Microorganisms最新文献

The intensified concerns related to agrochemicals' ecological and health risks have encouraged the exploration of microbial agents as eco-friendly alternatives. Some members of Bacillus spp. are potential plant-growth-promoting agents and benefit numerous crop plants globally. This study aimed to explore the beneficial effects of two Bacillus strains (B. subtilis strain IS1 and B. amyloliquificiens strain IS6) capable of alleviating the growth of tomato plants against salinity stress and Fusarium wilt disease. These strains were able to significantly promote the growth of tomato plants and biomass accumulation in pot trials in the absence of any stress. Under salinity stress conditions (150 mM NaCl), B. subtilis strain IS1 demonstrated superior performance and significantly increased shoot length (45.74%), root length (101.39%), fresh biomass (62.17%), and dry biomass (49.69%) contents compared to control plants. Similarly, B. subtilis strain IS1 (63.7%) and B. amyloliquificiens strain IS6 (32.1%) effectively suppressed Fusarium wilt disease and significantly increased plant growth indices compared to the pathogen control. Furthermore, these strains increased the production of chlorophyll, carotenoid, and total phenolic contents. They significantly affected the activities of enzymes involved in antioxidant machinery and the phenylpropanoid pathway. Hence, this study effectively demonstrates that these Bacillus strains can effectively alleviate the growth of tomato plants under multiple stress conditions and can be used to develop bio-based formulations for use in the fields.

There is increasing adoption of winter cover crops (WCCs) in corn and soybean production in Canada, primarily to reduce erosion and increase soil organic matter content. WCCs have the potential to influence nematode communities by increasing free-living nematodes and decreasing plant-parasitic nematodes or vice versa. However, the mechanism by which WCCs change nematode community assemblages still remains a key question in soil food web ecology. We tested the hypothesis that the long-term use of rye (Secale cereale), barley (Hordeum vulgare) and oat (Avena sativa) as monocultures or mixtures promotes nematode communities and improves overall soil health conditions compared to winter fallow. The results from this study revealed that the use of WCCs generally promoted a higher abundance and diversity of nematode communities, whereas plant parasitic nematodes were the most abundant in winter fallow. Moreover, the mixtures of WCCs had more similar nematode communities compared to rye alone and winter fallow. The structure and enrichment indices were higher with WCCs, indicating higher nutrient cycling and soil suppressiveness, which are signs of healthy soil conditions. Furthermore, WCCs significantly reduced the populations of root lesion nematode Pratylenchus, although their numbers recovered and increased during the main crop stages. Additionally, mixtures of WCCs promoted the highest abundance of the stunt nematode Tylenchorhynchus, whereas winter fallow had a higher abundance of the spiral nematode Helicotylenchus during the fallow period and the main crop stages. The results show that the long-term use of cover crops can have a positive impact on nematode communities and the soil food web, but these changes depend on the type of WCCs and how they are used.

Antimicrobial resistance is an increasing societal burden worldwide, with ESKAPEE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species and Escherichia coli) pathogens overwhelming the healthcare sectors and more recently becoming predominantly a concern for their persistence in food and food industries, including agricultural settings and animal husbandry environments. The aim of this review is to explore the mechanisms by which the ESKAPEE group gained its multidrug resistance profiles, to analyse their occurrence in different foods and other related reservoirs, including water, and to address the current challenges due to their spread within the food production chain. Moreover, the repertoire of surveillance programmes available focused on monitoring their occurrence, common reservoirs and the spread of antimicrobial resistance are described in this review paper. Evidence from the literature suggests that restricting our scope in relation to multidrug resistance in ESKAPEE pathogens to healthcare and healthcare-associated facilities might actually impede unveiling the actual issues these pathogens can exhibit, for example, in food and food-related reservoirs. Furthermore, this review addresses the need for increasing public campaigns aimed at addressing this challenge, which must be considered in our fight against antimicrobial resistance shown by the ESKAPEE group in food and food-related sectors.

The availability of fixed nitrogen limits overall agricultural crop production worldwide. The so-called modern "green revolution" catalyzed by the widespread application of nitrogenous fertilizer has propelled global population growth. It has led to imbalances in global biogeochemical nitrogen cycling, resulting in a "nitrogen problem" that is growing at a similar trajectory to the "carbon problem". As a result of the increasing imbalances in nitrogen cycling and additional environmental problems such as soil acidification, there is renewed and increasing interest in increasing the contributions of biological nitrogen fixation to reduce the inputs of nitrogenous fertilizers in agriculture. Interestingly, biological nitrogen fixation, or life's ability to convert atmospheric dinitrogen to ammonia, is restricted to microbial life and not associated with any known eukaryotes. It is not clear why plants never evolved the ability to fix nitrogen and rather form associations with nitrogen-fixing microorganisms. Perhaps it is because of the large energy demand of the process, the oxygen sensitivity of the enzymatic apparatus, or simply failure to encounter the appropriate selective pressure. Whatever the reason, it is clear that this ability of crop plants, especially cereals, would transform modern agriculture once again. Successfully engineering plants will require creating an oxygen-free niche that can supply ample energy in a tightly regulated manner to minimize energy waste and ensure the ammonia produced is assimilated. Nitrogen-fixing aerobic bacteria can perhaps provide a blueprint for engineering nitrogen-fixing plants. This short review discusses the key features of robust nitrogen fixation in the model nitrogen-fixing aerobe, gamma proteobacteria Azotobacter vinelandii, in the context of the basic requirements for engineering nitrogen-fixing plants.

Background:Providencia is a G ram-negative bacillus that most frequently colonizes the urinary tract and is often resistant to many antimicrobials. This study aimed to evaluate the resistance patterns of Providencia spp. and clinical outcomes due to the paucity of data. Methods: A multi-center, descriptive, retrospective chart review of adult patients with Providencia spp. infections was conducted from 1 January 2020 to 31 May 2022. The primary outcome was to describe the drug resistance patterns of Providencia spp. isolates. This study's secondary outcome was to evaluate the clinical outcomes of patients with Providencia spp. infections. Results: Of the 312 patients screened, 244 were excluded primarily for polymicrobial infections. The mean age was 70 years, and 39 (56.5%) were males. Of the 68 included cases, 46 (67.6%) were P. stuartii, 20 (29.4%) were P. rettgeri, and 2 (2.9%) were P. alcalifaciens. The most common infections were bacteremia 38 (55.8%), followed by 27 (39.7%) urinary tract infections and 3 (4.4%) wound infections. In this study, 45 patients (65.2%) had urinary catheters. The primary antibiotics used for treatment consisted of ceftriaxone (25 (36.2%)), cefepime (20 (29%)), and meropenem (10 (14.5%)). Only 5 of 68 (7.2%) cases were multidrug- resistant and required meropenem. In total, 19 patients (27.1%) died during their admission, but none were related to Providencia infections. A total of 10 of the 68 patients (14.5%) were readmitted within 30 days for reasons unrelated to the progression or recurrence of Providencia infections. Conclusions:Providencia bacteremia is predominantly seen in elderly patients. Third- generation cephalosporins remain an appropriate choice of antibiotics for Providencia spp. Providencia stuartii was the only species with multidrug resistance.

In this study, silver nanoparticles (AgNPs) were synthesized using a green method from an extract of the edible insect Oxya chinensis sinuosa (O_extract). The formation of AgNPs (O_AgNPs) was confirmed via UV-vis spectroscopy, and their stability was assessed using Turbiscan analysis. The size and morphology of the synthesized particles were characterized using transmission electron microscopy and field-emission scanning electron microscopy. Dynamic light scattering and zeta potential analyses further confirmed the size distribution and dispersion stability of the particles. The average particle size was 111.8 ± 1.5 nm, indicating relatively high stability. The synthesized O_AgNPs were further characterized using X-ray photoelectron spectroscopy (XPS), high-resolution X-ray diffraction (HR-XRD), and Fourier transform infrared (FTIR) spectroscopy. XPS analysis confirmed the chemical composition of the O_AgNP surface, whereas HR-XRD confirmed its crystallinity. FTIR analysis suggested that the O_extract plays a crucial role in the synthesis process. The antibacterial activity of the O_AgNPs was demonstrated using a disk diffusion assay, which revealed effective activity against common foodborne pathogens, including Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, and Bacillus cereus. O_AgNPs exhibited clear antibacterial activity, with inhibition zones of 15.08 ± 0.45 mm for S. Typhimurium, 15.03 ± 0.15 mm for E. coli, 15.24 ± 0.66 mm for S. aureus, and 13.30 ± 0.16 mm for B. cereus. These findings suggest that the O_AgNPs synthesized from the O_extract have potential for use as antibacterial agents against foodborne bacteria.

Along with affecting oral health, oral microbial communities may also be endogenously translocated to the gut, thereby mediating the development of a range of malignancies in that habitat. While species-level studies have proven the capability of oral pathogens to migrate to the intestine, genetic evidence supporting this mechanism remains insufficient. In this study, we identified over 55,000 oral translocation genes (OTGs) associated with colorectal cancer (CRC) and inflammatory bowel disease (IBD). These genes are primarily involved in signal transduction and cell wall biosynthesis and show consistency in their functions between IBD and CRC. Furthermore, we found that Leclercia adecarboxylata, a newly discovered opportunistic pathogen, has a significantly high abundance in the gut microbiota of colorectal cancer patients. OTGs of this pathogen were enriched in 15 metabolic pathways, including those associated with amino acid and cofactor metabolism. These findings, for the first time, provide evidence at the genetic level of the transfer of oral pathogens to the intestine and offer new insights into the understanding of the roles of oral pathogens in the development of gastrointestinal cancers.

Background: Oral candidiasis has been documented in patients with SARS-CoV-2 infection, with varying prevalence rates across geographic regions and patient demographics. This study aimed to ascertain the incidence, characteristics, and risk factors associated with the development of oral candidiasis in patients hospitalized for SARS-CoV-2 infection in a tertiary infectious diseases hospital in Romania.

Methods: A retrospective analysis was conducted on adult patients hospitalized between March 2020 and December 2022 with moderate or severe forms of SARS-CoV-2 infection, for whom a culture of lingual scrapings for Candida spp. was performed.

Results: A total of 294 patients were deemed eligible for inclusion in the analysis, with an incidence rate of oral candidiasis of 17.0%. The incidence of oral candidiasis was 4.2 times higher in patients with severe forms of SARS-CoV-2 infection compared to those with moderate forms. Patients with a diagnosis of COVID-19 and oral candidiasis were more likely to receive antibiotics (98.0% vs. 86.1%, p = 0.017) and corticosteroids (100% vs. 83.6%, p = 0.003) than those without oral candidiasis. These findings were associated with a 19% higher relative risk of developing oral candidiasis for patients who received corticosteroid therapy compared to those who did not, and a 13% higher relative risk for those who were administered antibiotics compared to those who were not. The presence of respiratory insufficiency increased the odds of oral candidiasis association 4.7-fold (88.0% vs. 61.1%, p < 0.001).

Conclusions: Although the data have been analyzed retrospectively, we have shown that individuals with severe forms of COVID-19 exhibited an elevated risk of developing oral candidiasis. The administration of antibiotics and corticosteroids was identified as a positive predictor for the development of oral candidiasis. The data presented here suggest that a key aspect of the therapeutic management of patients with SARS-CoV-2 infection should include the implementation of preventive measures to minimize the risk of secondary fungal infections.

Bacterial resistance and persistence in food environments are major concerns for the industry, which constantly seeks new strategies to reduce microbial contamination. Rhamnolipids (RL) biosurfactants are considered sustainable and green alternatives to synthetics; furthermore, they have demonstrated potential for controlling various foodborne pathogens. Food environments are typically exposed to diverse pH, solutes, temperatures, and water activity (a_w) levels that may favor the survival of pathogens. Therefore, it is crucial to consider these factors in evaluating the performance of novel antimicrobials. Our study examined the influence of pH and sucrose on the antimicrobial activity of RL against both planktonic and biofilm of Listeria monocytogenes. We found that the presence of sucrose can enhance the antimicrobial effectiveness of RL against both planktonic and sessile bacteria. The addition of sugar particularly improved RL action at pH 6 and 7. Moreover, we observed that the type and size of RL self-assembly structures depend on the pH and sucrose concentration. These findings suggest potential for developing RL-based innovative methods to control L. monocytogenes in sugar-rich or -low a_w foods and environments.

West Nile virus (WNV) is a mosquito-borne pathogen with a worldwide distribution. Climate change and human activities have driven the expansion of WNV into new territories in Europe during the last two decades. Romania is endemic for WNV circulation since at least 1996 when the presence of lineage 1 was documented during an unprecedented outbreak. Lineage 2 was first identified in this country during a second significant human outbreak in 2010. Its continuous circulation is marked by clade replacement, and even co-circulation of different strains of the same clade was observed until 2016. The present study aims to fill the information gap regarding the WNV strains that were circulating in Romania between 2017 and 2023, providing chiefly viral sequences obtained from mosquito samples collected in the Bucharest metropolitan area, complemented by human and bird viral sequences. WNV was detected mainly in Culex pipiens mosquitoes, the vectors of this virus in the region, but also in the invasive Aedes albopictus mosquito species. Lineage 2 WNV was identified in mosquito samples collected between 2017 and 2023, as well as in human sera from patients in southern and central Romania during the outbreaks of 2017 and 2018. Both 2a and 2b sub-lineages were identified, with evidence of multiple clusters and sub-clusters within sub-lineage 2a, highlighting the complex and dynamic circulation of WNV in Romania, as a consequence of distinct introduction events from neighboring countries followed by in situ evolution.