MicrobiologyOpen最新文献

Spores of a hot spring isolated strain of Bacillus subtilis were tested as a biotechnological tool to be used for the detoxification and bioremedition of heavy metals. Lead and cadmium were efficiently adsorbed by B. subtilis spores with those of C1 more efficient than those of the lab collection strain PY79. Metal-adsorption did not alter the functionality of C1 spores that were still fully resistant to heat, ethanol or chloroform and able to germinate after the interaction with Cd²⁺ or Pb²⁺. The spore-adsorbed metals were released upon disruption of the spore coat layers, suggesting that the metals were mostly accumulated within the spore coat. Heat-inactivated spores released almost all adsorbed metals, allowing the recovery of Cd²⁺ and Pb²⁺. While Cd²⁺ polluted water impaired the normal germination and growth of seeds of the model plant Arabidopsis thaliana, treatment of the polluted water with C1 spores restored plant growth.

Gut microbes are closely related to host immunity and health, and mice are frequently used as a common model organism in biomedicine to study various diseases. Numerous studies based on mouse gut microbes have been conducted, but whether there are differences in the gut microbial profiles of healthy mice of different strains has not been revealed. In this study, we performed a meta-analysis comparing four strains (inbred strains: C57BL and BALB; outbred strains: KM and ICR) of mouse healthy gut microbial 16S V3-V4 data based on publicly available online data. We focused on microbial diversity, microbial composition, abundance differential microbiota, and co-abundance networks. We found that the gut microbes of these four strains of mice differed in the above metrics to varying degrees. Our study found significant differences in gut microbiology among four strains of healthy mice. The strain will be a background factor that cannot be ignored in future studies of gut microbiology in mice. The impact of this factor on gut microbiology experiments should be considered.

Respiratory aspergillosis refers to a range of infections, from allergic to chronic and invasive, which can be life-threatening and are primarily caused by Aspergillus fumigatus and Aspergillus flavus. Other species, including Aspergillus terreus, Aspergillus nidulans, and Aspergillus versicolor, have also been implicated in respiratory infections. Treatment for chronic to invasive pulmonary aspergillosis typically involves azole antifungal drugs, although studies have shown varying minimum inhibitory concentrations (MIC) for these medications, with a growing concern over voriconazole resistance. During the period from August 2022 to May 2024, characteristic hyphae were detected in 7.2% of lower respiratory samples, with culture positivity in 12.8%, including early morning sputum and bronchoalveolar lavage fluid samples. A. flavus (n = 282) was the most frequently isolated species, followed by A. fumigatus (n = 86). Additionally, a seasonal trend was observed for Aspergillus infections, with peaks in April and September. The MIC of itraconazole, voriconazole, posaconazole, amphotericin B, ravuconazole, and caspofungin were assessed for the isolated Aspergillus species. A higher MIC of amphotericin B was observed against A. flavus and A. terreus, whereas azoles exhibited a relatively lower MIC. Caspofungin and posaconazole exhibited the lowest MIC against the isolated Aspergillus species. Therefore, it is crucial to identify the causative fungi and determine the antifungal MIC for Aspergillus species responsible for lower respiratory tract infections. This study emphasizes the significance of respiratory aspergillosis in TB-endemic regions of Eastern India.

Malaria is a life-threatening disease caused by Plasmodium, transmitted through the bites of infected female Anopheles mosquitoes. Despite global efforts, malaria remains a major health burden in developing countries. In Tanzania, cultural beliefs and misconceptions often delay treatment, especially in rural areas. This article aims to evaluate the level of malaria knowledge among the Tanzanian population and identify demographic factors associated with disparities in awareness. This cross-sectional study used secondary data from the 2021–2022 Tanzania Demographic and Health Survey, analyzing responses from 18,747 individuals aged 15 years and older. Data on malaria-related knowledge, attitudes, and practices were collected through standardized questionnaires. Malaria knowledge varied significantly by age, gender, education, and location (p < 0.05). Awareness was highest among individuals aged 20–24 and lowest among those over 50. Urban residents had greater knowledge than their rural counterparts. Education was strongly linked to awareness, with those having secondary or higher education scoring better. Male-headed households showed slightly higher knowledge levels. Media exposure and mobile phone ownership were also associated with increased malaria awareness. Bridging knowledge gaps through targeted education, digital tools, and improved rural health infrastructure is essential for effective malaria control in Tanzania.

Karst freshwater systems represent unique ecological niches where physicochemical and biological interactions promote intensive calcium carbonate precipitation and the formation of tufa barriers. Here, we studied the composition, diversity, and functional potential of prokaryotic and microeukaryotic communities involved in early-stage tufa formation at two sites within the Plitvice Lakes National Park, Croatia. Over a 5-day period in two different seasons, tufa and water samples were collected at Prošćansko Lake and Novakovića Brod to examine temporal and spatial microbial dynamics. High-throughput sequencing revealed early stabilization of prokaryotic communities within tufa biofilms, dominated by genera, such as Bacillus, Delftia, Hyphomicrobium, and Methylobacterium–Methylorubrum, which are linked to carbonate precipitation processes. With biofilm maturation, shifts toward Acinetobacter and Rhodoferax indicated increasing heterotrophic activity and organic matter degradation. In contrast, microeukaryotic communities were more variable, with diatoms and Zygnemophyceae contributing to extracellular polymeric substance production, crucial for carbonate entrapment. Site-specific patterns reflected environmental influences, such as hydrodynamics and terrestrial organic input. The results underscore the importance of microbial succession and community specialization in the formation and stability of tufa barriers, offering new insights into microbial contributions to biogeochemical processes in karst freshwater systems.

This study explores the potential of incorporating antimicrobial peptides (AMPs) into dental resin composites to enhance resistance against Streptococcus mutans, a key contributor to biofilm-related dental infections through its surface protein adhesins. A comprehensive computational approach was applied to evaluate AMP interactions. Molecular docking was used to assess AMP binding to dental resins, followed by docking the top AMP candidates to S. mutans adhesins. The resulting complexes underwent 100 ns molecular dynamics simulations, and binding affinities were refined using MM/PBSA free energy calculations. Several AMPs showed strong binding to dental resins and S. mutans adhesins. Pardaxin and tachystatin displayed high affinities for critical adhesion sites. MM/PBSA analysis confirmed strong binding, with tachystatin showing a ΔG of –62.03 kcal/mol, significantly better than the standard inhibitor C16G2 (ΔG = −33.34 kcal/mol), suggesting enhanced inhibitory potential. Dental composites incorporating specific AMPs show promise in targeting S. mutans adhesins and preventing biofilm formation. However, these results are based solely on computational modeling. Experimental validation is essential to confirm biological efficacy, optimize AMP integration into resin formulations, and evaluate safety for potential clinical applications.

Clonostachys rosea is a necrotrophic mycoparasite studied for biocontrol of plant pathogenic fungi, including Botrytis cinerea, the causal agent of gray mold that causes economic losses in several common fruits and vegetables. This study evaluated how the culture aeration, manipulated through the medium-to-flask volume ratio, affects the submerged production of conidia and microsclerotia, key propagules for disease control. A low medium-to-flask ratio (1:5), which enhances aeration, significantly increased propagule yields. A high C:N ratio (50:1) favored submerged conidia production under elevated aeration, while microsclerotia formed only with low C:N (10:1) and boosted under high aeration. These propagules, along with cell-free culture filtrates, were formulated into water-dispersible microgranules and tested for efficacy against gray mold on cherry tomatoes. All formulations reduced disease incidence. UPLC ESI–QTOF–MS analysis of the organic extract from the culture filtrate revealed sorbicillinoids as the major antifungal metabolites. Overall, this study highlights the role of aeration in optimizing C. rosea submerged cultivation and supports the potential of its propagules and metabolites for use in biocontrol strategies against postharvest disease induced by B. cinerea.

Asymptomatic rectal carriers are recognized as reservoirs of carbapenem-resistant Klebsiella pneumoniae (CRKp), which can spread epidemic high-risk clones [e.g., sequence types (ST)-307] and plasmids [incompatibility group (Inc)-X3] in hospitals, with possible transmission into the community. This study investigated the epidemiology and characteristics of CRKp high-risk clones ST307 among rectal carriage isolates from community hospitals. A carbapenemase positivity rate of 24% was observed for all rectal screening performed during hospital admission (February to August 2021) in Gauteng, South Africa; 252 CRKp isolates were characterized. Antimicrobial susceptibility was performed using the VITEK 2 automated system, and polymerase chain reaction assays were used to detect K. pneumoniae ST307, carbapenemase genes, and associated mobile genetic elements (MGEs e.g., IncX3, IS3000). Of the 252 isolates, 25% (64/252) were ST307 positive and 75% (188/252) were non-ST307. Among the 64 ST307, 45% (29/64) harbored bla_OXA-181 on IncX3 plasmids. Occurrence of bla_OXA-181 among ST307 (69%; 44/64) when compared to non-ST307 (48%; 91/188) was statistically significant (p-value = 0.002). Fourteen isolates, including two ST307, harbored double carbapenemase genes. Carbapenemase gene combinations include six bla_NDM+bla_OXA-48-like, four bla_NDM +bla_OXA-181, three bla_KPC+bla_OXA-181, and one bla_OXA-181+bla_VIM. One ST307 isolate harbored three carbapenemase genes (bla_NDM+bla_OXA-48+bla_OXA-181). Level of antimicrobial resistance was significantly (p-value < 0.001) associated with the occurrence of ST307, comprising 73% (47/64) extensively drug resistant. This study highlights the need for rectal screening of XDR clones and plasmids using simple and cost-effective genomic methodologies suitable for low- and middle-income countries for local risk management and control of infectious diseases in hospitals.

Listeria monocytogenes is a food-borne pathogen that continues to threaten food safety by persisting in food production environments (FPEs). Its tolerance to stressors introduced in FPEs is well characterized; however, the effect of the growth phase on stress response gene expression is less understood. Here, we utilize transcriptome sequencing to analyze gene expression of the persistent L. monocytogenes strain 6179 in response to 30-min exposure to either lactic acid or oxidative stress when grown to either logarithmic or stationary growth phase. Analysis of this data revealed distinct gene expression responses to stress exposure between the two growth phases. Exposure to lactic acid (1%, pH 3.4) resulted in 1809 significant (Q < 0.05, log₂fold changes with absolute values ≥ 1) differentially expressed (DE) genes in stationary phase cells and 175 significant DE genes in logarithmic growth phase cells. Upon oxidative stress exposure (15 mM hydrogen peroxide), 184 significant DE genes were observed in the stationary phase and 819 significant DE genes in the logarithmic phase. Interestingly, in the logarithmic growth phase, 37 of the 50 most upregulated genes were shared between responses to acid and oxidative stress; these included genes involved in cysteine transport. In contrast, stationary phase cell gene expression was more influenced by the type of stress exposure, and the majority of upregulated genes were members of the σ^B regulon. Collectively, these results provide further insight into the impact of growth phase on gene expression in L. monocytogenes in response to lactic acid and hydrogen peroxide stress exposure.

Lactococcosis is a major bacterial disease impacting rainbow trout production in South Africa and Southeast Asia, particularly during summer. In this study, 15 isolates from affected aquaculture facilities were characterised, revealing Lactococcus petauri (n = 12) as the predominant species, rather than the traditionally recognised L. garvieae (n = 3). This indicates a potential shift in the aetiology of lactococcosis with implications for diagnosis and management. Genomic screening identified multiple virulence factors, including adhesins in 14 isolates, capsular polysaccharide biosynthesis genes in 12, and sortase-anchored proteins in all isolates, highlighting strain-specific differences in pathogenic potential. Antimicrobial resistance (AMR) profiling revealed ermB (n = 10) and tetS (n = 11), consistent with resistance to macrolides and tetracyclines commonly applied in aquaculture. Phenotypic susceptibility testing against eight antimicrobial agents showed uniform resistance to nalidixic acid (15/15 isolates), alongside resistance to trimethoprim (12/15), sulfamethoxazole (11/15), and ciprofloxacin and oxacillin (7/15 each). These phenotypic results, while not fully aligned with the ARG profile, reflect aquaculture-relevant antimicrobial exposures and indicate the presence of both intrinsic and acquired resistance mechanisms. Most (13/15) isolates contained 1–3 prophage regions, although none of these harboured any known virulence or AMR genes. However, they did genes encoding phage defence such as AbiD and R-M systems. This information is important when considering the potential development of phage therapy to control piscine disease. Together, these findings advance understanding of the epidemiology, pathogenicity, and resistance dynamics of Lactococcus species in aquaculture and underscore the need for sustainable strategies to mitigate lactococcosis outbreaks.