract (MTE) and evaluates their in vitro antibacterial and bioactive properties. The synthesized MT-AgNPs exhibited a distinct surface plasmon resonance (SPR) peak at 430 nm, with TEM revealing predominantly spherical morphologies (mean size: 29.2 nm; range: 6-87 nm). Phytochemical analysis confirmed that MTE is rich in polyphenols (2429 ± 33.7 mg GAE/100 g) and flavonoids (236.3 ± 10.7 mg QE/100 mL), contributing to its strong antioxidant capacity (82.72% ± 3.12% DPPH scavenging; FRAP: 20.36 ± 0.02 mg FeSO4/100 mL). MT-AgNPs demonstrated potent antibacterial activity against 17 clinical S. aureus isolates (e.g., mecA-positive strains), with MICs of 9.375-18.75 μg/mL. At 6.25 μg/mL, MT-AgNPs significantly inhibited biofilm formation by up to 63% (p < 0.05). Crucially, MTE displayed a highly stable tyrosinase inhibitory profile, maintaining a consistent inhibition rate of approximately 45% throughout a 120-min kinetic assay (equivalent to 6.0-8.5 mg kojic acid/g). This sustained inhibitory stability suggests its potential application in addressing postinflammatory hyperpigmentation. These findings indicate that MT-AgNPs serve as a promising, eco-friendly antibacterial nanomaterial with potential in vitro applications for managing AD-related microbial challenges and skin recovery.
