Search

Direct planting systems offer several benefits to the soil and plants, as reflected in soil organisms. The Arbuscular mycorrhizal fungi are extremely sensitive to environmental changes and can be used as indicators of soil quality. This study focused on the native diversity of mycorrhizae in the region. Thus, the objective of this work was to evaluate mycorrhizal colonization, spore density, soil glomalin content and species diversity in five wheat genotypes under direct and conventional planting systems. This work was carried out in the experimental area of Embrapa Cerrados, Planaltina, DF, Brazil. The rates of mycorrhizal colonization, spore density and easily extractable glomalin were evaluated, and species of arbuscular mycorrhizal fungi were identified in five wheat genotypes under direct and conventional planting. For all the genotypes under conventional planting, there was a decrease in mycorrhizal colonization, the number of spores in the rhizosphere and the amount of easily extractable glomalin. The composition of the arbuscular mycorrhizal fungal community differed among the wheat genotypes and management systems. The richness of morphospecies of AMF in the direct planting system was similar to that in the conventional system, with twelve species each, but the conventional system reduced root colonization and spore density. The most common species were A. scrobiculata, Si. tortuosum and G. macrocarpum, which were found in all the genotypes in both cultivation systems., (© 2024. The Author(s).)

Organic production systems are increasingly gaining market share; however, there are still few studies on their influence on the activity of soil microorganisms in sugarcane. Arbuscular mycorrhizal fungi are extremely sensitive to environmental changes, and their activity can be used as a parameter of comparison and quality between organic and conventional systems. The objective of this work was to evaluate mycorrhizal activity in different varieties of sugarcane under two production systems. This work was carried out in a commercial plantation of the Jalles Machado plant in the municipality of Goianésia in Goiás, Brazil. The values of spore density in the soil, mycorrhizal colonization rate in the roots and easily extractable glomalin were evaluated, and the associated fungal species were identified. There was no effect of sugarcane variety on the number of spores or the glomalin content in the soil. The conventional system presented significantly lower mycorrhizal colonization rates than did the organic system. The varieties cultivated under the conventional planting system showed a greater diversity of arbuscular mycorrhizal fungi, where 12 of the 13 different species of mycorrhizal fungi found in both cultivation systems occurred., (© 2024. The Author(s).)

Recently, Trichosporon taxonomy has been reevaluated and new genera of the Trichosporonaceae family have been described. Here, 26 clinical isolates were submitted for identification via sequencing of the intergenic space 1 (IGS1) region, genotyping, and investigation of virulence factors. Antifungal susceptibility was determined using the CLSI broth microdilution method for fluconazole (FLC), itraconazole (ITC), and amphotericin B (AMB). Of these, 24 isolates were identified, including 12 T. asahii, 4 T. inkin, 3 T. faecale, 1 T. coremiiforme, 1 T. japonicum, 2 Cutaneotrichosporon dermatis (formerly T. dermatis), and 1 Apiotrichum mycotoxinivorans (formerly T. mycotoxinivorans). Species-level identification of 2 isolates was not successful; they were described as Trichosporon sp. We observed optimal colonial development at 35-40 °C. Lipase was the major extracellular enzyme produced (100%); caseinase was not produced (0%). Biofilms were produced by all isolates (classified as low). High AMB minimum inhibitory concentration (MIC) was observed, with all strains resistant. Fluconazole was the most active drug among the antifungals tested. However, high MICs for FLC were observed in C. dermatis and A. mycotoxinivorans species, which also showed resistance to ITC and AMB. This study, conducted in the Northern region of Brazil, identified 5 Trichosporon species along with C. dermatis and A. mycotoxinivorans and demonstrated their pathogenic potential through their ability to produce important virulence factors. This may contribute to our understanding of the epidemiology and factors related to the pathogeneses of species in the Trichosporonaceae family.

This study aimed to estimate the prevalence of paracoccidioidal infection by intradermal reaction (Delayed-Type Hypersensitivity, DTH) to Paracoccidioides brasiliensis in rural areas in Alfenas, Southern Minas Gerais (MG) State, Brazil, and to assess risk factors (gender, occupation, age, alcohol intake and smoking) associated with infection. We conducted a population-based cross-sectional study using intradermal tests with gp 43 paracoccidioidin in 542 participants, who were previously contacted by local health agents and so spontaneously attended the test. Participants underwent an interview by filling out a registration form with epidemiological data and were tested with an intradermal administration of 0.1 mL of paracoccidioidin in the left forearm. The test was read 48 hours after injection and was considered positive if induration was greater than or equal to 5 mm. Out of 542 participants, 46.67% were positive to the skin test. Prevalence increased in accordance with an increase of age. There was statistical significance only for males. Occupation, alcohol intake and smoking habits were not significantly associated with the risk of paracoccidioidomycosis infection. There is relevance of paracoccidioidomycosis infection in such rural areas, which suggests that further epidemiological and clinical studies on this mycosis should be done in the southern part of Minas Gerais State.

Epidemiological studies of paracoccidioidomycosis have been based on surveys achieved with intradermal tests, and paracoccidioidin is the most common antigen used in most cases. The glycoprotein of 43-kDa (gp43) has been used in intradermal tests. It is the most antigenic component of Paracoccidioides brasiliensis, and it provides greater specificity to evaluate infection for this fungus. In this study, the prevalence of P. brasiliensis infection was estimated with intradermal tests involving gp43 for 695 people in rural Central-West Brazil. The infection rate was 45.8 % (95 % CI = 42.1-49.5), and the average age of those infected was 45.8 ± 18.2 years. The prevalence did not show gender-based differences but increased with age. The results demonstrate the importance of P. brasiliensis infection in rural settlements and the early exposure of children in the region to the fungus. Despite the high antigenicity and specificity of gp43, its usage must be standardized, so that epidemiological surveys will be comparable and more accurately reflect P. brasiliensis infection in endemic areas.

The increasing resistance of Rhipicephalus (Boophilus) microplus tick to commercial insecticides requires alternative methods for the control of this cattle plague. The enthomopathogenic fungus Beauveria felina produces destruxins in culture media, cyclic depsipeptides which display an array of biological activities. The present investigation aimed to evaluate the acaricide action of destruxins isolated from B. felina culture media on R. (B.) microplus engorged females. B. felina was grown in MF medium under 19 different growth conditions. HPLC-PDA analysis of chromatographic fractions obtained from the 19 different growth media extracts indicated the presence of destruxins in all lipophylic fractions. Such fractions were combined and subjected to separation by HPLC. Fractions containing distinct destruxins composition were tested against R. (B.) microplus. Two fractions, composed of destruxin Ed(1) and pseudodestruxin B and/or pseudodestruxin C (fraction P1) as well as by hydroxyhomodestruxin B and/or destruxin D and/or roseotoxin C (fraction P7), displayed 30% and 28.7% acaricidal efficacy, respectively. This activity profile in such low concentration is adequate to consider destruxins as potential leading compounds to be developed for tick biological control., (Copyright © 2012 Elsevier Inc. All rights reserved.)

An epidemiological survey was performed in 118 workers from northwestern Paraná state using gp43 as antigen, the positivity was 43%. This result, plus the weather conditions, which are favorable for fungus development, underscores that this region is an endemic area for paracoccidioidomycosis and is a reservoir of Paracoccidioides brasiliensis.

In a survey for primary paracoccidioidomycosis (PCM) infection (and not the clinical disease), two groups of blood donors were analyzed. One study group was drawn from donors living in a rural area where PCM is endemic, and the other group from urban residents of a large city, São Paulo. Anti-Paracoccidioides brasiliensis (Pb) specific antibodies (IgG) in sera were analyzed by ELISA, using crude Pb exoantigens (exoAg) and purified specific Pb 43 kDa glycoprotein (gp43). The results showed that 21% of 700 rural samples and 0.9% of 350 urban samples were positive for exoAg and gp43. To avoid cross-reactions, the sera were adsorbed first with Histoplasma capsulatum antigens and secondly with Leishmania amazonensis antigens. In the first adsorption with H. capsulatum, reactivity to gp43 fell to 12.8% in the rural group and to 0% in the urban group. In the succeeding adsorption with L. amazonensis, this reactivity fell to 12.3% in the rural group. There was a statistically greater proportion of persons with gp43-reactive antibodies in rural group than in the urban group, indicating that rural residents had frequently become exposed to Pb and contracted primary, subclinical PCM. The present report is the first epidemiological study using ELISA to detect antibodies against gp43 in blood donors.

We report here the results obtained in epidemiologic surveys of histoplasmosis and paracoccidioidomycosis carried out in Brazil using the histoplasmin and paracoccidioidin delayed hypersensitivity skin tests. Most of these data have not been previously published in scientific journals and are now reported here in two tables respectively concerning histoplasmosis (88 surveys) and paracoccidioidomycosis (58 surveys). The guidelines to be followed in surveys of this nature are also commented upon.

Skin tests with paracoccidioidin, histoplasmin and sporotrichin were applied to 417 workers of Morro Velho Mining in the State of Minas Gerais, Brazil, with the main purpose of detecting the prevalence of paracoccidioidomycosis-infection, histoplasmosis capsulate-infection and sporotrichosis-infection. The rates of positivity to the skin tests were 13.43% for paracoccidioidin, 17.50% for histoplasmin and 13.67% for sporotrichin. Several epidemiological factors were investigated for a better interpretation of the results. Paracoccidioides brasiliensis, Histoplasma capsulatum var. capsulatum and Sporothrix schenkii were not isolated from the soil samples from the mines investigated.

Paracoccidioidin and histoplasmin intradermic tests were performed in 107 inhabitants in Arapiraca, Alagoas. The epidemiological survey was performed in both sexes and the ages varied from 2 to 71 years. Positive results with paracoccidioidin test were recorded in 11% and the histoplasmin test was positive in 14%. With the positivity of paracoccidioidin in the histoplasmin positive population the result shows a percentage of 33.33%, while with the positivity of histoplasmin in the paracoccidioidin positive population was 41%.

Intradermal tests using histoplasmin and paracoccidioidin antigens were performed in 138 persons from Pereiro, Ceará, Brazil. The results were positive in 61.5% and 32.5% with histoplasmin and paracoccidioidin antigens respectively. These results suggest infection by H. capsulatum and P. brasiliensis in the people living in the studied area. New studies are necessary to detect histoplasmosis and paracoccidioidomycosis as clinical diseases in that region.