MicrobiologyOpen最新文献

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.

The escalating plastics crisis, exacerbated by the accumulation of nonbiodegradable polyesters in the environment, has necessitated the exploration of sustainable waste management solutions such as enzymatic hydrolysis in industrial recycling. So far, the focus of these efforts has been on cutinase-related polyethylene terephthalate (PET) degrading carboxylesterases, or PETases. In this work, we report the discovery and initial activity screen of previously uncharacterized, thermostable enzymes with polyesterase activity through comprehensive phylogenetic and sequence analysis of a bacterial family of esterases, Lipase Family 1.5. These enzymes are related to the previously identified polybutylene succinate co-terephthalate (PBAT) degrading carboxylesterases Cl_EstA and Cl_EstB from Clostridium botulinum and PfL1 from Pelosinus fermentans. Originating from thermophilic bacteria, we show that these enzymes can be expressed heterologously in Escherichia coli and degrade the polyesters PBAT and polybutylene succinate co-butylene adipate (PBSA), though they exhibit limited activity against PET. Notably, our results show that these enzymes are more effective at degrading the fully aliphatic polyester PBSA compared to the aliphatic-aromatic co-polyester PBAT, with three members of this enzyme family achieving complete solubilization of 5 mg/mL milled PBSA within 2 days at a low enzyme concentration (100 nM). This study highlights the substantial opportunity to find novel enzymes from nature that possess the required thermal stability for industrial applications, potentially reducing the need for extensive protein engineering.

Gut microbiota is linked with health, including obesity, in the general population. It is unknown whether adiposity at postpartum is influenced by gut microbiota already during pregnancy. We investigated the association between the gut microbiota's composition and predicted function by metagenomics during pregnancy and the women's adiposity (body mass index [BMI], waist-to-hip ratio [WHR], body fat%) assessed at 1-, 2-, and 5–6-years' postpartum in 257 women with overweight or obesity based on prepregnancy BMI values. Body fat% at 1-year, but not at 2- or 5–6-years' postpartum, was associated inversely with α-diversity during pregnancy. Bacterial species GGB3034 SGB4030 (family Erysipelotrichaceae) was higher in women with normal weight than those in women with obesity at 1-year postpartum (q = 0.02), other species being borderline statistically significant (q < 0.25). High WHR and body fat% at 1-year postpartum were associated with two species (q < 0.25). Considering predicted functions of bacteria, an association was detected for BMI, WHR, and body fat%, e.g., body fat% and glycogen biosynthesis I (q < 0.25). Gut microbiota during pregnancy predicted the BMI and body fat% at 1-year postpartum (ROC > 0.50, p < 0.02). Postpartum adiposity was associated with several species and α-diversity. Gut microbiota during pregnancy may be involved in the persistence of obesity and its comorbidities after pregnancy.

Antibiotic resistance is a global menace, particularly in low- and middle-income countries where antimicrobial resistance (AMR) in zoonotic pathogens like Salmonella is on the rise. This study investigates the phenotypic and genotypic AMR in Salmonella enterica. isolated from cattle faeces collected by faecal grab method on a Nigerian dairy farm. Salmonella enterica was cultured from the faecal samples of 138 individual cattle at the University of Ibadan dairy farm, with identification done through MALDI-TOF-MS, genus-specific PCR, and Microbact 24E. The minimum inhibitory concentration (MIC) of selected antibiotics was determined by Vitek 2 compact system. Whole genome sequencing was conducted on eighteen isolates that met pre-sequencing quality standards, utilizing the Illumina HiSeq platform. Sequence types and AMR genes were determined using publicly available tools. Interestingly, all isolates showed 100% phenotypic susceptibility to the tested antibiotics. Notably, several rare Salmonella enterica serovars were identified among the sequenced strains; Koketime (n = 2), Hadar (n = 3), Banalia|Tounouma (n = 10), Hermannswerder (n = 2), and Chomedey|Glostrup (n = 1). While most of the sequenced Salmonella enterica strains (15 out of 18) lacked AMR genes besides efflux transporter gene, a strain of Chomedey|Glostrup serovar exhibited genes associated with reduced susceptibility to aminoglycosides (aph(3′)-lb, aph(6)-Id), quinolones (qnrB), sulphonamides (sul2), and tetracycline (tet(A)), while Koketime strains possessed fosfomycin resistance genes (fosA7) besides the efflux genes. The absence of phenotypic and genotypic AMR in most of the isolates highlights the possibility that AMR could be controlled in livestocks in developing countries.

Enterococcus faecalis (E. faecalis) is a notable public health bacterium since it can thrive on high-touch surfaces in restaurants. This study aimed to isolate E. faecalis, conduct antibiogram to determine resistance patterns, explore the virulence profile and observe biofilm-forming properties. A total of 90 samples were collected from BAU restaurants, including high-touch surfaces and popular food items. Initial isolation employed culture-based method followed by Gram's staining technique and biochemical tests. Molecular confirmation was achieved via polymerase chain reaction (PCR) targeting the ddl_{E. faecalis} gene specific for E. faecalis. Antibiogram was performed using the Disc Diffusion Test for commonly used antibiotics. Genotypic detection of antibiotic resistance and virulence profile were also explored by PCR. Lastly, the Congo Red (CR) test was done to examine the biofilm-forming isolates. Results indicated a prevalence (30%) of E. faecalis in both food and surface samples, with higher contamination rates in crowded areas. Antibiogram revealed high resistance to Penicillin (100%) and moderate to low resistance towards Tetracycline, Ciprofloxacin, Erythromycin and Chloramphenicol. Shockingly, bla_TEM gene was found in 81.48% of isolates, and 18.51% were detected as multidrug-resistant. We found a very high prevalence of the virulence genes fsrA, fsrB, fsrC, gelE, pil, agg, and ace. Finally, the CR test revealed 33.33% and 44.44% isolates as strong and intermediate biofilm formers respectively. This study reinforces the significance of routine surveillance in combating the spread of antimicrobial resistance through the food chain and the prospective use of E. faecalis as a contamination marker.

Antimicrobial-resistant and virulent Staphylococcus aureus strains are spreading across diverse environments and hosts, but studies on Brazilian wildlife remain limited. From April to December 2021, oropharyngeal swabs were collected from 197 wild birds spanning five orders, 25 families, and 54 species in São Camilo State Park, a protected Atlantic Forest fragment facing significant pressure from surrounding agricultural landscapes. S. aureus was detected in 12.2% of the birds, including 27 methicillin-susceptible S. aureus (MSSA) and two Methicillin-resistant (MRSA) isolates. MSSA strains showed high inducible Macrolide-Lincosamide-Streptogramin B (MLSB) resistance, with 37% carrying the blaZ gene for penicillin resistance, and antimicrobial-resistant isolates frequently harboring the scn gene. Genomic sequencing identified both MRSA strains as ST398, marking the first report of MRSA ST398 in Brazilian wildlife. These strains displayed a broad resistome, including genes for resistance to multiple antimicrobial classes, as well as a comprehensive virulome, although in vivo assays with Galleria mellonella suggested low virulence. Phylogenomic analysis clustered the MRSA strains with MSSA from swine in northeastern Brazil, suggesting that these strains likely originated in livestock, acquired the SCCmec element, and spread into natural ecosystems. These findings suggest a possible spillover of livestock-associated antimicrobial-resistant S. aureus into a protected forest fragment, highlighting the potential for anthropogenic microbial threats to reach wildlife and underscoring the importance of including wild species in antimicrobial resistance surveillance, especially in fragmented ecosystems increasingly exposed to human activities.