Total Colonization Research Articles

Weathering Resistance of Wood Following Thermal Modification in Closed Process Under Pressure in Nitrogen

The wood of Scots pine (Pinus sylvestris), silver birch (Betula pendula), and European aspen (Populus tremula) was thermally modified in nitrogen under pressure. Three commercial linseed oil-based coatings without or with brown and grey pigments were applied to the specimens. Specimens were placed outside, and weathering stability was assessed for 3 months. The test measured total surface colour change (ΔE) and colonization by wood dicolouring fungi. Following the test, all uncoated specimens demonstrated poor colour fastness and resistance to fungal growth. All tested coatings were unsuitable for protecting untreated wood from dicolouring fungi. The transparent coating was inefficient since it did not significantly prevent untreated or TM wood from fading, and fungal resistance was increased only for a few TM regimes. The colour fastness of specimens with pigmented coatings was enhanced. Specimens with a grey coating exhibited the lowest ΔE and remained consistent throughout the test period. TM specimens with coloured surfaces exhibited greater fungal resistance. However, not all TM aspen and birch regimes had a sufficient growth mark (rating 0 or 1). TM aspen was less resistant to fungi, whereas TM pine displayed very strong fungal resistance across all TM regimes.

Dynamics of Arbuscular Mycorrhizal Fungi in the Rhizosphere of Medicinal Plants and Their Promotion on the Performance of Astragalus mongholicus

Arbuscular mycorrhizal fungi (AMF) act as intermediaries between the root systems of host plants and the surrounding soil, offering various benefits to medicinal plants, such as promoting growth and enhancing quality. However, the host range of AMF in medicinal plants and the characteristics of plant–AMF networks in farmland ecosystems remain insufficiently studied. In the present study, we measured AMF colonization, species diversity, and soil properties of 31 medicinal plants at the Anguo Medicine Planting Base in Northwest China. The medicinal plant–AMF network was subsequently analyzed, and the growth-promoting effects of AMF on Astragalus mongholicus were examined. Spore density, species richness, and total colonization exhibited significant variation across different medicinal plant species. Glomus melanosporum, G. claroideum, and Septoglomus constrictum were the dominant species among 61 AMF species. Soil organic matter, phosphatase, available nitrogen, and glomalin-related soil proteins (GRSPs) were the main factors affecting the AMF composition. Structural equation models and a variation partitioning analysis suggested a highly plant species-specific pattern of AMF distribution patterns, where the host identities explained 61.4% of changes in spore density and 48.2% of AMF colonization. The soil nutrient availability and phosphatase activity also influenced AMF colonization. Our results confirmed glomalin as an important contributor to the soil carbon in farmland for cultivating medicinal plants. The medicinal plant–AMF symbiotic network exhibited highly nested patterns, a low specialized structure, high connectance, and low modularity, which suggested saturated AMF colonization and symbiosis stability provided by redundant plant–AMF associations. Despite the wide host range among medicinal plants, AMF inoculation revealed species-specific effects on the growth performance and active ingredient content levels in A. mongholicus, G. claroideum and Sep. constrictum induced the highest biomass and active ingredient content accumulation in A. mongholicus. These findings advance our understanding of AMF community dynamics in the rhizosphere of medicinal plants and offer valuable insights for optimizing medicinal plant cultivation practices.

Ectomycorrhizal Diversity and Exploration Types in Salix caprea

The tree species Salix caprea shows high adaptability to different habitat conditions and is economically valuable as a woody crop for biomass production. Moreover, S. caprea is dependent on mycorrhizal fungi, which are crucial for its growth and adaptability in different environments. Hence, this study explores the ectomycorrhizal diversity of S. caprea by utilizing the taxonomy (morphotyping and a molecular approach using the ITS and LSU regions) and trait diversity (exploration types) at two test sites in Germany and Poland. In total, 19 ectomycorrhizal (EM) morphotypes of S. caprea were characterized. Seven taxa were identified at the species level (Hebeloma populinum, Cortinarius atrocoerulaeus, Inocybe hirtella, Laccaria cf. ochropurpurea, Tuber maculatum, Cenococcum geophilum, and Phialophora finlandia) and twelve at the genus level (Tomentella spp. 1–8, Hebeloma sp. 1, Inocybe sp. 1, and Tuber spp. 1–2). The EM colonization ranged from 14 to 28% of the fine root tips. At both test sites, the largest portion of the total EM colonization consisted of Thelephoraceae. The exploration types were classified as medium-distance smooth (Tomentella sp. 1–8 and L. ochropurpurea) and medium-distance fringe (C. atrocoerulaeus), while the other taxa were short-distance exploration types, highlighting their potential functional role in the adaptation and growth of S. caprea.

KIRIM SAVAŞI'NDA KUZEY KAFKASYA

The Crimean War is one of the important turning points in Ottoman-Russian relations. While the Ottoman Empire tried to maintain its declining influence in the Black Sea with the support of its European allies, Russia tried to increase its influence in both the Balkans and the North Caucasus. Against this policy of Russia, the resistance groups in the North Caucasus tried to gain the support of the Ottoman Empire and its allies, while trying to create unity among themselves. The movements in the North Caucasus, which were far from forming any unity and providing organized resistance, ended after the war when Russia launched a total occupation and colonization activity in the Caucasus region. The war and resistance in the region gave way to one of the greatest tragedies in history, in which hundreds of thousands of Circassians were exiled and subjected to massacres. In this study, the situation in the North Caucasus during and after the Crimean War will be evaluated.

Elevating Sorghum Prosperity: Unveiling Growth Trends through Phosphate-Solubilizing Bacteria and Arbuscular Mycorrhizal Fungi Inoculation in Phosphate-Enriched Substrates

This study aimed to elucidate the impact of phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) inoculation on sorghum growth within substrates derived from phosphate solid sludge, with the overarching objective of repurposing phosphate sludge to be a viable agricultural substrate. Four PSB strains (Serratia rubidaea, Enterobacter bugandensis, Pantoea agglomerans, Pseudomonas sp.) were meticulously selected from phosphate solid sludge, along with two AMF strains (Rhizophagus intraradices and Funneliformis mosseae), constituting the experimental inocula. Phosphate solid sludge was judiciously blended with peat at varying volumetric proportions (0%, 10%, 20%, 40%, and 60%), providing the matrix for sorghum cultivation, and concomitantly subjected to inoculation with PSB and AMF. Following a meticulously monitored two-month duration, a comprehensive evaluation of diverse morphological parameters, biomass accrual, nitrogen content, total phosphorus concentration, potassium levels, calcium content, and root colonization in sorghum plants was conducted. The empirical findings underscored a discernible decline in the assessed parameters with escalating concentrations of phosphate solid sludge. Particularly noteworthy was the pronounced amelioration observed in plants inoculated with AMF in comparison to both the control and PSB-inoculated counterparts. In conclusion, the application of raw phosphate solid sludge as an agricultural substrate is deemed unsuitable, prompting the imperative need for further in-depth investigations to ascertain the nuanced intricacies underlying these outcomes.

Morphological and Molecular Characterisation of Endophytic Fungi Isolated from Moringa oleifera Leaves in Iraq and Chemical Analysis of Leaves Extracts Using GC-Mass

Endophytic fungi are found inside plants, with no disease appearance; in contrast, they improve the growth of plants spatially in limited habitats. This study aimed to isolate and characterize, morphologically and genetically endophytic fungi gathered from Moringa oleifera leaves, as well as detect the chemical components in the leaves using GC-Mass spectrometry. the results obtained that 59 endophytic fungi isolates were detected, with a total colonisation rate of 84.26%. These fungi belong to 8 types, where Aspergillus was a predominated genus with 5 species. Besides, A. flavus was prevalent with a colonisation rate of 27.14, and A. niger with a rate of 15.71; Byssochlays spectabilis with a rate of 28%. Moreover, the result of chemical components analysis in leaves using GC-mass showed the presence of active 30 compounds. including oleic acid, phytol, octadecenoic acid, hexadecanoic acid, methyl ester and phenol.

Isolation and Identification of Endophytic Fungi from Aloe vera Leaves and Chemical Analysis of the Alcoholic Extract of the Leaves Using HPLC, GC, and GC-Mass Devices

The study's goals were to separate and identify endophytic fungi from Aloe vera leaves by looking at their morphology and molecules, as well as to find the chemical compounds in the leaf extract by using HPLC, GC, and GC-Mass instruments. The results showed that 53 endophytic fungi were isolated from a total of 120 pieces of A. vera leaves, with a total colonization rate of 44.16%. The fungus Aspergillus terreus had a colonization rate of 14.16%; Aspergillus niger had a colonization rate of 13.33%; Penicillium chermesinum demonstrated a colonization rate of 6.66%; Paecilomyces variotii had a colonization rate of 2.5%; Talaromyces radicus; and Aspergillus flavus achieved a colonization rate of 1.66%. Finally, the fungi Aspergillus quadrilineatus, Talaromyces verruculosus, Neoscytalidium dimidiatum, Alternaria solani, and Aspergillus niveus achieved a colonization rate of 0.83%. The results of examining the alcoholic extract of the leaves using the HPLC device showed the presence of the chemical compounds aloin at a concentration of 125.39 ppm and aloe emodin at a concentration of 66.59 ppm. We looked at the leaf alcoholic extract with a GC machine and found a group of fatty acids. These included linoleic, oleic, palmitic, and stearic. The GC-MS test revealed a group of active compounds, including Heptane, 1-(ethenylthio), Ethanedicarboxamide, N-allyl-N'-(2,5-dimethylphenyl), 2H-Pyran, 2-(3-butynyloxy) tetrahydro, 1,2-Cyclobutanedicarboxylic acid, 3-methyl-dimethyl ester and 4 (1H)-Pyrimidinone, 2-(propylthio). The presence of endophytic fungi from which effective enzymes or compounds can be isolated could probably have an important role in future medical and therapeutic uses. Also, the leaves of the A. vera plant have medicinal and therapeutic uses for many diseases.

Micorrizas arbusculares em pomares de mangueira no semiárido brasileiro: influência da fenologia, do manejo e da variedade

ABSTRACT: Arbuscular mycorrhizal fungi (AMF) increase the absorption surface of roots, providing greater absorption of water and nutrients from the soil by plants. Thus, it is important to know how arbuscular mycorrhizae are affected by factors such as phenology, management and varieties in mango (Mangifera indica) orchards in the irrigated semi-arid region. With this objective, soil and root samples were collected during the vegetative, flowering and fruiting stages, and in the water stress period before flowering, always on the same trees. The study was carried out in mango orchards of the Keitt and Palmer varieties, in agricultural farms located in Juazeiro - BA and Petrolina - PE, both under conventional management (with fertilizers and paclobutazol). The soil was used to quantify the number of AMF spores and phosphorus content. Mycorrhizal colonization in roots was evaluated in qualitative terms (presence of hyphae, vesicles and arbuscles) and quantitative terms (% of colonization). Total mycorrhizal colonization was high, with averages above 65%, and higher values in the fruiting period. Colonization by vesicles and arbuscles was on average above 45% and 17%, respectively, with higher means also during fruiting. The number of AMF spores in the soil averaged over 130 spores in 50 g of soil, with higher values in the period of water stress. The phosphorus content in the soil did not influence mycorrhizal colonization and the number of spores in the soil. The association of AMF with mango trees was generally affected by management and phenology, regardless of the cultivated varieties.

Effects of mixtures of herbicides on nutrient cycling and plant support considering current agriculture practices

The use of mixtures of pesticides and consecutive pesticide applications challenge current regulations aimed at protecting ecosystem health due to unpredictable effects of complex and dynamic mixtures. In this study, we tested the ecotoxicological effects of mixtures of herbicides, applied following a real application scheme of soybean production on soil health in a mesocosm experiment. The experiment included two sequential applications; first, glyphosate + dicamba + clethodim, and 30 days later, flumioxazin + metolachlor. Commercial products were used at the recommended doses and at two other concentrations: half and double the recommended dose. Soybean plants were exposed to the herbicide-contaminated soil from the time of sowing to the beginning of pod formation. Half of the plants were harvested at the vegetative stage and the remaining plants at the reproductive stage to evaluate endpoints related to plant support and nutrient cycling. Plant biomass was significantly affected during the vegetative stage at the recommended and double the recommended dose, with the effects being mixture-dose dependent. Lower total and arbuscular colonization of mycorrhizas were also observed in double the recommended dose, and intermediate results were observed for the recommended dose. Nodule mass and phosphorous concentration in plants decreased with increasing herbicide doses. By the end of the experiment, nodule mass and total mycorrhizal colonization were low in the plants treated with double the recommended dose of herbicides. However, both endpoints reached similar values to the control at lower herbicide doses. Plant height and phenology were only lower at double the recommended dose during the experiment. The use of non-standard endpoints evidenced that important soil functions were transiently or permanently affected, while the realistic application scheme accounted for the impact of the management practice currently used. Pesticide risk assessment should therefore, incorporate both issues to effectively protect the ecosystems.

Identifying microbiota community patterns important for plant protection using synthetic communities and machine learning

Plant-associated microbiomes contribute to important ecosystem functions such as host resistance to biotic and abiotic stresses. The factors that determine such community outcomes are inherently difficult to identify under complex environmental conditions. In this study, we present an experimental and analytical approach to explore microbiota properties relevant for a microbiota-conferred host phenotype, here plant protection, in a reductionist system. We screened 136 randomly assembled synthetic communities (SynComs) of five bacterial strains each, followed by classification and regression analyses as well as empirical validation to test potential explanatory factors of community structure and composition, including evenness, total commensal colonization, phylogenetic diversity, and strain identity. We find strain identity to be the most important predictor of pathogen reduction, with machine learning algorithms improving performances compared to random classifications (94-100% versus 32% recall) and non-modelled predictions (0.79-1.06 versus 1.5 RMSE). Further experimental validation confirms three strains as the main drivers of pathogen reduction and two additional strains that confer protection in combination. Beyond the specific application presented in our study, we provide a framework that can be adapted to help determine features relevant for microbiota function in other biological systems.

Percolation of ‘civilisation’ in a homogeneous isotropic universe

In this work, we consider the spread of a ‘civilisation’ in an idealised homogeneous isotropic universe where all the planets of interest are habitable. Following a framework that goes beyond the usual idea of percolation in common undergraduate computational physics textbooks, we investigate the behaviour of the number of colonised planets with time, and the total colonisation time for three types of universes. These include static, dark energy-dominated, and matter-dominated universes. For all these types of universes, we find a remarkable fit with the Logistic Growth Function for the number of colonised planets with time. This is in spite of the fact that for the matter- and dark-energy dominated universes, the space itself is expanding. For the total colonisation time, T, the case for a dark energy-dominated universe is marked with divergence beyond the linear regime characterised by small values of the Hubble parameter, H. Not all planets in a spherical section of this universe can be ‘colonised’ due to the presence of a shrinking Hubble sphere. In other words, the recession speeds of other planets go beyond the speed of light making them impossible to reach. On the other hand, for a matter-dominated universe, while there is an apparent horizon, the Hubble sphere is growing instead of shrinking. This leads to a finite total colonisation time that depends on the Hubble parameter characterising the Universe; in particular, we find T ∼ H for small H and T ∼ H 2 for large H.

Epiphytic microflora and mycotoxin content in meadows-Is plant biodiversity affecting fungal contamination?

Ecosystem services are an important aspect of grasslands utilization; however, they are often contradictory to their main purpose, which is a production of good quality and safe feed. In this study, we evaluated the difference between grass monocultures and species-rich mixtures in terms of epiphytic microflora and mycotoxin contamination levels. We hypothesized that higher species diversity would lead to higher microbial counts, which could lead to higher mycotoxin contamination risk. Differences in epiphytic fungal, yeast and total amount of microorganisms (CFU g -1) depending on the species diversity in the field has been evaluated by cultivation method. Concentration of deoxynivalenol (DON), zearalenone (ZEN) and aflatoxin B1 (AFB1) was measured by ELISA. Results are suggesting that higher total amount of microorganisms were found in monocultures, however, fungal and yeast counts were higher in species-rich mixtures. Higher species diversity of grasses was related to higher total microbial count (TMC) and yeast colonization of phyllosphere. Our results suggest higher risk of fungal phyllosphere colonization of species-rich mixtures with higher biodiversity and therefore higher risk of mycotoxin contamination of such feed.

Biochemical characterization and mycorrhizal fungal community of plant species in the Brazilian seasonal dry forest.

Invasive alien plant species (IAPS) have the ability to change the biochemical properties and the arbuscular mycorrhizal fungal (AMF) community structure in their rhizosphere. Organic acids, microbial activity, and AMF play a key role in the invader's spread and also has interactions with the soil chemical factors. Our aim here was to assess the rhizosphere's biochemical factors, AMF community composition, and soil chemical properties associated with Cryptostegia madagascariensis (IAPS) and Mimosa tenuiflora (endemic plant species) from the Brazilian Seasonal Dry Forest. The highest values of total glomalin (5.87 mg g-1 soil), root colonization (54.5%), oxalic and malic acids (84.21 and 3.01 μmol g-1 , respectively), microbial biomass C (mg kg-1 ), Na+ (0.080 cmolc kg-1 ), Ca2+ (7.04 cmolc kg-1 ), and soil organic carbon (4.59 g kg-1 ) were found in the rhizosphere of C. madagascariensis. We found dissimilarities on AMF community structure considering the studied plant species: (i) Racocetra coralloidea, Dentiscutata heterogama, Dentiscutata cerradensis, Gigaspora decipiens, and AMF's richness were highly correlated with the rhizosphere of M. tenuiflora; and (ii). The rhizosphere of C. madagascariensis was highly correlated with the abundance of Claroideoglomus etunicatum, Rhizoglomus aggregatum, Funneliformis mosseae, and Funneliformis geosporum. The results of our study highlight the importance of considering C. madagascariensis as potential hosts for AMF species from Glomerales, and a potential plant species that increase the bioavailability of exchangeable Na and Ca at semi-arid conditions.

Ecotype and fungal endophyte status differentially affect soil arbuscular mycorrhizal community of the native grass Bromus auleticus

In wild native grasses, the colonization of arbuscular mycorrhizal fungi (AMF) is higher in Epichloë-infected plants (E+) compared to Epichloë-free plants (E−). To explore the correlation between the host ecotype, Epichloë association, and the soil AMF community, a common garden experiment was conducted. To achieve this, the soil AMF community of two Bromus auleticus ecotypes, El Palmar (EP) and La Pampa (LP), with either E+ or E−endophyte status, was analyzed using high throughput sequencing. The total mycorrhizal colonization of E+ plants from both EP and LP ecotypes showed significantly higher values (178.68% and 132.34% respectively) compared to E−plants, regardless of the ecotype. Alpha and Beta diversity analysis revealed significant differences in AMF richness and composition between the El Palmar (EP) and La Pampa (LP) ecotypes. However, no differences were observed in the soil AMF communities between E+ and E−plants. In conclusion, this study demonstrates that Epichloë symbiosis and host ecotype have distinct effects on various aspects of the AMF-Bromus auleticus association.

Association between nasopharyngeal colonization with multiple pneumococcal serotypes and total pneumococcal colonization density in young Peruvian children

ObjectivesWe examined the association of nasopharyngeal (NP) pneumococcal co-colonization (>1 pneumococcal serotype) and pneumococcal density in young Peruvian children enrolled in a prospective cohort study. MethodsNP swabs collected monthly from children aged <3 years during both asymptomatic and acute respiratory illness (ARI) periods underwent culture-enriched microarray for pneumococcal detection and serotyping and lytA polymerase chain reaction for density assessment. We examined the serotypes commonly associated with co-colonization and the distribution of densities by co-colonization, age, current ARI, and other covariates. The association of co-colonization and pneumococcal density was assessed using a multivariable mixed-effects linear regression model, accounting for repeated measures and relevant covariates. ResultsA total of 27 children contributed 575 monthly NP samples. Pneumococcus was detected in 302 of 575 (53%) samples, and co-colonization was detected in 61 of these 302 (20%). The total densities were higher during ARI than non-ARI periods and lowest among the youngest children, increasing with age. In the multivariable analysis, there was no significant association between pneumococcal density and co-colonization (coefficient estimate 0.22, 95% confidence interval 0.11-0.55; reference: single-serotype detections). Serotypes 23B and 19F were detected significantly more frequently as single isolates. ConclusionPneumococcal co-colonization was common and not associated with increased pneumococcal density. Differential propensity for co-colonization was observed among individual serotypes.

Occurrence of dark septate endophytes in Phragmites australis in the Baiyang Lake and their resistance to Cd stress

Heavy metal pollution poses a serious hazard to human health, and microbial remediation of heavy metals in soil has been widely studied. A group of ascomycetes classified as dark septate endophytes (DSEs) colonize plant roots and benefit host plants under abiotic stress conditions. In this study, Phragmites australis, a common remediation plant in Baiyang Lake, was investigated. The root system and soil of P. australis were collected in typical heavy metal-contaminated sites, and the species diversity and community structure of DSEs in P. australis roots were studied. In addition, DSE strains were isolated, cultured, and tested for their tolerance to Cd stress. The results showed that DSEs occur extensively in P. australis roots, forming typical dark septate hyphae, with a total colonization rate of 19.7–83.1%. Morphological and ITS sequencing analyses were used to identify 10 DSE fungi in 9 genera. Among these fungi, 6 strains with considerable resistance to Cd stress were identified. The biomass values of Poaceascoma helicoides, Alternaria doliconidium, and Acrocalymma vagum strains increased as the Cd concentration increased. These results can not only help to understand plant-DSE interactions in wetland environments, but also provide a theoretical basis for making full use of DSE fungi to alleviate heavy metals in soil.

Agro-industrial waste based substrate for production of two major cultivated oyster mushrooms in sub-Himalayan West Bengall

Aim: To compare the outcomes of various agro-industrial wastes on the growth, yield and nutritional contents of two major cultivated oyster mushrooms, Pleurotus ostreatus and Pleurotus djamor. Methodology: Locally available agro-industrial wastes were utilized as substrate in five formulations including rice straw alone and in combination with card board (7: 3), waste paper (7: 3), rice husk (17:3) and jack fruit saw dust (7:3). After sterilization substrates were inoculated with mature spawn and placed in cropping room. Results: Total yield, biological efficiency and nutritional contents were found better in the fruiting bodies of Pleurotus ostreatus and Pleurotus djamor cultivated on rice straw as the sole substrate than the mixed substrate formulations. Total colonization period (22.6 days for P. ostreatus and 20.2 days for P. djamor) was quite less for both the oyster mushroom cultivated in rice husk mixed substrate among mixed substrate formulations. Among mixed substrate formulations, highest total yield was obtained from waste paper mixed substrate for Pleurotus ostreatus (713.8 g) and card board mixed substrate for Pleurotus djamor (737.7 g). The highest carbohydrate content in Pleurotus ostreatus and Pleurotus djamor were found in card board mixed substrate. Total protein content was high in fruiting bodies cultivated on saw dust mixed substrate for both the oyster mushrooms. Interpretation: Card board, waste paper, rice husk and saw dust mixed substrates showed relatively high fruiting body yield and nutritional values. It can be concluded that these agro-industrial waste appears to be the promising ingredients in combination with rice straw for cultivation of oyster mushroom. Key words: Agro-Industrial waste, Nutrition, Oyster mushrooms, Pleurotus, Rice straw

Edaphic factors and elevation gradient influence arbuscular mycorrhizal colonization and spore density in the rhizosphere of Shorea robusta Gaertn

Arbuscular mycorrhizal fungi (AMF) are important ecosystem engineers that improve nutrient uptake and help plants adapt to a variety of abiotic stresses. Few studies have examined the relationship between AMF and a specific host tree along an elevation gradient. Shorea robusta is the dominant tree species in Nepal's tropical forests, with very high timber value. The goal of this study was to ascertain how edaphic factors and elevation gradient influence AMF colonization and spore density within the rhizosphere of Shorea robusta. The present study was conducted in four S. robusta dominated forests ranging from 82 m to 950 m asl. Among the four forests, Tarai Sal forest (TSF); Bhabar Sal forest (BSF) belonged to lower elevation Sal forest and Plateau Sal forest (PSF); Hill Sal forest (HSF) belonged to high elevation Sal forest. The percentage of AMF colonization and soil spore density were assessed by magnified intersect method and wet sieving and decanting method respectively. The edaphic factors viz. organic matter, nitrogen, phosphorous, potassium, pH, soil temperature, bulk density, moisture content, and water holding capacity of soil were determined by standard methods. Total AMF colonization ranged from 33% to 57%. Spore density, on the other hand, ranged from 25 to 366 per 100 g of soil. The maximum AMF root colonization and spore density for lower elevation Sal forest was 52% and 39/100 g of soil respectively while that for higher elevation Sal forest was 57% and 366/100 g of soil respectively. Pearson's correlation test revealed that total AMF colonization as well as spore density in the rhizosphere of S. robusta were affected by phosphorus content, pH, moisture content, water-holding capacity, soil temperature, and elevation. Moreover, the spore density was also affected by nitrogen content. Total AMF colonization and spore density were found to be highly correlated. Overall, the intensity of AMF colonization and spore density were higher in higher elevation Sal forest compared to the lower elevation Sal forest. This study can be used to gain insights into the active involvement of AMF in the sustainable management of the forest ecosystem.

Uncovering gut microbiota-mediated indirect effects of antibiotic use on Clostridioides difficile transmission

Background:Clostridioides difficile and multidrug-resistant organisms (MDROs) pose challenges due to treatment complexities and substantial morbidity and mortality. Susceptibility to colonization with these organisms and potential onward transmission if colonized (ie, infectivity) is influenced by the human microbiome and its dynamics. Disruptive effects of antibiotics on the microbiome imply potential indirect effects of antibiotics on C. difficile colonization. Mathematical models can help explore the relative impact of key pathways linking antibiotic use to C. difficile colonization, including the relationship between population-level antibiotic use and colonization prevalence. Methods: We built a compartmental model of long-term C. difficile colonization prevalence of nursing home residents (though malleable for any MDRO), allowing interactions between the microbiome and the colonization process. Based on proportional abundance of microbial taxa, we classified individuals into high and low α diversity groups, each further stratified into uncolonized or colonized with C. difficile. The rate of transition from the high to low microbiome diversity group was proportional to the population-level rate of antibiotic use. Transmission dynamics followed a susceptible–infectious–susceptible framework with the possibility for increased susceptibility and infectivity for the low-diversity microbiome group. First, as a comparator, we used a “null model” in which microbiome diversity did not influence host susceptibility or infectivity. Next, we sampled from realistic (literature informed) parameter ranges to analyze how the microbiome mediates the effect of antibiotics on colonization in this population. Results: Our analysis suggests that antibiotic use can catalyze colonization with C. difficile through interactions with the host microbiome, resulting in a sharp increase in colonization with a modest increase in antibiotic use (Fig 1). Increasing the population-level antibiotic use by 5% led to a median 24% increase in long-term colonization prevalence in the model (Fig 2). In contrast, increasing susceptibility or infectivity rates by 5% resulted in slightly higher increases in total colonization (27% and 29%, respectively). However, there was considerable uncertainty around these estimates, with interquartile ranges of up to 20% for some parameters (Fig 2). Conclusions: Higher population-level antibiotic use likely increases colonization by C. difficile through indirect effects of the microbiome. The increased colonization burden attributable to increasing antibiotic use may be substantial. With high uncertainty around some estimates, conducting observational studies to better understand key colonization and microbiome parameters (eg, the relative increase in susceptibility or infectivity with lower microbiome diversity) is critical for future efforts to estimate the impact of antibiotic use on colonization with C. difficile and MDROs.Disclosures: None

Helicobacter pylori Chronic-Stage Inflammation Undergoes Fluctuations That Are Altered in tlpA Mutants.

Helicobacter pylori colonizes half of the world's population and is responsible for a significant disease burden by causing gastritis, peptic ulcers, and gastric cancer. The development of host inflammation drives these diseases, but there are still open questions in the field about how H. pylori controls this process. We characterized H. pylori inflammation using an 8-month mouse infection time course and comparison of the wild type (WT) and a previously identified mutant lacking the TlpA chemoreceptor that causes elevated inflammation. Our work shows that H. pylori chronic-stage corpus inflammation undergoes surprising fluctuations, with changes in Th17 and eosinophil numbers. The H. pylori tlpA mutant changed the inflammation temporal characteristics, resulting in different inflammation from the wild type at some time points. tlpA mutants have equivalent total and gland colonization in late-stage infections. During early infection, in contrast, they show elevated gland and total colonization compared to those by WT. Our results suggest the chronic inflammation setting is dynamic and may be influenced by colonization properties of early infection.