Fungal Density Research Articles

Influence of environmental conditions on the growth of Pleurotus ostreatus in sand

Pleurotus ostreatus, a saprotrophic fungus, has been proposed for the remediation of organic contaminants in soils and more recently for modifying the hydraulic and mechanical behaviour of granular soils. The in situ performance of fungal-based biotechnologies will be controlled by the fungal growth and associated biochemical activity that can be achieved in soil. In this study, the influence of environmental conditions (temperature, degree of saturation), substrate type (lignocellulose and spent coffee grounds) and concentration on the mycelium growth of P. ostreatus in sand are investigated. Furthermore, the evolution of growth/survival indicators (respiration, ergosterol concentration) and enzymatic activity (laccase, manganese peroxidase) are investigated. Temperature was shown to have a strong influence on the growth of P.ostreatus in sand: growth was observed to be delayed at low temperatures (e.g. 5 °C), whereas growth was prevented at high temperatures (e.g. 35 °C). No growth was observed at very low degrees of saturation (Sr=0% and 1.2%), indicating there is a critical water content required to support P.ostreatus growth. Within the mid-range of water contents tested radially, growth of P.ostreatus was similar. However, growth under saturated soil conditions was restricted to the air-water atmosphere due to the requirement for oxygen availability. Low substrate concentrations (1%–5%) resulted in high radial growth of P.ostreatus, whereas increasing substrate content further acted to reduce radial growth, but visual observations indicated that fungal biomass density increased. These results are important for understanding the feasibility of P.ostreatus growth under specific site conditions and for the design of successful treatment strategies.

Quantitative MRI of a Cerebral Cryptococcoma Mouse Model for In Vivo Distinction between Different Cryptococcal Molecular Types.

The controversially discussed taxonomy of the Cryptococcus neoformans/Cryptococcus gattii species complex encompasses at least eight major molecular types. Cerebral cryptococcomas are a common manifestation of cryptococcal neurological disease. In this study, we compared neurotypical symptoms and differential neurovirulence induced by one representative isolate for each of the eight molecular types studied. We compared single focal lesions caused by the different isolates and evaluated the potential relationships between the fungal burden and properties obtained with quantitative magnetic resonance imaging (qMRI) techniques such as diffusion MRI, T2 relaxometry and magnetic resonance spectroscopy (MRS). We observed an inverse correlation between parametric data and lesion density, and we were able to monitor longitudinally biophysical properties of cryptococcomas induced by different molecular types. Because the MRI/MRS techniques are also clinically available, the same approach could be used to assess image-based biophysical properties that correlate with fungal cell density in lesions in patients to determine personalized treatments.

Application of algal-mycelial pellets in the treatment of the mariculture wastewater

Hypersaline mariculture wastewater necessitates treatment prior to its discharge into marine environments. Algal-mycelial pellets (AMPs), known for their cost-effectiveness, energy efficiency and sustainability, have not been previously explored for their flocculation and pollutant removal capabilities in hyperhaline conditions. This work employed an orthogonal test design to investigate the effects of nine factors at three levels on the treatment efficiency of mariculture wastewater using Chlorella sp. TNBR1 and Aspergillus niger AMPs. The comprehensive optimal conditions for achieving the highest flocculation efficiency and pollutant removal are determined to be a temperature of 30 °C, light intensity of 6000 lux, a 12:0 light-dark cycle, an initial pH of 6, a microalgal density of 11.25 × 106 cell/mL, microalgal growth phase at the early logarithmic stage, a fungal spore density of 9.00 × 105 spore/mL and a fungal pellet phase of 60 h. Under such conditions, the treatment of nonsterile actual mariculture wastewater with Chlorella sp. TNBR1 and Aspergillus niger AMPs results in a 93.35 %±7.20 % reduction in chemical oxygen demand (COD), 92.83 %±7.29 % reduction in total nitrogen (TN), 100 % removal of total phosphorus (TP), and a flocculation efficiency of 69.21 %±5.36 %. These findings confirm that AMPs are a viable solution for effectively treating COD, TN and TP in real hypersaline mariculture wastewater, while also facilitating the flocculation and harvesting of microalgae.

Non-mycorrhizal root-associated fungi increase soil C stocks and stability via diverse mechanisms

Abstract. While various root-associated fungi could facilitate soil carbon (C) storage and therefore aid climate change mitigation, so far research in this area has largely focused on mycorrhizal fungi, and potential impacts and mechanisms for other fungi are largely unknown. Here, with the aim of identifying novel organisms that could be introduced to crop plants to promote C sequestration, we assessed the soil C storage potential of 12 root-associated, non-mycorrhizal fungal isolates (spanning nine genera and selected from a wide pool based on traits potentially linked to soil C accrual) and investigated fungal, plant and microbial mediators. We grew wheat plants inoculated with individual isolates in chambers allowing continuous 13C labelling. After harvest, we quantified C storage potential by measuring pools of different origin (plant vs. soil) and different stability with long-term soil incubations and size/density fractionation. We assessed plant and microbial community responses as well as fungal physiological and morphological traits in a parallel in vitro study. While inoculation with 3 of the 12 isolates resulted in significant total soil C increases, soil C stability improved under inoculation with most isolates – as a result of increases in resistant C pools and decreases in labile pools and respired C. Further, these increases in soil C stability were positively associated with various fungal traits and plant growth responses, including greater fungal hyphal density and plant biomass, indicating multiple direct and indirect mechanisms for fungal impacts on soil C storage. We found more evidence for metabolic inhibition of microbial decomposition than for physical limitation under the fungal treatments. Our study provides the first direct experimental evidence in plant–soil systems that inoculation with specific non-mycorrhizal fungal strains can improve soil C storage, primarily by stabilising existing C. By identifying specific fungi and traits that hold promise for enhancing soil C storage, our study highlights the potential of non-mycorrhizal fungi in C sequestration and the need to study the mechanisms underpinning it.

EFFET DE LORPAILLAGE SUR LABONDANCE ET LA DIVERSITE DES ESPECES DE CHAMPIGNONS MYCORHIZIENS ARBUSCULAIRES DANS LA REGION CENTRALE DU TOGO

Gold mining has a negative impact on the soil include microorganisms such as Arbuscular Mycorrhizal Fungi (AMF). The AMF form associations with plants by improving their development However, the effect of gold mining on Arbuscular Mycorrhizal Fungi (AMF) living in its soils is poorly understood.The objective of this study was to characterize the effect of gold mining on the abundance and diversity of AMF species in the Central region of Togo. The AMF were extracted by wet sieving from 200g of soil samples taken directly from four types of soil, Gold Soil (SA), Washed Gold Soil (SAL), Soil Under Corn Cultivation (SSCM) and the Soil Under Natural Vegetation (SSVN). The diversity of AMF was determined by diversity indices. The results showed that SA, SSCM and SSVN had significantly higher AMF fungal spores densities (p < 0.05) than SAL. AMF species richness was generally lower in SAL (12 species out of a total of 30 species identified). A total of 30 AMF species classified into 16 genera, in 9 families (AcaulosporaceaeAmbisporaceae, Archaeosporaceae, Gigasporaceae, Claroideoglomeraceae, Dentiscutataceae, Diversisporaceae, Glomeraceae, Paraglomeraceae) were identified. The most frequent species were Acaulosporascorbiculata, Acaulospora sp., Entrophosporainfrequens, Gigaspora gigantea, Claroideoglomusetunicatum. The most abundant species were Acaulosporascorbiculata, Acaulosporasp., Entrophosporainfrequens, ClaroideoglomusEtunicatum, Glomus clavisporum, and Rhizophagusintraradices. The biological diversity indices (Shannon and Pielou equitability) revealed a significant difference (P < 0.05) between the different types of soils studied. The density of the spores as well as their diversityvary as follows: SAL<SA< SSVN< SSCM. The soils of the study area contain a great natural wealth of AMF species, but this natural wealth is significantly affected by gold panning. The native AMF found in these areas could be used for the ecological restoration of degraded gold panning areas.

New Immunological Markers in Chromoblastomycosis-The Importance of PD-1 and PD-L1 Molecules in Human Infection.

The pathogenesis of chromoblastomycosis (CBM) is associated with Th2 and/or T regulatory immune responses, while resistance is associated with a Th1 response. However, even in the presence of IFN-γ, fungi persist in the lesions, and the reason for this persistence is unknown. To clarify the factors associated with pathogenesis, this study aimed to determine the polarization of the cellular immune response and the densities of cells that express markers of exhaustion in the skin of CBM patients. In the skin of patients with CBM, a moderate inflammatory infiltrate was observed, characterized primarily by the occurrence of histiocytes. Analysis of fungal density allowed us to divide patients into groups that exhibited low and high fungal densities; however, the intensity of the inflammatory response was not related to mycotic loads. Furthermore, patients with CBM exhibited a significant increase in the number of CD4+ and CD8+ cells associated with a high density of IL-10-, IL-17-, and IFN-γ-producing cells, indicating the presence of a chronic and mixed cellular immune response, which was also independent of fungal load. A significant increase in the number of PD-1+ and PD-L1+ cells was observed, which may be associated with the maintenance of the fungus in the skin and the progression of the disease.

Morphological and ultrastructural changes in fungal agents after LASER application.

Onychomycosis is a fungal nail infection of difficult treatment due to the fungal survival capacity and reduced number of effective therapies. The present study aimed to isolate fungal agents that cause onychomycosis in immunocompetent patients and evaluate how LASER treatments affect the growth and ultrastructure of isolates. In total, 21 patients with positive direct microscopic examination (DME) for onychomycosis had nail samples collected for cultivation and phenotypic identification of microorganisms. From these patients, 12 underwent LASER treatment, divided in Group 1 (n = 5) treated with Nd: YAG 1,064 nm, and Group 2 (n = 7) treated with Nd: YAG 1,064 nm + Er: YAG 2,940 nm + topical isoconazole. Transmission Electron Microscopy (TEM) was performed to evaluate ultrastructural changes after treatment. DME, cultivation, and phenotypic identification showed that the most identified fungus was Trichophyton rubrum spp. After LASER therapy, sample cultivation showed alterations in the fungal morphology with reduction of hyphae, conidia, and reproductive structures. Alterations in fungal cell wall structure, cytoplasm density, and organelles were observed by TEM. LASER irradiation causes changes in the fungal cells, especially in the number of hyphae and the presence of conidia. In addition, it affects fungal growth and reproduction capacity, which interferes with their infection ability and virulence.

Responses of arbuscular mycorrhizal fungal morphological traits and the diversity of spore-associated bacteria to simulated nitrogen deposition and drought in a Cunninghamia lanceolata plantation soil

Arbuscular mycorrhizal (AM) fungi play an important role in plant nutrient absorption and stress resistance. AM fungal spore-associated bacteria are essential for mycorrhizal colonization, but their responses to environmental changes remain largely unknown. We collected surface soil samples from a Chinese fir plantation in both summer and winter to investigate the responses of AM fungal morphological traits and spore-associated bacterial communities to simulated nitrogen deposition (40 kg N·hm-2·a-1 addition) and drought (-50% precipitation exclusion). Our results showed that nitrogen addition and precipitation exclusion significantly affected AM fungal spore density and extraradical hyphal length, respectively. AM fungal intraradical colonization rate, extraradical hyphal length and spore density were significantly differed between the two seasons. Compared to control (no nitrogen addition and no precipitation exclusion treatment), both nitrogen addition and precipitation exclusion significantly reduced spore density in winter, while precipitation exclusion alone and the combined nitrogen addition and precipitation exclusion significantly increased extraradical hyphal length in summer. The dominant spore-associated bacterial phyla were Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, and Planctomycetes. Nitrogen addition and precipitation exclusion did not affect the diversity of spore-associated bacteria. However, the combined nitrogen addition and precipitation exclusion treatment altered the composition of the bacterial community, with significant variations between the two seasons. The spore-associated bacterial diversity was significantly higher and community variability (or turnover) was lower during summer than winter. Soil total nitrogen, nitrate nitrogen and dissolved organic carbon were important factors influencing the bacterial community composition. In all, the effects of nitrogen addition and precipitation exclusion on the morphological traits of AM fungi are seasonally dependent. The combination of nitrogen addition and precipitation exclusion has a significant impact on AM fungal spore-associated bacterial community structure.

Interactions with fungi vary among Tripsacum dactyloides genotypes from across a precipitation gradient.

Plant-associated microbes, specifically fungal endophytes, augment the ability of many grasses to adapt to extreme environmental conditions. Tripsacum dactyloides (Eastern gamagrass) is a perennial, drought-tolerant grass native to the tallgrass prairies of the central USA. The extent to which the microbiome of T. dactyloides contributes to its drought tolerance is unknown. Ninety-seven genotypes of T. dactyloides were collected from native populations across an east-west precipitation gradient in Kansas, Oklahoma and Texas, and then grown together in a common garden for over 20 years. Root and leaf samples were visually examined for fungal density. Because fungal endophytes confer drought-tolerant capabilities to their host plants, we expected to find higher densities of fungal endophytes in plants from western, drier regions, compared to plants from eastern, wetter regions. Results confirmed a negative correlation between endophyte densities in roots and precipitation at the genotype's original location (r = -0.21 P = 0.04). Our analyses reveal that the host genotype's origin along the precipitation gradient predicts the absolute abundance of symbionts in the root, but not the relative abundances of particular organisms or the overall community composition. Overall, these results demonstrate that genetic variation for plant-microbe interactions can reflect historical environment, and reinforce the importance of considering plant genotype in conservation and restoration work in tallgrass prairie ecosystems.

Fungal Diversity and Distribution in the Biodiversity Hotspots of the Western Himalayas

The western Himalayan region is a biodiversity hotspot. Although much of the flora and fauna has been documented, there are very few studies on fungal diversity. We present the statistical analyses of the sample collections from the last 150 years of data in the fungarium of the Forest Research Institute. We found that the host tree species—pine, oak, deodar, and spruce, had very high Shannon diversity (SD) and species richness (SR), while Dalbergia and Rhododendron had moderate to low SD and SR values; although sal occurs at lower altitudes, it has high SD and SR values. Among fungal families, the highest SD and SR value was found in Polyporaceae. Hymenochaetaceae, Peniophoraceae, Coleosporiaceae, and Stereaceae also showed SD with moderate SR. Fomitopsidaceae, Cronartiaceae, Ganodermataceae, and Thelephoraceae have low biodiversity and species. Thelephoraceae are distributed above 2000 m altitude, and Ganodermataceae and Hymenochaetaceae have wider distribution ranges, namely, 0–3500 m and 0–5000 m, respectively. The Polyporaceae show diverse variations in species distribution and occur between 0 and 4500 m; Coleosporiaceae and Cronartiaceae around 2000 m; Stereaceae, Meruliaceae, Peniophoraceae, and Fomitopsidaceae occur between 1700 and 1800 m, with all Stereaceae and Fomitopsidaceae having different distribution ranges of up to 5000 m. We found that areas with relatively low rainfall had lower species richness, and vice versa, and that high solar radiation negatively affected fungal density and SR, as observed in the distribution of Thelephoraceae. While families with high SD and SR values such as Polyporaceae were found under relatively high rainfall, moderate solar radiation, and high temperatures. Similar studies need to be undertaken in other parts of the Himalayas and the importance of fungi in ethnobotany needs to be understood to ensure sustainable use.

Fungal Density in Lobomycosis in French Guiana: A Proposal for a New Clinico-Histological and Therapeutic Classification.

Lobomycosis is a rare cutaneous tropical neglected disease caused by the fungal agent Lacazia loboi, recently renamed Paracoccidioides lobogeorgii. Our objectives were to present all cases of lobomycosis diagnosed in French Guiana, to offer a precise description of their histopathological features and to propose a new clinico-histological prognostic classification. All cases of lobomycosis diagnosed in French Guiana between 1959 and 2022 were included. We looked for associations between the occurrence of relapses and the clinic-histological form. 31 patients diagnosed with lobomycosis were included. An epidemiological shift was observed in the 2000s as Brazilian patients became the most important ethnic group. Gold mining, forestry and fishing/sailing were reported as professional exposures. New histological features, such as inflammatory "rosettes" formations were described. We describe two clinic-histological patterns: a major form (high fungal density and/or multifocal lesions) and a minor form (low fungal density, unifocal lesions, association with fewer relapses). The changing epidemiology of lobomycosis in French Guiana is characterized by a shift towards Brazilian patients, mostly gold miners. Minor forms should be treated with surgery, major forms with a combination of surgery followed by nultiple drug therapy (MDT) or posaconazole.

Biogeographical patterns of the soil fungal:bacterial ratio across France.

Soils are one of the major reservoirs of biological diversity on our planet because they host a huge richness of microorganisms. The fungal:bacterial (F:B) ratio targets two major functional groups of organisms in soils and can improve our understanding of their importance and efficiency for soil functioning. To better decipher the variability of this ratio and rank the environmental parameters involved, we used the French Soil Quality Monitoring Network (RMQS)-one of the most extensive and a priori-free soil sampling surveys, based on a systematic 16 km × 16 km grid and including more than 2,100 samples. F:B ratios, measured by quantitative PCR targeting the 18S and 16S rDNA genes, turned out to be heterogenously distributed and spatially structured in geographical patterns across France. These distribution patterns differed from bacterial or fungal densities taken separately, supporting the hypothesis that the F:B ratio is not the mere addition of each density but rather results from the complex interactions of the two functional groups. The F:B ratios were mainly influenced by soil characteristics and land management. Among soil characteristics, the pH and, to a lesser extent, the organic carbon content and the carbon:nitrogen (C:N) ratio were the main drivers. These results improved our understanding of soil microbial communities, and from an operational point of view, they suggested that the F:B ratio should be a useful new bioindicator of soil status. The resulting dataset can be considered as a first step toward building up a robust repository essential to any bioindicator and aimed at guiding and helping decision making. IMPORTANCE In the face of human disturbances, microbial activity can be impacted and, e.g., can result in the release of large amounts of soil carbon into the atmosphere, with global impacts on temperature. Therefore, the development and the regular use of soil bioindicators are essential to (i) improve our knowledge of soil microbial communities and (ii) guide and help decision makers define suitable soil management strategies. Bacterial and fungal communities are key players in soil organic matter turnover, but with distinct physiological and ecological characteristics. The fungal:bacterial ratio targets these two major functional groups by investigating their presence and their equilibrium. The aim of our study is to characterize this ratio at a territorial scale and rank the environmental parameters involved so as to further develop a robust repository essential to the interpretation of any bioindicator of soil quality.

Biological Control of Three Fungal Diseases in Strawberry (Fragaria × ananassa) with Arbuscular Mycorrhizal Fungi

Similar to many other plant-based products, strawberries are susceptible to fungal diseases caused by various pathogen groups. In recent years, efforts have been made to combat these diseases using biological control methods, particularly the application of arbuscular mycorrhizal fungi (AMF). This study aimed to determine the effects of AMF (Funneliformis mosseae (Fm) and Gigaspora margarita (Gm)) on Rhizoctonia fragariae (Rf), Fusarium oxysporum (Fo), and Alternaria alternata (Aa), which are major pathogens for strawberry. The results showed that the effects of AMF on disease severity and plant growth varied depending on the pathogens involved. Rf caused the highest disease severity, followed by Fo and Aa, but all AMF treatments significantly reduced the disease severity compared to control treatments. The study also found that the specific AMF species and their combinations influenced plant growth responses under different pathogenic conditions. Different AMF treatments resulted in varying increases in plant fresh weight, dry weight, and length, depending on the pathogen. Moreover, the application of AMF led to increased levels of total phenolic content, antioxidant activity, and phosphorus content in pathogen-infected plants compared to control treatments. Fm was more efficient than Gm in increasing these biochemical parameters. The levels of root colonization by AMF were similar among different AMF treatments, but the effects on fungal spore density varied depending on the pathogen. Some AMF treatments increased fungal spore density, while others did not show significant differences. In conclusion, our research sheds light on the differential effects of AMF species on disease severity, plant growth, and biochemical parameters in strawberry plants facing diverse pathogens. These findings underscore the potential benefits of AMF in disease management, as they reduce disease severity and bolster plant growth and defense mechanisms.

Evaluation of Trichoderma spp. on Fusarium oxysporum f. sp. asparagi and Fusarium wilt Control in Asparagus Crop.

Among the key diseases affecting the asparagus crop (Asparagus officinalis L.), vascular wilting of asparagus caused by Fusarium oxysporum f. sp. asparagi stands out worldwide. This disease significantly shortens the longevity of the crop and limits economic production. Traditional control measures have been largely ineffective, and chemical control methods are difficult to apply, making biological control approaches, specifically the use of Trichoderma, an economical, effective, and risk-free alternative. This study aimed to identify the main factors that affect the efficacy of biopesticides studied as Biological Control Agents (BCAs) against Fusarium wilt in asparagus and to assess the efficacy of Trichoderma-based biopesticides under greenhouse and semi-field conditions. We evaluated the response of three Trichoderma spp. (T. atroviride, T. asperellum, and T. saturnisporum) to environmental variables, such as temperature and water activity, and their antagonistic capacity against Fusarium oxysporum f. sp. asparagi. All three Trichoderma species inhibited the growth of the pathogen in vitro. A decrease in water activity led to a greater reduction in the growth rate. The efficacy of the three biological control agents decreased with higher temperatures, resulting in minimal inhibition, particularly under conditions of restricted available water in the environment. The effect of the fungal inoculum density was also analyzed at two different temperatures. A direct correlation between the amount of inoculum and the score on the Disease Severity Index (DSI) was observed. A notable reduction in DSI was evident in treatments with high inoculum density (106 conidium/mL) for all three species of Trichoderma tested at both temperatures. In greenhouse and semi-field tests, we observed less disease control than expected, although T. asperellum and T. atroviride showed lower disease severity indices and increased the dry weight of seedlings and crowns, whereas T. saturnisporum resulted in the highest disease rate and lowest dry weight. This work highlights that the efficacy of Trichoderma as BCAs is influenced by various factors, including the quantity of soil inocula, and environmental conditions. The study findings have strong implications for selecting appropriate Trichoderma species for controlling specific pathogens under specific environmental conditions.

Co-culture between Miscanthus x giganteus and Trifolium repens L. to enhance microbial activity, biomass and density in a PAH contaminated technosol

Phytoremediation is a biological soil remediation technique using plants and their associated microorganisms to clean-up contaminated soils and improve soils’ quality. We tested whether a co-culture between Miscanthus x giganteus (MxG) and Trifolium repens L. would enhance the soil biological quality. The objective was to determine the influence of MxG in mono- and in co-culture with white clover on the soil microbial activity, biomass and density. MxG was tested in mono- and in co-culture with white clover in a mesocosm over 148 days. The microbial respiration (CO2 production), the microbial biomass and the microbial density of the technosol were measured. Results showed that MxG induced an increase in microbial activity in the technosol compared to the non-planted condition with the co-culture having a greater impact. Regarding the bacterial density, MxG in mono- and in co-culture significantly increased the 16S rDNA gene copy number. The co-culture increased the microbial biomass, the fungal density and stimulated the degrading bacterial population, contrary to the monoculture and the non-planted condition. We can conclude the co-culture between MxG and white clover was more interesting than MxG monoculture in regards to the technosol biological quality and its potential for PAH remediation improvement.

Leaf Species-Dependent Fungicide Effects on the Function and Abundance of Associated Microbial Communities

Microbially-mediated leaf litter decomposition is a critical ecosystem function in running waters within forested areas, which can be affected by fungicides. However, fungicide effects on leaf litter decomposition have been investigated almost exclusively with black alder leaves, a leaf species with traits favourable to consumers (i.e., low recalcitrance and high nutrient content). At the same time, little is known about fungicide effects on microbial colonisation and decomposition of other leaf species with less favourable traits. In this 21 day lasting study, we explore the effects of increasing fungicide sum concentrations (0–3000 µg/L) on microbial colonisation and decomposition of three leaf species (black alder, Norway maple and European beech) differing in terms of recalcitrance and nutrient content. Leaf litter decomposition rate, leaf-associated fungal biomass and bacterial density were quantified to observe potential effects at the functional level. Beech, as the species with the least favourable leaf traits, showed a substantially lower decomposition rate (50%) in absence of fungicides than alder and maple. In the presence of high fungicide concentrations (300–3000 µg/L), beech showed a concentration-related decrease not only in microbial leaf litter decomposition but also fungal biomass. This suggests that favourable traits of leaf litter (as for alder and maple) enable leaf-associated microorganisms to acquire leaf-bound energy more easily to withstand potential effects induced by fungicide exposure. Our results indicate the need to deepen our understanding on how leaf species’ traits interact with the impact of chemical stressors on the leaf decomposition activity of microbial communities.

In vivo assessment of differences in fungal cell density in cerebral cryptococcomas of mice infected with Cryptococcus neoformans or Cryptococcus gattii

In cerebral cryptococcomas caused by Cryptococcus neoformans or Cryptococcus gattii, the density of fungal cells within lesions can contribute to the overall brain fungal burden. In cultures, cell density is inversely related to the size of the cryptococcal capsule, a dynamic polysaccharide layer surrounding the cell. Methods to investigate cell density or related capsule size within fungal lesions of a living host are currently unavailable, precluding in vivo studies on longitudinal changes. Here, we assessed whether intravital microscopy and quantitative magnetic resonance imaging techniques (diffusion MRI and MR relaxometry) would enable non-invasive investigation of fungal cell density in cerebral cryptococcomas in mice. We compared lesions caused by type strains C. neoformans H99 and C. gattii R265 and evaluated potential relations between observed imaging properties, fungal cell density, total cell and capsule size. The observed inverse correlation between apparent diffusion coefficient and cell density permitted longitudinal investigation of cell density changes. Using these imaging methods, we were able to study the multicellular organization and cell density within brain cryptococcomas in the intact host environment of living mice. Since the MRI techniques are also clinically available, the same approach could be used to assess fungal cell density in brain lesions of patients.

ACTIVITES ANTIFONGIQUE ET ANTIBACTERIENNE DES EXTRAITS DE FEUILLES DESTYLOSANTHES ERECTABEAU

During this work, phytochemical analyzes were carried out on the powder of the leaves of Stylosanthes erecta P. Beauv., as well as qualitative analyzes by thin layer chromatography(TLC) and evaluations. The antifungal and the antibacterial activities of the aqueous extracts were made respectively by the diffusion method and by the dilution method.The TLC revealed the spots including gallic tannins, catechism tannins and flavonoids.The antifungal activity against Candida albicans is proportional to the increase in the concentration of the extracts of total tannins. Concentrations of 1000 µg/mL and 1500 µg/mL showed complete inhibition of fungal density. Maceration extracts have more antifungal activity than decoction ones. As for the antibacterial activity, Streptococcus ss and N. gonorrhea were more sensitive to thecrude and tannin extracts than flavonoids ones. The largest inhibition diameters were 15 ± 0.05 mm and 16 ± 0.04 mm on clinical strains. S. typhi was more sensitive to flavonoid extracts. The minimum inhibitory concentration was around 0.5 mg / mL on E. coli, S. typhi, Streptococcus and N. gonorrhea.

Clomazone impact on fungal network complexity and stability.

Soil fungal network composition and stability are important for soil functions, but there is less understanding of the impact of clomazone on network complexity and stability. In this work, two agricultural soils were used to investigate the impact of clomazone on fungal network complexity, composition, and stability. The two soils were treated with clomazone solution (0, 0.8, 8, and 80 mg kg-1) and kept in an incubator. Under the influence of clomazone, the fungal network nodes were decreased by 12-42; however, the average degree was increased by 0.169-1.468 and fungal network density was increased by 0.003-0.054. The keystone nodes were significantly changed after clomazone treatment. Network composition was also impacted. Specifically, compared with control and clomazone treatments in both soils, the shared edges were fewer than 54 in all comparisons, and network dissimilarity was 0.97-0.98. These results suggested that fungal network composition was significantly impacted. The network robustness was increased by 0.0018-0.0209, and vulnerability was decreased by 0.00018-0.00059 in both soils, which indicated that fungal network stability was increased by clomazone. In addition, the functions of network communities were also changed in both soils. These results indicated that clomazone could significantly impact soil fungal networks.

Increasing the Biostability of Concrete by the Introduction Of Additives

To increase the resistance to fungal corrosion and improve the performance of concrete cement stone, it is proposed to introduce calcium stearate and active metal nitrates in an amount of 0.5% by weight of cement into the cement mixture at the manufacturing stage. To determine the degree of corrosion damage of cement stone by fungal microorganisms Aspergillus niger, porosity, density, water absorption and strength were determined. It has been found that the introduction of a hydrophobic additive of calcium stearate into the cement mixture during the manufacture of concrete reduces water absorption, reduces porosity and increases strength. Additives of nitrates of active metals do not affect the characteristics of the cement stone of concrete. As a result of 6 months of fungal corrosion, the water absorption, porosity and density of cement stone containing calcium stearate did not change, and the strength decreased by 4%. Metal nitrates do not prevent damage to the cement stone by microorganisms, but slow down the flow of aggressive substances to the surface of the reinforcement in concrete. The combined introduction of calcium stearate and nitrates into the cement mixture will improve the characteristics of concrete, increase its corrosion resistance and ensure the safety of reinforcement in concrete.