Colonization Rates Research Articles

Clinical audit on antimicrobial stewardship effectiveness to reduce antimicrobial resistance bacteria colonisation rates in an equine veterinary teaching hospital

Clinical audit on antimicrobial stewardship effectiveness to reduce antimicrobial resistance bacteria colonisation rates in an equine veterinary teaching hospital

Dynamic occupancy modelling of Asian elephants (Elephas maximus) reveals increasing landscape use in Nepal

Large mammals with general habitat needs can persist throughout mixed used landscapes, however, human-wildlife conflict frequently leads to their restriction to protected areas. Conservation efforts, especially for reducing conflicts with humans, can enhance tolerance of humans towards species like Asian elephants (Elephas maximus) in human-dominated landscapes. Here, we examine how elephant use in the Chure Terai Madhesh Landscape (CTML) covering the entire elephant range of Nepal changed between 2012 and 2020 in relationship to protection status and environmental conditions. We systematically surveyed ~ 42,000 km2 of potential habitat, by dividing the study area into 159 grid cells of 15 × 15 km2 and recorded elephant signs during the cool, dry season in three years (2012, 2018 and 2020). We analyzed the survey data in a single-species, multi-season (dynamic) occupancy modeling framework to test hypotheses regarding the influence of environmental conditions and protected area status on landscape use by elephants over time. The best-supported model included protected area effects on initial use, colonization, and detection probability as well as temporal variation in colonization and detection probability. Initial use and colonization rates were higher in protected areas, however elephants increasingly used cells located both inside and outside the protected areas, and the difference in use between protected areas and outside declined as elephants use became prevalent across most of the landscape. While elephant use was patchily distributed in the first year of surveys consistent with past descriptions of four sub-populations, elephant use consolidated into a western and eastern region in subsequent years with a gap in their distribution occurring between Chitwan and Bardiya National Parks. Our manuscript highlights the increasing landscape use by elephants in both protected areas and areas outside protected areas and suggests that management interventions that focus on reducing conflicts can promote greater use of both protected areas and areas outside of protected areas.

Morphological type and taxonomic diversity of arbuscular mycorrhizal fungi along an altitudinal gradient at Mount Ibuki, Japan

ABSTRACT Arbuscular mycorrhiza (AM) associations are among the most widespread interactions between plants and fungi. However, little is known about the AM distribution along altitudinal gradients in forest ecosystems, where the gradients are accompanied by shifts in climatic conditions and soil properties as well as the identity of host plant species. This study aimed to clarify AM fungal associations along an altitudinal gradient. Therefore, we determined the colonization rate and community composition of AM fungi at different elevations on Mount Ibuki, Japan. Root and soil samples were collected from Cryptomeria japonica at altitudes of 200, 500, and 800 m, Acer shirasawanum at an altitude of 1100 m, and Chrysanthemum japonicum at the summit of 1350 m. To evaluate AM fungal colonization, 15 root samples from each altitude were examined microscopically. These samples were identified by targeting V4 and V5 regions of a partial small subunit rRNA gene using Sanger sequencing. AM fungal colonization rates were significantly and positively correlated with altitude. The Arum and Paris types were observed in all plant species examined at each altitude. In total, 101 molecular operational taxonomic units belonging to two genera were identified: Glomus and Diversispora. No significant clustering among elevations was observed in the AM fungal community composition. Among environmental variables, soil temperature, and pH significantly affected AM fungal structure patterns. These results suggest that as altitude increases, plants require more tight mycorrhizal associations, which are selectively filtered by the surrounding environment.

Effects of long-term nitrogen addition on root nitrogen acquisition strategy: Insights from a 19-year experiment in two temperate tree species

Nitrogen (N) serves as the primary limiting nutrient for plant growth in the majority of terrestrial ecosystems. However, the effect of long-term N addition on root N acquisition, in particular the seasonal dynamics, is still not well understood. In a 19-year N addition experiment on plantations of ectomycorrhizal tree species Larix gmelinii (larch) and arbuscular mycorrhizal tree species Fraxinus mandshurica (ash), we determined root morphological, chemical and mycorrhizal traits, as well as soil properties. Concurrently, we used a field isotopic hydroponic method to measure root uptake rates of NH4+, NO3-, and glycine in the early, mid and late growing season. Following N addition, mycorrhizal colonization rates in both species were reduced in early and late growing season. Root tissue density was reduced but specific root length and area were increased in ash under N addition across growing seasons, however, no significant differences in these traits were found in larch. Under N addition, both species showed lower uptake rates of all N forms and the total N than the controls throughout the growing season, except for the glycine-uptake of larch in early growing season. N addition did not modify the N-uptake preference in both species, but the contributions of specific N form to the total N varied with seasons. Collectively, referring to the framework of “root economics space”, these two species particularly ash showed greater reliance on the “do-it-yourself” strategy for N acquisition under long-term N addition, although the degree of which somewhat varied with season. Seasonal dynamics in root N-uptake rates of ash were mainly related to soil temperature and moisture, rather than soil N properties, showing less direct impact of N addition. Our findings provide deep insights into the effect of N deposition on root N acquisition strategy and related functions of forest ecosystem.

GDNF's Role in Mitigating Intestinal Reactive Gliosis and Inflammation to Improve Constipation and Depressive Behavior in Rats with Parkinson's disease.

Constipation is a common symptom in patients with Parkinson's disease (PD) and is often associated with depression. Enteric glial cells (EGCs) are crucial for regulating intestinal inflammation and colon motility, and their activation can lead to the death of intestinal neurons. Glial cell line-derived neurotrophic factor (GDNF) has been recognized for its neuroprotective properties in various neurological disorders, including PD. This study explores the potential of GDNF in alleviating intestinal reactive gliosis and inflammation, thereby improving constipation and depressive behavior in a rat model of PD.A PD model was established via unilateral stereotaxic injection of 6-hydroxydopamine (6-OHDA). Five weeks post-injury, AAV5-GDNF (2 ~ 5 × 10^11) was intraperitoneally injected into experimental and control rats. Fecal moisture percentage (FMP) and colonic propulsion rate (CPPR) were used to evaluate colon motility. Colon-related inflammation and colonic epithelial morphology were assessed, and depressive behavior was analyzed one week before sampling.PD rats exhibited reduced colonic motility and GDNF expression, along with increased EGC reactivity and elevated levels of pro-inflammatory cytokines IL-1, IL-6, and TNF-α. Additionally, there was an up-regulation of CX43 and a decrease in PGP 9.5 expression. The intraperitoneal injection of AAV-GDNF significantly protected colonic neurons by inhibiting EGC activation and down-regulating CX43. This treatment also led to a notable reduction in depressive-like symptoms in PD rats with constipation.GDNF effectively reduces markers of reactive gliosis and inflammation, and promotes the survival of colonic neurons, and improves colonic motility in PD rats by regulating CX43 activity. Furthermore, GDNF treatment alleviates depressive behavior, suggesting that GDNF or its agonists could be promising therapeutic agents for managing gastrointestinal and neuropsychiatric symptoms associated with PD.

Pneumonia due to Mycoplasma hominis in a Full-Term Newborn - A Case Report with Literature Review

Mycoplasma ssp can colonize various human tissues and can cause infections. Their lack of a cell wall makes them difficult to cultivate and to treat as they are resistant to beta-lactam antibiotics. Mycoplasma hominis and ureaplasma urealyticum can colonize the genital tract. While colonization in healthy adults is usually asymptomatic, they can cause neonatal infections during pregnancy through transmission to the fetus or during birth and lead to increased morbidity and mortality, especially in premature infants. However, in full-term neonates with high colonization rates, the pathogenic role and its treatment is controversial. In the following, we present a case of neonatal pneumonia caused by M. hominis in a full-term neonate, which was successfully treated with clindamycin. Mycoplasma spp. can cause symptomatic infections in neonates in individual cases and should be considered as potential pathogens, especially in the case of a protracted course.

Synergistic effects of combined application of biochar and arbuscular mycorrhizal fungi on the safe production of rice in cadmium contaminated soil

Arbuscular mycorrhizal fungi (AMF) have been shown to effectively mitigate the detrimental effects of heavy metal stress on their plant hosts. Nevertheless, the biological activities of AMF were concurrently compromised. Biochar (BC), as an abiotic factor, had the potential compensate for this limitation. To elucidate the synergistic effects of biotic and abiotic factors, a pot experiment was conducted to assess the impact of biochar and AMF on the growth, physiological traits, and genetic expression in rice plants subjected to Cd stress. The results demonstrated that biochar significantly increased the mycorrhizal colonization rate by 22.19 %, while the combined application of biochar and AMF led to a remarkable enhancement of rice root biomass by 42.2 %. This resulted in a shift in spatial growth patterns that preferentially promoted enhanced underground development. Biochar effectively mitigated the stomatal limitations imposed by Cd on photosynthetic processes. The decrease in IBRv2 (Integrated Biomarker Response version 2) values suggested that the antioxidant system was experiencing a state of remission. An increase of Cd content within the rice root systems was observed, ranging from 33.71 % to 48.71 %, accompanied by a reduction in Cd bioavailability and mobility curtailed its translocation to the aboveground tissues. Under conditions of low soil Cd concentration (Cd ≤ 1 mg·kg−1), the Cd content in rice seeds from the group subjected to the combined treatment remained below the national standard (Cd ≤ 0.2 mg·kg−1). Furthermore, the combined treatment modulated the uptake of Fe and Zn by rice, while simultaneously suppressing the expression of genes associated with Cd transport. Collectively, the integration of biological and abiotic factors provided a novel perspective and methodological framework for safe in-situ utilization of soils with low Cd contamination.

Engineering a Novel Probiotic Toolkit in Escherichia coli Nissle 1917 for Sensing and Mitigating Gut Inflammatory Diseases.

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation with no cure and limited treatment options that often have systemic side effects. In this study, we developed a target-specific system to potentially treat IBD by engineering the probiotic bacterium Escherichia coli Nissle 1917 (EcN). Our modular system comprises three components: a transcription factor-based sensor (NorR) capable of detecting the inflammation biomarker nitric oxide (NO), a type 1 hemolysin secretion system, and a therapeutic cargo consisting of a library of humanized anti-TNFα nanobodies. Despite a reduction in sensitivity, our system demonstrated a concentration-dependent response to NO, successfully secreting functional nanobodies with binding affinities comparable to the commonly used drug Adalimumab, as confirmed by enzyme-linked immunosorbent assay and in vitro assays. This newly validated nanobody library expands EcN therapeutic capabilities. The adopted secretion system, also characterized for the first time in EcN, can be further adapted as a platform for screening and purifying proteins of interest. Additionally, we provided a mathematical framework to assess critical parameters in engineering probiotic systems, including the production and diffusion of relevant molecules, bacterial colonization rates, and particle interactions. This integrated approach expands the synthetic biology toolbox for EcN-based therapies, providing novel parts, circuits, and a model for tunable responses at inflammatory hotspots.

Arbuscular Mycorrhizal Fungal Interacted with Biochar and Enhanced Phosphate-Solubilizing Microorganism Abundance and Phosphorus Uptake in Maize

In agricultural production, it is crucial to increase the availability of phosphorus (P) in cultivated soil to solve the P limitation. Arbuscular mycorrhizal fungi (AMF) have been proven to promote crop nutrient absorption effectively, while biochar can lead to improvements in soil properties. However, the possible synergistic effect of AMF and biochar on P uptake by crops as well as its underlying mechanisms are unclear. In this study, we conducted a pot experiment to explore the effects of biochar and AMF (Glomus etunicatum) on the community of rhizospheric phosphate-solubilizing microorganisms (PSMs) of maize (Zea mays L. Xianyu-335) using metagenomic methods. The experiment used 0 mg P2O5 g·kg−1 soil (P0) and 30 mg P2O5 g·kg−1 soil (P30) application rates. Each P application rate included 0 (NC), 20 g·kg−1 biochar (BC) addition, inoculation AMF, and without AMF treatments (NM) for a total of eight treatments. During the experiment, both the P uptake and the biomass of maize were measured. The study found that the combination of AMF and biochar significantly increased the mycorrhizal colonization rate of maize roots, regardless of P application level. It was observed that the P uptake by maize was significantly increased when exposed to a combination of AMF and biochar. The increase in P uptake in P0 treatments was 67% higher than the sum of the effects of biochar and AMF inoculation alone. The increase was only 35% higher in P30 treatments, demonstrating a substantially higher interactive effect under P0 than under P30 conditions. The AM-BC treatments significantly increased the abundance of Streptomyces, Bacillus, and Pseudomonas, genera that are known to contain PSMs. In addition, the abundance of genes related to P-cycling (gcd, phoD, and ugpQ) in PSMs increased significantly by 1.5–1.8 times in AM-BC treatments compared with NM-BC and AM-NC treatments under P0 conditions. This increase was significantly and positively correlated with the P uptake. Overall, the results suggest that biochar can help AMF colonize the roots, increasing the functional roles of PSMs in the rhizosphere, which in turn promotes P uptake and biomass in maize. This study provides a new way to improve P-use efficiency and reduce the need for P-fertilizer application in agricultural production.

Iron Nanostructure Primes Arbuscular Mycorrhizal Fungi Symbiosis Tightly Connecting Maize Leaf Photosynthesis via a Nanofilm Effect.

It is crucial to clarify how the iron nanostructure activates plant growth, particularly in combination with arbuscular mycorrhizal fungi (AMF). We first identified 1.0 g·kg-1 of nanoscale zerovalent iron (nZVI) as appropriate dosage to maximize maize growth by 12.7-19.7% in non-AMF and 18.9-26.4% in AMF, respectively. Yet, excessive nZVI at 2.0 g·kg-1 exerted inhibitory effects while FeSO4 showed slight effects (p > 0.05). Under an appropriate dose, a nano core-shell structure was formed and the transfer and diffusion of electrons between PS II and PS I were facilitated, significantly promoting the reduction of ferricyanide and NADP (p < 0.05). SEM images showed that excessive nZVI particles can form stacked layers on the surface of roots and hyphae, inhibiting water and nutrient uptake. TEM observations showed that excessive nanoparticles can penetrate into root cortical cells, disrupt cellular homeostasis, and substantially elevate Fe content in roots (p < 0.05). This exacerbated membrane lipid peroxidation and osmotic regulation, accordingly restricting photosynthetic capacity and AMF colonization. Yet, appropriate nZVI can be adhered to a mycelium surface, forming a uniform nanofilm structure. The strength of the mycelium network was evidently enhanced, under an increased root colonization rate and an extramatrical hyphal length (p < 0.05). Enhanced mycorrhizal infection was tightly associated with higher gas exchange and Rubisco and Rubisco enzyme activities. This enabled more photosynthetic carbon to input into AMF symbiont. There existed a positive feedback loop connecting downward transfer of photosynthate and upward transport of water/nutrients. FeSO4 only slightly affected mycorrhizal development. Thus, it was the Fe nanostructure but not its inorganic salt state that primed AMF symbionts for better growth.

The Roles of a Multidrug-Resistant Klebsiella pneumoniae High-Risk Clone and Its Resistance Plasmids on the Gastrointestinal Colonization and Host-Defense Effectors in the Gut.

The asymptomatic gastrointestinal colonization of multidrug-resistant (MDR) bacteria can lead to difficult-to-treat infections. We investigated the role of host factors influencing colonization in an orogastrical murine infection model using a CTX-M-15- and OXA-162-producing Klebsiella pneumoniae ST15 (MDR-KP) strain, as well as Escherichia coli J53 (EC) and E. coli transconjugants with an IncFII(K) plasmid carrying CTX-M-15 (EC-CTXM), and with an IncL plasmid carrying OXA-162 (EC-OXA) genes. The fecal bacterial count in colony-forming unit/gram stool (CFU/g) was determined by cultivation, IgA and defensin levels by ELISA, and gut microbiota by 16S rRNA analysis. The CFU was the lowest in EC, followed by EC-OXA and EC-CTXM, and the highest in the MDR-KP group. The IgA level in feces increased in MDR-KP, EC-CTXM, and EC-OXA, and did not change in EC. The beta-defensin 3 level markedly increased in all groups, with the highest values in MDR-KP and EC-CTXM. Alpha-defensin-5 increased in all groups especially in EC. In microbiota, the Bacteroidota phylum was dominant in MDR-KP, EC-CTXM, and EC-OXA, whereas Proteobacteria was dominant in EC. The Muribaculaceae family was significantly more common in the MDR-KP and EC-OXA groups, while the Lachnospiraceae family was dominant in the EC group. While fecal IgA levels positively correlated with colonizing bacterial CFU, the alpha-defensin 5 levels inversely correlated with CFUs and IgA levels. The presence of the IncFII(K) plasmid induced beta-defensin 3 production. The amounts of the Muribaculaceae family members exhibited a correlation with the IncL plasmid. The detected amounts of the Lachnospiraceae family indicated the protective role against the high-risk clone and the resistance plasmids' dissemination. Our results suggest that not only the MDR-KP clone itself but also the resistance plasmids play a primary role in the colonization rate in the gastrointestinal tract. Both the MDR-KP clone as well as the IncFII(K) and IncL resistance plasmids provide survival and colonization benefits in the gut.

Factors influencing the epibiota of granite blocks used in coastal defense structures: An observational experiment

Anthropogenic pressures exerted on coastal areas, combined with climate change, and accelerated sea level rise, result in the loss of natural habitats. At the same time, the number of coastal protection and defense structures have increased considerably and may become the dominant habitat in many intertidal regions. In this study we characterize the epibiota of artificial substrates (granite blocks) from coastal defense structures used to contain the effects of rising sea levels, and the same type of artificial substrate found in contact with coastal reefs located on Serrambi beach, northeast of Brazil. We mapped, measured, and photographed 45 artificial granite blocks and their surroundings in the field. A gradient was found for the number of taxa on the blocks, from high coverage by macroalgae to extensive non-colonized areas. However, it was observed that the closer to the natural reef the greater the taxonomic richness. Our results also indicate that the factor that best explains the colonization of blocks is the coverage of their surroundings, thus, few organisms were found on blocks whose surrounding unconsolidated sediment area was very extensive. In our wind and sun exposure simulation, granite rock demonstrated a more accelerated and greater level of heating (up to 3 °C) compared to fragments of natural substrate, although the variation in the slightly lighter colored and smaller granite block resembles the variation in the reef fragment. We suggest that the use of lighter-colored granite blocks at mid-coastal levels can increase the colonization rate of these substrates.

A novel polyp retrieval bag reduces the polyp fragmentation rate in colon polypectomy: a single-blind randomized controlled study

PurposeThe fragmentation of polyps affects complete resection confirmation. The primary aim of this study was to assess the feasibility of a novel polyp retrieval bag for reducing the fragmentation rate of colon polyps.MethodsPatients with a 5–15 mm colon polyp were recruited and randomized into two groups at a 1:1 ratio. After polyp resection, polyps obtained from patients in the treatment group were extracted via a novel polyp retrieval bag without traversing the instrument channel, whereas polyps obtained from patients in the control group were collected through the instrument channel, attaching the polyp trap to the instrument channel port, and applying suction.ResultsFrom January to July 2022, 225 patients were assessed for eligibility. The study participants included 204 patients, and seven patients whose samples were not retrieved were excluded. Polyp fragmentation was significantly lower in the treatment group than in the control group (3.0% [3/100] vs. 17.5% [17/97], P = 0.001). The retrieval failure rates in the treatment group and control group were not significantly different (2.0% [2/102] vs. 4.9% [5/102], P = 0.442). There were fewer colonoscope insertions in the treatment group than in the control group (102 vs. 110), but a significant difference was not present (P = 0.065). No significant adverse events were observed during the follow-up.ConclusionsThis study demonstrated that the polyp retrieval bag was safe and feasible for reducing the fragmentation rate of retrieved polyps.Trial registrationThe study was registered at ClinicalTrials.gov (NCT05189912, 1/12/2021).

Bio-encapsulation of Microbial Biostimulant for Drought Resilience in Groundnut (Arachis hypogaea L.)

ABSTRACT Plant growth promoting rhizobacteria (PGPR) as microbial biostimulant promotes growth and productivity of crops under drought. However, their commercial utility is constrained by their instability and low viability in field trials. Immobilization or encapsulation of PGPR biostimulant aims to provide physical protection from stressful environment and ensure a high rate of rhizospheric colonization. In this work, we immobilized Acinetobacter calcoaceticus AC01 in 2% alginate by ionic gelation process, and evaluated for in vitro and in vivo studies. The rhizobacteria was characterized for osmotic stress, indole, phosphate solubilization, siderophore, gibberellic acid, salicylic acid, alginate and Exopolysaccharide (EPS). The encapsulated PGPR AC01 exhibited optimal moisture content of 3.57%, expansion rate of 80.62%, 95% embedding efficiency and diameter of 1.2–1.4 mm. The viability of AC01 in microcapsules remained 107CFU/g during 90 days of storage. The encapsulated PGPR biostimulant were also evaluated in Arachis hypogaea L. for drought mitigation. The inclusion of rhizobacterial microcapsules considerably induced maximum growth with significantly increased plant height, biomass, nodule count, relative water content, membrane stability index and osmolyte accumulation under drought conditions compared to non-encapsulated bacteria. Our results demonstrate that bio-encapsulation of Acinetobacter sp. AC01 in alginate matrix is a potential alternative for alleviating drought and a promising delivery system for agricultural applications.

Arbuscular Mycorrhizal Fungi Mediate the Acclimation of Rice to Submergence.

Flooding is a critical factor that limits the establishment of a symbiosis between rice and arbuscular mycorrhizal fungi (AMF) in wetland ecosystems. The distribution of carbon resources in roots and the acclimation strategies of rice to flooding stress in the presence of AMF are poorly understood. We conducted a root box experiment, employing nylon sheets or nylon meshes to create separate fungal chambers that either prevented or allowed the roots and any molecules to pass through. We found that the mycorrhizal colonization rate and the expression of genes OsD14L and OsCERK1, which are involved in fungal perception during symbiosis, both increased in mycorrhizal rice roots following intermittent flooding compared to continuous flooding. Furthermore, AMF inoculation affected root morphological traits, facilitating both shallower and deeper soil exploration. Increased submergence intensity led to carbohydrate deprivation in roots, while high mycorrhizal colonization increased soil oxygen consumption and decreased the neutral lipid concentration in roots. However, mycorrhizal inoculation increased the rice photosynthesis rate and facilitated acclimation to submergence by mediating the expression of the genes OsCIPK15 and OsSUB1A to enhance rice shoot elongation and the sugar concentration in roots as a result of reduced competition for carbon between rice and AMF under different flooding conditions.

Effect of chemotherapeutic agents on natural transformation frequency in Acinetobacter baylyi.

Natural transformation is the ability of a bacterial cell to take up extracellular DNA which is subsequently available for recombination into the chromosome (or maintenance as an extrachromosomal element). Like other mechanisms of horizontal gene transfer, natural transformation is a significant driver for the dissemination of antimicrobial resistance. Recent studies have shown that many pharmaceutical compounds such as antidepressants and anti-inflammatory drugs can upregulate transformation frequency in the model species Acinetobacter baylyi. Chemotherapeutic compounds have been shown to increase the abundance of antimicrobial resistance genes and increase colonization rates of potentially pathogenic bacteria in patient gastrointestinal tracts, indicating an increased risk of infection and providing a pool of pathogenicity or resistance genes for transformable commensal bacteria. We here test for the effect of six cancer chemotherapeutic compounds on A. baylyi natural transformation frequency, finding two compounds, docetaxel and daunorubicin, to significantly decrease transformation frequency, and daunorubicin to also decrease growth rate significantly. Enhancing our understanding of the effect of chemotherapeutic compounds on the frequency of natural transformation could aid in preventing the horizontal spread of antimicrobial resistance genes.

Evaluation of the Colonization of Plants from Five Quercus Taxa Native to Greece by Tuber aestivum (Ascomycota, Pezizales).

Fungi of the genus Tuber are famous for their hypogeous ascomata (truffles), many of which possess noteworthy organoleptic properties. T. aestivum shows a wide geographic distribution, has many plant symbionts and is well adapted to various climatic conditions. In this study, five Quercus taxa native to Greece (i.e., Q. coccifera, Q. ilex, Q. ithaburensis subsp. macrolepis, Q. pubescens and Q. trojana subsp. trojana) were inoculated with spore suspensions obtained from a single ascoma of T. aestivum. The fungal colonization of oak roots was evaluated at three, seven and 12 months after inoculation; the respective colonization rates for each time period were as follows: low to medium (17-41%) for Q. pubescens, Q. ithaburensis subsp. macrolepis and Q. trojana subsp. trojana, medium to relatively high (58-80%) for Q. ithaburensis subsp. macrolepis, Q. ilex, Q. pubescens and Q. trojana subsp. trojana, and medium to high (45-87%) for all oak species examined. Positive correlations were assessed between the number of colonized root tips and the total root tips number, but no significant differences were detected between the inoculated plants and the respective control as regards plant growth. The ectomycorrhizae formed by T. aestivum with Q. ithaburensis subsp. macrolepis and Q. trojana subsp. trojana are described for the first time. The outcome of the study evidences the feasibility of generating the seedlings of various indigenous oak species (covering a large range of diverse habitats) successfully inoculated with autochthonous truffles to be readily used for cultivation purposes.

Interactions between an arbuscular mycorrhizal inoculum and the root-associated microbiome in shaping the response of Capsicum annuum “Locale di Senise” to different irrigation levels

Abstract Background and aims The use of root-associated microorganisms emerge as a sustainable tool to enhance crop tolerance and productivity under climate change, particularly in drought-affected areas. Here, the impact of an inoculum based on arbuscular mycorrhizal fungi (AMF) was evaluated on pepper (Capsicum annuum L.) cultivation at varying water irrigation treatments (well-watered, reduced irrigation and rain-fed) under open-field conditions. Methods Agronomic and ecophysiological parameters, as well as biochemical analyses on stress markers and phytohormones in leaves and on fruit quality traits, were evaluated, along with the shifts in soil- and root-associated microbial communities. Results Rain-fed water treatment caused reduced fruit sizes, while no differences were detected among well-watered and reduced irrigation. Reduced irrigation did not cause a reduction in stomatal conductance. The highest AM fungal colonization rates were observed under reduced irrigation, and the enhanced flavonoid content and reduced oxidative stress markers in AMF-inoculated plants suggested a synergistic effect of AM fungal inoculation in boosting plant tolerance against stress. A shift in microbial community composition in the different irrigation treatments, associated with different enzymatic activity, highlighted the potential role of microbial dynamics in plant stress response under water-limited conditions. Conclusion The study suggests that a reduced irrigation comes along with beneficial impacts on pepper root associated microbes, while not impairing crop performance and yields, indicating a potential of saving water. All together, our results imply that optimization of irrigation and beneficial plant–microbe interactions, such as AM fungal symbiosis, can improve pepper physiological and productivity features under climate change.

Risk factors and molecular epidemiology of intestinal colonization by carbapenem-resistant Gram-negative bacteria in patients with hematological diseases: a multicenter case‒control study.

Patients with hematological diseases are considered to be at high risk for intestinal colonization by carbapenem-resistant Gram-negative bacteria (CR-GNB). However, the epidemiological data regarding risk factors and molecular characteristics of intestinal colonized CR-GNB isolates in this population are insufficient in China. A multicenter case‒control study involving 4,641 adult patients with hematological diseases from 92 hospitals across China was conducted. Following culture of collected rectal swabs, mass spectrometry and antimicrobial susceptibility tests were performed to identify GNB species and CR phenotype. Risk factors were assessed through retrospective clinical information. Whole-genome sequencing was used to analyze the molecular characteristics of CR-GNB isolates. This trial is registered with ClinicalTrials.gov as NCT05002582. Our results demonstrated that among 4,641 adult patients, 10.8% had intestinal colonization by CR-GNB. Of these, 8.1% were colonized by carbapenem-resistant Enterobacterales (CRE), 2.6% were colonized by carbapenem-resistant Pseudomonas aeruginosa (CRPA), and 0.3% were colonized by carbapenem-resistant Acinetobacter baumannii (CRAB). The risk factors for CR-GNB colonization include male gender, acute leukemia, hematopoietic stem cell transplantation, β-lactam antibiotic usage, and the presence of non-perianal infections within 1 week. Compared with CRPA-colonized patients, patients using carbapenems were more likely to be colonized with CRE. NDM was the predominant carbapenemase in colonized CRE. This study revealed a high CR-GNB intestinal colonization rate among adult patients with hematological diseases in China, with CRE being the predominant one. Notably, a significant proportion of CRE exhibited metallo-β-lactamase production, indicating a concerning trend. These findings emphasize the importance of active screening for CR-GNB colonization in patients with hematological diseases.IMPORTANCECarbapenem-resistant Gram-negative bacteria (CR-GNB) has emerged as a significant threat to public health. Patients with hematological diseases are at high risk of CR-GNB infections due to their immunosuppressed state. CR-GNB colonization is an independent risk factor for subsequent infection. Understanding the risk factors and molecular characteristics of CR-GNB associated with intestinal colonization in patients with hematological diseases is crucial for empirical treatment, particularly in patients with febrile neutropenia. However, the epidemiology data are still insufficient, and our study aims to determine the intestinal colonization rate of CR-GNB, identify colonization risk factors, and analyze the molecular characteristics of colonized CR-GNB isolates.

Two lysin motif extracellular (LysMe) proteins are deployed in rice to facilitate arbuscular mycorrhizal symbiosis.

During arbuscular mycorrhizal (AM) symbiosis, plant innate immunity is modulated to a prime state to allow for fungal colonization. The underlying mechanisms remain to be further explored. In this study, two rice genes encoding LysM extracellular (LysMe) proteins were investigated. By obtaining OsLysMepro:GUS transgenic plants and generating oslysme1, oslysme2 and oslysme1oslysme2 mutants via CRISPR/Cas9 technique, OsLysMe genes were revealed to be specifically induced in the arbusculated cells and mutations in either gene caused significantly reduced root colonization rate by AM fungus Rhizophagus irregularis. Overexpression of OsLysMe1 or OsLysMe2 dramatically increased the colonization rates in rice and Medicago truncatula. The electrophoretic mobility shift assay and dual-luciferase reporter assay supported that OsLysMe genes are regulated by OsWRI5a. Either OsLysMe1 or OsLysMe2 can efficiently rescue the impaired AM phenotype of the mtlysme2 mutant, supporting a conserved function of LysMe across monocotyledonous and dicotyledonous plants. The co-localization of OsLysMe proteins with the apoplast marker SP-OsRAmy3A implies their probable localization to the periarbuscular space (PAS) during symbiosis. Relative to the fungal biomass marker RiTEF, some defense-related genes showed disproportionately high expression levels in the oslysme mutants. These data support that rice plants deploy two OsLysMe proteins to facilitate AM symbiosis, likely by diminishing plant defense responses.