Microorganisms最新文献

NupR is a nucleoside permease regulator belonging to the GntR family, mainly regulating nucleoside transport in Bacillus thuringiensis. A conserved binding site for NupR was found in the promoter region of plcR. This study aimed to investigate the regulation of the virulence regulator PlcR by NupR and its impact on Bt virulence. We demonstrated that NupR can directly repress the expression of plcR. The expression of plcR can be induced by glucose and nucleosides. Glucose impacts the expression of plcR mainly through Spo0A, while the induction effect of nucleosides may be due to the production of ribose through nucleoside catabolism. In addition, NupR regulates the expression of the PlcR regulon, including hemolysin, phospholipase C, papR, and oligopeptide permease, which could result in the culture supernatant of BMB171 being less virulent to sf9 cells compared to the nupR knockout strain. The results combine the nutritional status of cells with virulence to form a regulatory loop, providing new ideas and research foundations for the study of bacterial virulence.

The aim of this study was to evaluate the usefulness of IgM anti-Tick-Borne Encephalitis (anti-TBE) intrathecal synthesis in the diagnosis and prediction of the clinical course of the disease. Thirty-six patients were included in the study (patients reported symptoms such as fever, headache, fatigue, and nausea/vomiting). CRP, White Blood Cells (WBC), pleocytosis, Cerebrospinal Fluid (CSF) protein concentration, CSF albumin concentration, serum IgM, serum IgG, CSF IgM, CSF IgG, IgM Index, IgG Index, and IgG Index/IgM Index ratio were the parameters which were examined in the individuals. An analysis of correlation presented statistical significance between IgM Index and pleocytosis and protein concentration in CSF in the whole group of individuals. IgM Index and IgG Index/IgM Index ratio may be used in the prediction of severity of TBE. The most probable link between the IgM intrathecal production and severity of TBE may be a result of delayed seroconversion to IgG, and therefore not an adequate response to the virus presence.

As transitional ecosystems between land and sea, estuaries are characterized by a unique environment that supports complex and diverse microbial communities. A comprehensive analysis of microbial diversity and ecological processes at different trophic levels is crucial for understanding the ecological functions of estuarine ecosystems. In this study, we systematically analyzed the diversity patterns, community assembly, and environmental adaptability of bacterial and protist communities using high-throughput sequencing techniques. The results revealed a higher alpha diversity for the bacteria than for protists, and the beta diversity pattern was dominated by species turnover in both communities. In addition, the two community assemblages were shown to be dominated by deterministic and stochastic processes, respectively. Furthermore, our results emphasized the influence of the local species pool on microbial communities and the fact that, at larger scales, geographic factors played a more significant role than environmental factors in driving microbial community variation. The study also revealed differences in environmental adaptability among different microbial types. Bacteria exhibited strong adaptability to salinity, while protists demonstrated greater resilience to variations in dissolved oxygen, nitrate, and ammonium concentrations. These results suggested differences in environmental adaptation strategies among microorganisms at different trophic levels, with bacteria demonstrating a more pronounced environmental filtering effect.

The challenges of antimicrobial resistance (AMR) to human health have pushed for the discovery of a new antibiotics agent from natural products. Cyanobacteria are oxygen-producing photosynthetic prokaryotes found in a variety of water habitats. Secondary metabolites are produced by cyanobacteria to survive extreme environmental stress factors, including microbial competition. This study presents the antibacterial activity and mechanism of the crude extracts from Cylindrospermum alatosporum NR125682 (A) and Loriellopsis cavernicola NR117881 (B) isolated from freshwater. The cyanobacteria were identified through 16S rRNA sequencing. Crude extracts were sequentially prepared using hexane, dichloromethane, and ethanol consistently. The minimum inhibition concentration (MIC), minimum bactericidal concentration (MBC) using the CSLI microdilution test protocol, and crude extract potential to inhibit the growth of the tested clinical bacteria strains were evaluated. The mechanism of action of the extracts including membrane damage, efflux pump, β-lactamase activity, DNA degradation, and extract-drug interaction was investigated using standard procedures. The hexane extract of B performed the best with a MIC (0.7-1.41 mg/mL) and MBC (1.41-2.81 mg/mL) range. All the crude extracts inhibited efflux pump activity against the bacteria tested. However, the extracts poorly inhibited β-lactamase. The ethanol extract of B exhibited the most appreciable antibacterial activity. The dichloromethane extract of B showed the highest significant DNA degradation potential, when compared with other samples. The extracts exhibited synergism when combined with erythromycin against some test bacteria, indicating primary microbial activity through membrane interactions. Hence, this study demonstrates the significance of cyanobacteria for antibiotic development.

Alfalfa (Medicago sativa L.) is an outstanding species used for the remediation of heavy metal-contaminated soil, and our previous research has shown that PGPR can promote plant growth under high-concentration lead stress. This discovery has forced scientists to search for PGPR strains compatible with alfalfa to develop an innovative bioremediation strategy for the remediation of lead-contaminated soil. This study used lead-tolerant rhizosphere soil of red clover as experimental material; cultured, isolated, and screened 52 excellent lead-tolerant bacteria that promote rhizosphere growth; and then inoculated them into alfalfa. Marked differences existed in the secretion of auxin, protease, and ACC deaminase among these strains. The results indicated that Pseudomonas spp. (strain Y2), Pseudomonas spp. (strain Y22), and Bacillus spp. (strain Y23) exhibited a strong growth-promoting ability in alfalfa, and there was no antagonistic reaction among the three strains, enabling their coexistence. The pot experiment manifested that strains Y2, Y22, Y23, and YH (a mixture of Y2, Y22, and Y23) could increase the plant height, root length, fresh and dry weight above ground, and fresh and dry weight below ground of alfalfa. They could all significantly raise the chlorophyll content and antioxidant enzyme activity in alfalfa (p < 0.05) and the content of malondialdehyde (MDA) in alfalfa. Furthermore, the concurrent inoculation of three distinct types of plant growth-promoting rhizobacteria (PGPR) significantly diminished lead (Pb) concentrations in rhizosphere soil, enhanced the levels of available potassium (AK) and available phosphorus (AP), and augmented the capacity of plants to absorb Pb. The results imply that PGPR can be employed to facilitate plant growth and microbial-assisted remediation of lead and other heavy metal-contaminated soil and establish a basis for further research on the growth-promoting mechanism of PGPR in plants.

Escherichia coli (E. coli) is one of the most common pathogens in both humans and livestock. This study aimed to investigate the prevalence of E. coli isolated from raw cow milk and evaluate its antimicrobial resistance rates. A total of 1696 milk samples were collected from Romanian dairy farms from 2018 to 2022. E. coli was isolated on various selective agar media, such as Cled agar and Columbia Agar with 5% Sheep Blood. The identification of E. coli was performed by MALDI-TOF MS. E. coli isolates were tested for their susceptibility against 18 commonly used antibiotics in a disk diffusion method. The overall prevalence of E. coli was 22.45% of all isolated pathogens. Antibiogram analysis revealed that 27.51% of E. coli isolates from milk were multidrug-resistant. Resistance was highest for penicillin-novobiocin (87.78%), followed by streptomycin (53.7%). Resistance to six drugs (amoxicillin, streptomycin, kanamycin-cephalexin, marbofloxacin, ampicillin) showed a significant increasing trend over time, while for two drugs (penicillin G-framycetin, doxycycline), a significant decrease was observed. Our results suggest that milk can be a reservoir of bacteria with the potential for infection in humans via the food chain. Furthermore, there is a need for surveillance and monitoring to control the increase in resistance to currently used antimicrobials in dairy farms because the occurrence of multidrug-resistant E. coli isolated from milk poses a health hazard to consumers.

Background: Despite kidney transplantation being a life-saving procedure, patients experience a high risk of developing fungal infections (FIs), with an increased risk of both morbidity and mortality, especially during the first year after transplant.

Methods: We herein conducted a narrative review of the most common FIs in kidney transplant recipients (KTRs), with a focus on prevalence, risk factors, mortality, and prevention strategies.

Results: The most common fungal pathogens in KTRs include Candida species (up to 70% of the overall FIs), Aspergillus species, Pneumocystis jiroveci, and Cryptococcus species. Fungal colonization, diabetes mellitus, chronic liver disease, malnutrition, and pre-existing lung conditions should all be acknowledged as possible predisposing risk factors. The mortality rate can vary from 25 to 50% and according to different settings and the types of FIs. Preventive strategies are critical for reducing the incidence of FIs in this population. These include antifungal prophylaxis, environmental precautions, and infection control measures. The use of novel tools (such as PCR-based molecular assays and NGS) for rapid and accurate diagnosis may play an important role.

Conclusions: Early recognition, the appropriate use of antifungal therapy, and preventive strategies are essential for improving graft loss and fatal outcomes in this vulnerable population. Future research is needed to optimize diagnostic tools, identify novel antifungal agents, and develop better prophylactic strategies for high-risk transplant recipients.

Campylobacter is one of the leading bacterial causes of gastroenteritis worldwide. It frequently contaminates poultry and other raw meat products, which are the primary sources of Campylobacter infections in humans. Plasmids, known as important mobile genetic elements, often carry genes for antibiotic resistance, virulence, and self-mobilization. They serve as the main vectors for transferring genetic material and spreading resistance and virulence among bacteria. In this study, we identified 34 new plasmids from 43 C. jejuni and C. coli strains isolated from retail meat using long-read and short-read genome sequencing. Pangenomic analysis of the plasmid assemblies and reference plasmids from GenBank revealed five distinct groups, namely, pTet, pVir, mega plasmids (>80 kb), mid plasmids (~30 kb), and small plasmids (<6 kb). Pangenomic analysis identified the core and accessory genes in each group, indicating a high degree of genetic similarity within groups and substantial diversity between the groups. The pTet plasmids were linked to tetracycline resistance phenotypes in host strains. The mega plasmids carry multiple genes (e.g., aph(3')-III, type IV and VI secretion systems, and type II toxin-antitoxin systems) important for plasmid mobilization, virulence, antibiotic resistance, and the persistence of Campylobacter. Together, the identification and comprehensive genetic characterization of new plasmids from Campylobacter food isolates contributes to understanding the mechanisms of gene transfer, particularly the spread of genetic determinants of virulence and antibiotic resistance in this important pathogen.

Phenolic compounds are industrially versatile chemicals that have been successfully produced in microbial cell factories. Unfortunately, most phenolic compounds are highly toxic to cells in specific cellular environments or above a particular concentration because they form a complex with iron and promote hydroxyl radical production in Fenton reactions, resulting in the ferroptosis of cells. Here, we demonstrated that overexpression of efflux pumps and porins, including porins LamB and OmpN, and efflux pumps EmrAB, MdtABC, and SrpB, can enhance Escherichia coli phloroglucinol (PG) tolerance by inhibiting the generation of hydroxyl radicals. In addition, LamB and OmpN overexpression improved the bioproduction of PG. Furthermore, efflux pumps and porins can enhance bacterial tolerance to various phenolic compounds, including phenol, catechol, resorcinol, pyrogallol, and 2-naphthol. LamB and MdtABC confer a generalized tolerance to phenols. However, EmrAB, OmpN, and SrpB showed inconsistent effects of bacterial tolerance to different phenolic compounds. Our results will theoretically support the construction of phenolic compound-tolerant bacteria strains, which should be more efficient in the biosynthesis of phenols.

Classical preoperative skin antisepsis is insufficient in completely eliminating bacterial skin colonization for arthroplasty. In contrast, photodynamic therapy (PDT) with red light and methyl-aminolevulinate (MAL), combined with skin antisepsis, led to the absence of bacterial growth in healthy participants, though with local skin erythema, posing an obstacle for orthopedic surgery. Therefore, we explored whether artificial daylight PDT (PDT-DL) was superior to red light. Twenty healthy participants were allocated to either 5-aminolevulinic acid-(5-ALA) PDT-DL (n = 10) or MAL-PDT-DL (n = 10) before antisepsis with povidone-iodine/alcohol. Skin swabs from the groin were taken to cultivate bacteria at baseline, after PDT-DL, and after the subsequent antisepsis. Additional swabs were taken on day 4 before and after antisepsis without PDT. The contralateral groin of each participant and of ten additional healthy volunteers served as the control (n = 30). In selected participants, 16S rRNA-based amplicon deep sequencing was performed. All participants showed a baseline bacterial colonization. After a PDT-DL with skin antisepsis, bacterial growth occurred in three (30%) and in one (10%) participants with 5-ALA and MAL, respectively, compared to the sixteen (55%) participants in the control group. On day 4, three (30%) participants per group showed positive cultures post antisepsis. Adverse effects were reported in six (60%) and zero (0%) participants for 5-ALA- and MAL-PDT-DL, respectively. The skin bacteriome changes correlated with the bacterial culture results. The MAL-PDT-DL with skin antisepsis significantly increased bacterial reduction on the skin without adverse effects. This offers an opportunity to prevent infections in arthroplasty patients and reduce antibiotic use, thus contributing to antibiotic stewardship goals emphasized in the One Health approach.