International Journal of Microbiology最新文献

Despite the benefits of petroleum hydrocarbon as essential raw energy sources in many industries, they cause major global environmental pollution. Petroleum hydrocarbons pollutants are highly toxic and recalcitrant, making them dangerous and persistent over long periods in an ecosystem. However, oil contaminated soil is enriched with microorganisms that can utilize petroleum products and hydrocarbons for their growth, nutrition, and metabolic activities. This study aimed to isolate and characterize hydrocarbons-degrading bacteria capable of degrading hydrocarbons in soil samples obtained from oil-polluted garage sites in Kericho County, Kenya. One hundred and ten (110) bacterial isolates were isolated after enrichment, with 67 of the isolates (60.9%) having visible petroleum diesel-degrading capability. The bacteria were characterized based on phenotypic characteristics and 16S rRNA gene sequence analyses. Forty-nine of the isolates were Gram negative rods, and majority (56) of the isolates reacted positively for catalase and negatively for oxidase (38), methyl red (59), and Voges Proskauer (65); 50.9% of the isolates tested positive for citrate utilization. More than half of the isolated bacteria (69.7%) demonstrated strong evidence of diesel degradation. Bacteria with moderate diesel degradation demonstration accounted for 18.2% of the isolates, while isolates with substantial diesel residues contributed 12.1%. Following 16S rRNA gene sequence analysis, the bacterial strains were identified as belonging to the genera Acinetobacter (8), Pseudarthrobacter (4), Corynebacterium (2), Gordonia (2), Athrobacter (2), Microbacterium (2), Acidivorax (1), Pseudoxanthomonas (1), Priestia (1), Cellulosimicrobium (1), Cupriavidus (1), Paenarthrobacter (1), Exiguobacterium (1), Shewanella (1), Stutzerimonas (1), and Pseudomonas (1). This study has demonstrated that garage soils with petroleum hydrocarbon contamination in Kericho County harbor a rich and diverse indigenous population of microbes with the ability to biodegrade diesel. The findings suggest potential application of these bacterial strains to facilitate the biodegradation of petroleum hydrocarbons.

Biofilms are surface-attached bacterial communities that contribute significantly to chronic infections. Their altered metabolism promotes antibiotic resistance and makes treatment more difficult. Alternative strategies, such as the use of medicinal plants, are being actively investigated and Agrimonia eupatoria L. is one of them. This study is aimed at evaluating the antibiofilm activity of ethanol, acetone, and ethyl acetate extracts of A. eupatoria against Staphylococcus aureus, Proteus spp., and Pseudomonas aeruginosa strains isolated from human wounds. In addition, the effects of these extracts on bacterial auto-aggregation, surface hydrophobicity, and motility were investigated. The phytochemical analysis included FT-IR spectroscopy and spectrophotometric quantification of the total phenolic compounds. FT-IR analysis confirmed the presence of characteristic functional groups vibrations (O-H at ~3425 cm^-1, C=O at ~1735-1685 cm^-1, and aromatic C=C at ~1618-1515 cm^-1), whereas phytochemical profiling revealed that the ethyl acetate extract contained the highest phenolic acid content (149.65 ± 0.73 mg CAE/g). All tested extracts inhibited initial cell adhesion and biofilm formation, although they were less effective against mature biofilms. Among them, acetone and ethyl acetate extracts exhibited the strongest antibiofilm activity. S. aureus strains S1 and S2 were the most susceptible, with inhibition rates of at least 92% and 85% for the acetone extract, and 78% and 86% for the ethyl acetate extract, respectively. Although auto-aggregation and cell surface hydrophobicity remained unaffected, both swimming and swarming motilities were reduced. Finally, fluorescence microscopy confirmed that the inhibitory effect was dose-dependent. These results suggest that A. eupatoria extracts represent promising natural antibiofilm agents against clinically relevant human pathogens.

Aedes albopictus has recently established self-sustaining populations in Hungary, but its microbiota-which may influence vector competence-remains poorly understood. We used Oxford Nanopore long-read sequencing for full-length 16S rRNA gene profiling of adult Ae. albopictus from two urban sites, Pécs and Barcs. Each location contributed 10 specimens, with contamination controls rigorously applied. Diversity metrics and co-occurrence network analyses were performed using QIIME2, SparCC, and NetCoMi, with robustness assessed via simulated node removal and addition. Sequencing depth was sufficient to saturate rarefaction curves. Although alpha and beta diversity did not differ significantly between sites, the Pécs population exhibited greater taxonomic richness (100 unique taxa vs. 61 in Barcs) and denser, more clustered networks. Only 15 genera were shared, with Wolbachia dominating both communities. Networks differed in central taxa and structural properties: Pécs retained higher connectivity and shorter paths under perturbation, suggesting greater resilience. Removal of conserved taxa revealed location-specific impacts on network stability, with Pécs more vulnerable to the loss of key genera. Negative interactions and compensatory taxa emerged post-removal, indicating distinct reconfiguration strategies. Our findings highlight marked local variation in microbiome structure and robustness, even across a 65-km gradient. These results establish a high-resolution baseline for assessing how microbiota shape Ae. albopictus vector potential, informing microbiome-based control strategies tailored to regional contexts.

Objectives: Early diagnosis of bacterial sepsis remains a significant challenge in clinical practice, primarily due to the limitations of conventional methods such as blood culture, which require prolonged turnaround times and have low sensitivity. The real-time polymerase chain reaction (RT-PCR) method using CRownLab Pneumoplex was developed to enable rapid and simultaneous detection of pathogens. This study is aimed at evaluating the diagnostic validity of CRownLab Pneumoplex in detecting Klebsiella pneumoniae and Acinetobacter baumannii in patients with sepsis at a tertiary hospital in Indonesia.

Methods: This cross-sectional study involved 400 sepsis patients recruited between October 2024 and February 2025. Blood, sputum, urine, and pus specimens were collected from patients who met the inclusion and exclusion criteria. All samples were analyzed using culture methods as the gold standard and RT-PCR using CRownLab Pneumoplex. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated.

Results: RT-PCR detection of K. pneumoniae demonstrated a sensitivity of 89.0%, specificity of 87.7%, PPV of 65.2%, NPV of 96.9%, and accuracy of 88.0%. For A. baumannii, sensitivity was 92.9%, specificity was 88.9%, PPV was 23.2%, NPV was 99.7%, and accuracy was 89.0%. Overall, combined detection yielded a sensitivity of 88.9%, specificity of 87.0%, PPV of 69.3%, NPV of 96.0%, and diagnostic accuracy of 87.5%. For sputum specimens, sensitivity was 73.5%, specificity was 96.9%, PPV was 98.9%, NPV was 50.0%, and accuracy was 78.5%. The mortality rate among sepsis patients in this study was 69.5%.

Conclusions: The RT-PCR method using CRownLab Pneumoplex demonstrated high diagnostic validity for the detection of K. pneumoniae but only moderate reliability for A. baumannii. For sputum specimens, the RT-PCR method showed good diagnostic performance in patients with sepsis and respiratory infections.

Many antibiotics originate from soil-inhabiting Actinobacteria, especially from the diverse genus Streptomyces. However, the emergence of antibiotic resistance poses a significant global challenge to treating infectious diseases. Therefore, the search for Actinobacteria, particularly from less-explored environments, as potential sources of novel antimicrobial compounds, is of great importance. This study sampled various biofilms growing on cave structures within Deer Cave and Lagang Cave, located in the UNESCO World Heritage Site of Gunung Mulu National Park (GMNP; Sarawak, Malaysia). From this relatively untapped niche in caves, we identified and screened actinobacterial isolates for their potential antimicrobial properties against drug-resistant Pseudomonas aeruginosa and Staphylococcus aureus strains. Of 48 isolates, 24 showed inhibition of one or both drug-resistant strains in the antimicrobial assays conducted using cross-streak and agar well diffusion methods. The ethyl acetate extracts containing potential secondary metabolites demonstrated effective inhibition, particularly against the drug-resistant Gram-negative P. aeruginosa. In contrast, the supernatants obtained from aerobic cultivation exhibited comparatively better activity against Gram-positive S. aureus strains. 16S rRNA gene sequencing analysis of the isolates revealed that all except one isolate belonged to the genus Streptomyces. Maximum likelihood bootstrap tree analysis strongly supported the correct clustering of the Streptomyces isolates with well-known bioactive compound producers, such as S. gardneri, S. laurentii, and S. zaomyceticus. Notably, Deer Cave Isolate D3-12 exhibited inhibitory activity against both drug-resistant strains and, therefore, represents a promising candidate for future studies involving the characterization of its bioactive compounds. The remaining actinobacterial isolate exhibited 100% sequence homology to soil-inhabiting Rhodococcus pedecola, known for its antibacterial properties. These findings suggest that the caves of GMNP harbor untapped ecological niches of diverse cave-dwelling Actinobacteria, which may serve as sources of antimicrobial compounds effective against emerging antibiotic-resistant pathogens.

The rapid emergence of multidrug-resistant (MDR) pathogens, particularly in hospital wastewater, poses a serious threat to public health and emphasizes the need for alternative antimicrobial strategies. In this study, Enterococcus hirae, an environmentally derived strain, was used for the first time in the extracellular green synthesis of zinc oxide nanoparticles (ZnO NPs) and copper oxide/zinc oxide nanoparticles (CuO/ZnO NPs). The nanoparticles were characterized using standard techniques. Ultraviolet-visible (UV-Vis) spectra, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS) confirmed both nanoparticle formation, size, and morphology. Antimicrobial activity against Staphylococcus aureus (ATCC 6538), Morganella morganii, Kerstersia gyiorum, and Klebsiella pneumoniae was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays, showing a 62.5% greater efficacy of bimetallic NPs than ZnO alone. The 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) assay revealed that E-CuO/ZnO NPs exhibited superior antioxidant activity with the lowest IC₅₀ of 5.528 μg/mL, outperforming E-ZnO NPs, which is attributed to the synergistic effect between ZnO and CuO NPs. The combination of E-ZnO and E-CuO/ZnO nanoparticles with ciprofloxacin (CIP) and ceftazidime (CAZ) was evaluated against MDR isolates. Synergistic interactions were observed particularly against K. pneumoniae. This study confirms effective E. hirae-mediated synthesis and the enhanced antibacterial and antioxidant potential of CuO/ZnO NPs, supporting eco-friendly strategies against MDR infections, with synergistic interactions observed with conventional antibiotics, particularly against K. pneumoniae, indicating that the nanoparticles can enhance antibiotic efficacy.

Klebsiella pneumoniae is associated with high antimicrobial resistance and is commonly isolated from colonization and healthcare-associated infections (HAIs). This study is aimed at developing and validating molecular assays to detect resistance genes belonging to the bla family in resistant K. pneumoniae isolates. The genes included belong to the subfamilies: blaSHV, blaTEM, blaNDM, blaKPC, blaGES, blaCTX-M, and relevant variants of the blaOXA subfamily. The identified genotypic profile showed a high prevalence of genes belonging to Ambler's classes of beta-lactamases A, B, and D, which was in accordance with the phenotypic results obtained for the isolates investigated. A high prevalence of resistance to penicillins, cephalosporins, and carbapenems was observed. In conclusion, the assays developed were efficient in detecting the main resistance genes of the bla family in K. pneumoniae, revealing a concerning regional burden of resistance genes.

Indigenous backyard poultry is the predominant type of poultry in developing countries. Rural smallholder farmers in these regions usually adopt the free-range (backyard) production system, which exposes the poultry to diverse environments and a broad spectrum of microorganisms that influence their diet and gut microbiota. In this cross-sectional purposive study, we evaluated the microbial community profiles of indigenous backyard poultry and their antimicrobial resistance genes (ARGs) using both cecal samples, which provide a more accurate representation of the core gut microbiota, and fecal samples, which allow for noninvasive monitoring and pathogen screening. We analyzed 32 pooled fecal and cecal samples using shotgun metagenomics, followed by functional and antimicrobial resistance (AMR) analyses to identify genes and metabolic pathways associated with poultry gut health and production. We report the presence of many commensal microorganisms in indigenous backyard poultry, with the most abundant being Bacteroidetes, Firmicutes, and Proteobacteria. The most dominant genera in the feces were Bacteroides, Methanobrevibacter, and Phocaeicola, while Bacteroides, Methanobrevibacter, and Chlamydia dominated in the ceca. No marked differences in microbial diversity were observed between the fecal and cecal samples. KEGG and COG database analyses revealed significantly enriched pathways associated with metabolism, cellular processes, and information storage and processing. Genes that confer resistance to tetracycline were the most abundant, raising concerns about the risks associated with inappropriate and excessive use of this antibiotic in poultry treatment. These findings deepen our understanding of the poultry gut microbiome, particularly regarding indigenous backyard poultry. Furthermore, the information about ARGs is a valuable indicator of antimicrobial use by rural smallholder farmers who have adopted the free-range production system in Kenya and other developing countries. These insights are crucial for farmers and the national livestock sector to monitor AMR in poultry, thereby enabling improved poultry management practices and informed policy decisions.

Enterococcus faecalis is an opportunistic pathogen of growing concern in both human and veterinary medicine due to its virulence traits, biofilm-forming ability, and resistance to multiple antibiotics. This study was aimed at investigating the occurrence, virulence factors, biofilm formation, and antimicrobial resistance (AMR) of E. faecalis in layer parent stock birds in Bangladesh. Samples (n = 80) were collected from healthy (cloacal swabs, n = 60) and dead (liver tissues, n = 20) birds. PCR was used for E. faecalis confirmation and detection of virulence genes. Biofilm formation was assessed using Congo red agar, and antimicrobial susceptibility was determined by disc diffusion. E. faecalis was detected in 76.3% of samples, with higher detection in live birds (80%) than in dead birds (65%). Biofilm production was found in 75.4% of isolates, with a higher rate in dead birds (84.6%) than live birds (72.9%). Strong and intermediate biofilm-forming capacities were more prevalent in isolates from dead birds. All eight tested virulence genes were commonly distributed, particularly pil (95.8%), ace (93.4%), and agg (91.8%), with no significant differences between live and dead bird isolates. High resistance was observed against ampicillin (93.4%), ciprofloxacin (80.3%), erythromycin (78.7%), and tetracycline (72.1%). Multidrug resistance (MDR) was found in 79.2% of isolates from live birds and 69.2% from dead birds, with multiple antibiotic resistance indices ranging from 0.27 to 0.72. To the best of our knowledge, this is the first study in Bangladesh determining MDR and virulence determinants in E. faecalis isolates from layer parent stock. These findings highlight E. faecalis as a prevalent, multidrug-resistant, and virulent bacterium in breeder flocks, emphasizing the need for routine AMR monitoring in parent stock farms.

The increasing use of polylactic acid (PLA) for single-use packaging has led to a growing accumulation of bioplastic waste. This study presents a comprehensive approach for enhancing the degradation of postconsumer PLA packaging waste, beginning with the isolation, screening, and identification of highly effective bacteria and culminating in the statistical optimization of their specific nutritional requirements. From compost samples, two highly effective strains were identified as Bacillus sp. SNRUSAC1 and Priestia aryabhattai SNRUSAC3 based on morphological, biochemical, and 16S rDNA sequence analyses. Notably, this is the first report of PLA degradation by the species P. aryabhattai. Initially, these strains achieved approximately 13% PLA dry weight loss after 56 days. To enhance their efficiency, a statistical optimization of nutritional components was performed. Under the optimized conditions, the degradation efficiency was dramatically enhanced, with SNRUSAC1 and SNRUSAC3 achieving 62.06% and 57.61% dry weight loss, respectively, in only 30 days. This represents over a fourfold increase in degradation in approximately half the time. This optimization also revealed novel, strain-specific requirements, with ferrous sulfate identified as a critical factor that had not been previously reported to influence the growth and degradative activity of P. aryabhattai. These findings establish Bacillus sp. SNRUSAC1 and P. aryabhattai SNRUSAC3 as novel, highly efficient candidates for the biodegradation of PLA plastic waste.