Total Number Of Spores Research Articles

The effectiveness of arbuscular mycorrhizal fungal species (Funneliformis mosseae, Rhizophagus intraradices, and Claroideoglomus etunicatum) in the biocontrol of root and crown rot pathogens, Fusarium solani and Fusarium mixture in pepper.

This study evaluated the effectiveness of arbuscular mycorrhizal fungi (AMF) species, including Funneliformis mosseae (FM), Rhizophagus intraradices (RI), Claroideoglomus etunicatum (CE), and a Mycorrhizal mix (MM) comprising these three species, on pepper plants (Capsicum annuum L.) inoculated with two isolates of Fusarium solani (48-F. solani and 18-F. solani) and two isolates of Fusarium mix (50-F. mixture and 147-F. mixture). Analysis of variance (ANOVA)-Tukey statistics revealed that the effects of AMF inoculations on morphological parameters, disease severity, root colonization, and total spore numbers in pathogen-infected plants varied significantly depending on the AMF species and pathogen group. AMF colonization significantly reduced disease severity, with disease inhibition (DI) reaching up to 58%, depending on the specific pathogen. However, there were a few instances where the application of AMF did not lead to a reduction in disease severity. Single AMF species were more effective in enhancing the growth of pathogen-treated host plants and suppressing disease compared to the mixed AMF. The mixed AMF was only more effective in balancing pathogen-induced decreases in plant nutrients (Copper (Cu), Magnesium (Mg), Zinc (Zn), and Phosphorus (P)). Among the compared mycorrhizae, C. etunicatum (CE) was the most effective in disease suppression due to its relatively more positive effects on plant root structure, increasing root fresh weight by up to 49% in the CE+pathogen plant group compared to the control group. Root colonization rates were generally higher in plants treated with both mycorrhiza and pathogens compared to plants treated with mycorrhiza alone. Overall, the curative effects of AMFs on plants following pathogen application varied concurrently with disease severity rates caused primarily by pathogens. AMFs demonstrated greater efficacy in combating 18-F. solani, which causes less severe plant disease. However, the effectiveness of AMFs was comparatively lower against 48-F. solani and 147-F. mix., which cause more severe plant disease. This indicates that the efficacy of AMFs varies depending on the specific strain of Fusarium solani, with better results observed against strains that cause less severe plant disease.

Способ улучшения зоогигиенических условий выращивания цыплят-бройлеров

Abstract. The purpose of the study is to study the effect of bedding material on the physiological parameters of broiler chickens. Since the most important condition for optimizing the microclimate in the poultry house is compliance with the physiological state of the livestock and maintaining its vital activity at an optimal level. Research methods. The experiment was carried out in the industrial conditions of a poultry farm on broiler stock of the Arbor Acres+ cross in the experimental workshop, where four sections were formed. The growth and development of broilers was monitored daily, livestock records were carried out, and a weekly veterinary report was compiled on the causes of mortality. Also, laboratory studies were carried out according to approved methods for the following indicators: ammonia content, sanitary and hygienic indicators of bedding material, volume, weight and moisture content of bedding material, as well as productivity and basic blood parameters of broiler chickens. Results. Trends in the positive effect of the sorbent in the form of modified diatomite on the productivity of broiler chickens due to the improvement of zoohygienic growing conditions have been identified. In particular, the content of the total number of microorganisms, mold spores and ammonia content in the production experimental workshop is examined in detail. During the work, the volume and weight of bedding material was calculated, including at the exit from the poultry house. We tried to pay special attention to blood biochemistry, which made it possible to assess the physiological state of broiler chickens and draw conclusions about the quality of feeding rations. At the same time, problematic issues associated with feeding poultry were identified, which affect the content of mineral elements in the blood. When determining the performance criterion, calculations were carried out using the EPEF index. Scientific novelty. For the first time, it was proven that the use of diatomite with a bulk layer height of 0.5–1 cm with a granule size of at least 5 mm as bedding material leads to improved zoohygienic conditions for raising broiler chickens without additional capital investments in the form of installation of expensive ventilation equipment or the use of additional technological operations. This replacement option has a positive effect on the health of young poultry.

Effects of cold plasma on the growth and aflatoxin production of Aspergillus flavus

Cold plasma (CP) has an inactivating effect on bacteria, but little research has been done on fungi, especially on aflatoxin (AF)-producing strains of Aspergillus flavus (A. flavus). In this study, a CP device was utilized to investigate the destructive effects and mechanisms of different voltage treatments on AF-producing A. flavus strains. The inactivation curve was fitted using Weibull and Logistics kinetic models (R2 > 0.930). The results of viable spore count and AF detection showed that after 6 min of 60 V treatment, the total number of viable spores decreased by 4.47 log10 CFU/mL, and the AF level was found to be significantly lower after treatment (p < 0.05). The microstructure of A. flavus spores was severely damaged after DBDP treatment. The leakage of nucleic acids and proteins, lipid oxidation level, reactive oxygen level, and Fourier transform infrared spectroscopy analysis of spores all confirmed that the cell membrane of A. flavus was damaged after DBDP treatment. This study could provide reference methods for CP technology in the control of AF-producing A. flavus.

Irrigation Targeted to Provoke Ejection of Ascospores of Venturia inaequalis Shortens the Season for Ascospore Release and Results in Less Apple Scab.

Trials were carried out in apple orchards of Emilia-Romagna and Trentino-Alto Adige in northern Italy to investigate the effects of sprinkler irrigation on possible reduction in inoculum and subsequent disease pressure of Venturia inaequalis, the ascomycete causing apple scab. In spring, volumetric spore traps were placed above apple leaf litter containing pseudothecia with ascospores of the fungus. Pseudothecia matured more rapidly in irrigated plots, and 95% of the total number of spores trapped in a season was reached on average 164 degree days (base temperature 0°C) earlier in irrigated compared with nonirrigated plots. On average for seven location/year combinations, more than 50% of the ascospores were trapped following irrigations carried out for 2 h on sunny days before a forecasted rainfall. Subsequently, a much lower number of spores were trapped on rainy days following irrigation. Field trials with scab-susceptible apple cultivars were carried out in the two regions to evaluate the efficacy of sprinkler irrigation on disease. Irrigated and nonirrigated plots were either treated with different fungicide control strategies or not treated. Irrigation significantly reduced the incidence of apple scab at both sites, and the overall number of infected leaves and fruit was reduced by more than 50%. Midday sprinkler irrigation can significantly reduce the inoculum pressure of V. inaequalis in apple orchards. This may be a sustainable management strategy, especially in areas with extended dry periods.

Changes in the Recovery Efficiency, Nutritional and Safety Quality of Dried Sergestid Shrimp (Acetes species) during Commercial Production

The sun-dried method is popular for producing dried Sergestid shrimp in Vietnam, but maintaining consistent product quality across seasons is challenging due to its dependence on weather conditions. A previous study used convection drying at a laboratory scale. In this study, the laboratory scale was upgraded to a commercial scale, and recovery efficiency and Sergestid shrimp images were recorded during production stages. Parameters were adjusted for economic efficiency and convenience. Results showed a decrease in recovery efficiency on the laboratory scale, while the commercial scale improved with washing and blanching. Overall, there was no significant difference in recovery efficiency between the commercial production (15.76 %) and laboratory scale (16.29 %). The commercial-scale dried Sergestid shrimp exhibited better colour than the laboratory-scale product. The product met food safety and quality criteria according to Vietnamese standards. Microorganisms such as Coliforms, E. coli, B. cereus, C. perfringens and salmonella, and total number of yeast and mold spores, were not detected in the product. On the other hand, the product of commercial production contained 256 kcal 100 g−1 of energy and a protein content of 55.50 ± 0.33 %. These findings form a foundation for scaling up production and assessing economic feasibility. Adjusting production parameters using larger equipment contributes to achieving optimal production efficiency and economic benefits.

Effects of indoor air quality and home environmental characteristics on allergic diseases among preschool children in the Greater Taipei Area

Indoor air quality and home environmental characteristics are potential factors associated with the onset and exacerbation of allergic diseases. Our study examined the effects of these factors on allergic diseases (i.e., asthma, allergic rhinitis, allergic conjunctivitis, and atopic dermatitis) among preschool children. We recruited a total of 120 preschool children from an ongoing birth cohort study in the Greater Taipei Area. A comprehensive environmental evaluation was conducted at each participant's residence and included measurements of indoor and outdoor air pollutants, fungal spores, endotoxins, and house dust mite allergens. A structured questionnaire was used to collect information on the allergic diseases and home environments of participants. Land-use characteristics and points of interest in the surrounding area of each home were analyzed. Other covariates were obtained from the cohort data. Multiple logistic regressions were used to examine the relationships between allergic diseases and covariates. We observed that all mean indoor air pollutant levels were below Taiwan's indoor air quality standards. After adjustment for covariates, the total number of fungal spores and the ozone, Der f 1, and endotoxin levels were significantly associated with increased risks of allergic diseases. Biological contaminants more significantly affected allergic diseases than other pollutants. Moreover, home environmental characteristics (e.g., living near power facilities and gas stations) were associated with an increased risk of allergic diseases. Regular and proper home sanitation is recommended to prevent the accumulation of indoor pollutants, especially biological contaminants. Living away from potential sources of pollution is also crucial for protecting the health of children.

A simple and effective aerosol pathogen disinfection test for a flowing air disinfector

Aerosol transmission is an important disease transmission route and has been especially pertinent to hospital and biosafety laboratories during the SARS-CoV-2 pandemic. The thermal resistance of airborne SARS-CoV-2 is lower than that of Bacillus subtilis spores, which are often used to test the effectiveness of SARS-CoV-2 and other pathogen disinfection methods. Herein, we propose a new method to test the disinfection ability of a flowing air disinfector (a digital electromagnetic induction air heater) using B. subtilis spores. The study provides an alternative air disinfection test method. The new test system combined an aerosol generator and a respiratory filter designed in-house and could effectively recover spores on the filter membrane at the air outlet after passing through the flowing air disinfector. The total number of bacterial spores used in the test was within the range of 5 × 105–5 × 106 colony-forming units (CFUs) specified in the technical standard for disinfection. The calculation was based on the calculation method in Air Disinfection Effect Appraisal Test in Technical Standard for Disinfection (2002 Edition). At an air speed of 3.5 m/s, we used a digital electromagnetic induction air heater to disinfect flowing air containing 4.100 × 106 CFUs of B. subtilis spores and determined that the minimum disinfection temperature was 350 °C for a killing rate of 99.99%. At 400 °C, additional experiments using higher spore concentrations (4.700 × 106 ± 1.871 × 105 CFU) and a higher airspeed (4 m/s) showed that the killing rate remained>99.99%. B. subtilis spores, as a biological indicator for testing the efficiency of dry-heat sterilization, were killed by the high temperatures used in this system. The proposed method used to test the flowing air disinfector is simple, stable, and effective. This study provides a reference for the development of test systems that can assess the disinfection ability of flowing air disinfectors.

The viability of spores is the key factor for microbial induced calcium carbonate precipitation.

While previous studies mainly focused on the total number of spores as an index to predict the calcium precipitation activity (CPA) of bacterial strains, the effect of viability of spores on microbial-induced calcium precipitation (MICP) has remained highly ignored. Therefore, for the first time, we have attempted to optimize the sporulation process in terms of viable spore production and, most importantly, aimed to build a correlation between viable spores and CPA. The results have shown that for the sporulation of Bacillus sp. H4, starch and peptone are the optimal carbon and nitrogen sources, respectively. One gram per liter of sodium chloride promotes CPA and production of viable spores, whereas an increase of sodium chloride concentration beyond 8g L-1 significantly reduces CPA without reducing the quantity of viable spores. Exogenous conditions such as seed age, inoculation quantity, and liquid volume only pose slight influence on the sporulation and CPA. Conclusively, the spores produced under optimized conditions are more morphologically uniform and display a 20% increase in CPA compared to pre-optimized spores. Furthermore, by combining the results of heatmap analysis, it can be concluded that not only the quantity, but also the quality of viable spores is important for bacterial strain to develop high CPA and effective MICP process. This study sheds light on the breadth of biomineralization activity based on viable spores and is an imperative step toward the intelligible design of MICP-based engineering solutions. KEY POINTS: • Viability of spores is a key controlling factor in calcium precipitation activity (CPA). • Spores produced under optimized conditions display a 20% increase in CPA. • Quality of viable spores is imperative for bacterial strains to develop high CPA.

English

The papaya tree is not very exploitable on the international market because of the post-harvest decline of the fruits. In this study, we identified arbuscular mycorrhizal fungi (AMF) from the rhizosphere of papaya in two agroecological zones of Cameroon (Njombe-Pendja: NP and Yaounde: Y). Morphological studies on the density, the rate of root colonization, the diversity of AMF species were evaluated. Molecular identification of AMF was performed by sequencing the small subunit (SSU) 18S rDNA gene region from soil samples. These genes were amplified from the AML and NS2 primers. The total number of spores per 100 g of dry soil was significantly different (P&lt;0.05) depending on the sites, ranging from 391 in NP to 790 in Y sites. The frequency and intensity of root colonization was not significantly different in the two sites. Eleven (11) AMF belonging to seven (7) genera (Scutellospora, Gigaspora, Acaulospora, Entrophospora, Funneliformis, Glomus and Racocetra) were recorded. Two AMF species (T1: Scutellospora rosa and T6: Racocetra gregaria) were recorded at NP and absent at Y. The Shannon-Wiener index revealed a low diversity of AMF species. Homogeneity of species was recorded. Molecular analysis reveals that the AMF species obtained have sizes of 250 bp. Key words: Arbuscular mycorrhizal fungi, Carica papaya L., fungal, molecular and morphological identification, rhizosphere.

Composition and seasonal variation of the arbuscular mycorrhizal fungi spore community in litter, root mat, and soil from a subtropical rain forest

Community composition and seasonal variation of sporulation of arbuscular mycorrhizal fungi (AMF) have been studied in soils from many ecosystems including subtropical forest. Yet, AMF community composition has been surveyed only from the mineral soil but not from the litter layer and the root mat, and long-term variation in sporulation is not fully understood. We sampled a 75-m2 plot from a subtropical forest to determine AMF community composition in the following habitats: the litter layer, the root mat, and the mineral soil. Moreover, samples were taken in fall, winter, spring, and summer over a 2-year period to follow the seasonal variation of AMF sporulation. We detected 47 AMF species belonging to six families and 14 genera, Glomeraceae and Acaulosporaceae being the most represented families. Sixteen species were common to all three habitats, five species were shared between two habitats, and 26 species were recovered exclusively from single habitats. While species richness was not significantly different among habitats, AMF total spore numbers were significantly higher in the litter and root mat compared to the soil. PERMANOVA did not detect a significant effect of habitats on community composition when species presence/absence was considered, but significant differences between litter versus soil and root mat versus soil were detected when spore abundance was considered. A seasonal pattern of spore abundance for species was not observed over the 2-year sampling period regardless of habitat. This study revealed that (i) different AMF species sporulate in the different habitats; thus, field surveys considering only the mineral soil might underestimate species richness and (ii) AMF species sporulate asynchronously in subtropical forest.

Wildfire does not affect spore abundance, species richness, and inoculum potential of arbuscular mycorrhizal fungi (Glomeromycota) in ferruginous Canga ecosystems

Canga ecosystems develop over superficial iron crusts with shallow and nutrient-poor soils. Under these conditions, arbuscular mycorrhizal fungi (AMF) play an important role in helping plants to overcome abiotic and biotic stresses. Canga can suffer periodic burning and yet it is unknown what the impacts of fire are to AMF communities. We aimed to compare AMF in Canga areas affected by burning (BC) with those with no previous history of burning (NC). We compared AMF species composition, spore numbers, species richness, and mycorrhizal inoculum potential. The total number of spores, AMF species richness and mycorrhizal colonization measured in the infectivity bioassay were not significantly different between areas. A total of 23 species in 10 genera were recovered, with most species belonging to Gigasporaceae and Acaulosporaceae. BC and NC shared 52 % of AMF species. Gigaspora albida, Gigaspora gigantea, and Dentiscutata heterogama sporulated exclusively in trap cultures. We concluded that AMF spore communities were not affected by burning in Canga soils as measured by spore abundance, species richness and infectivity. Our data contribute to the inventory of soil biodiversity associated with Canga, a high biodiverse and threatened Brazilian ecosystem.

Validation of a real-time PCR method on pta gene for Clostridium tyrobutyricum quantification in milk

In the dairy industry, the late blowing defect in medium and long ripened cheeses causes important economic losses. This cheese defect, caused mainly by the anaerobic spore former Clostridium tyrobutyricum , is characterized by gas production resulting in holes formation in the paste, and in unpleasant aromas related to the butyrate production. Since longtime, the reference method used to detect the presence of total spore number in milk is the Most Probable Number (MPN), a semi-quantitative method which measures the bacterial growth and the gas production after heat treatment of the samples. This method often gives uncertain results, it requires long incubation periods and fails to differentiate between different species of spore-forming bacteria. A TaqMan real-time quantitative PCR targeting the phosphotransacetylase gene ( pta ) for C. tyrobutyricum was previously developed as an alternative technique to the traditional method, faster and more specific, and therefore of great interest to preventively determine the contamination of milk by C. tyrobutyricum . The aim of this work was the validation of this quantitative real-time PCR protocol for the C. tyrobutyricum detection in milk. Following the method validation, 120 samples of UHT and raw milk artificially contaminated with C. tyrobutyricum spores were analyzed in increasing concentrations, relating the results of the molecular method with those obtained by the MPN. Finally, 144 raw milk samples with a possible natural contamination were analyzed and demonstrated a positivity rate of 15.28% (CI95% 10.31–22.05%). • Validation of a real-time PCR for the C. tyrobutyricum detection in milk. • Method application on both spiked and naturally contaminated samples. • Rapid method to monitor the milk quality to avoid the late blowing defect.

The Annual Variation of Allergenic Cladosporium and Alternaria Spores in the Atmosphere of Büyükorhan (Bursa), Turkey; Effects of Meteorological Factors

Fungal spores are important bio-allergens frequently encountered in the atmosphere. Cladosporium Link and Alternaria Nees spores are generally recorded as dominant in many atmospheric fungal spore studies and have high allergic effects on susceptible individuals. The species belonging to these two genera may live as pathogens on the plants and cause low yield. This study was carried out between January 2012 to December 2013. Durham sampler, which is the device of the gravimetric method, was used in the research. A total of 10817 spores were recorded in the Büyükorhan (Bursa) atmosphere during the consecutive years. 4119 spores belonged to the first year and 6698 to the second year. The total numbers of Cladosporium spores were observed much higher than the total numbers of Alternaria spores in both years. This study aims to determine the variation of atmospheric spores in these two genera during the two years by comparing them with meteorological factors. For both spore types, the maximum spore numbers were found between the June-August term. Summer months revealed a risky period in terms of atmospheric fungal spore allergy for sensitive individuals.

Does a decrease in microbial biomass alter mycorrhizal attributes and soil quality indicators in coal mining areas under revegetation process?

Losses of microbial diversity in degraded ecosystems still have obscure consequences, especially when considering the interaction between arbuscular mycorrhizal fungi (AMF) and soil bacteria. This study investigates the effect of decreasing microbial biomass on mycorrhizal attributes and soil quality indicators. The dilution-to-extinction approach was applied in microcosms to search for associations among bacterial diversity, mycorrhizal attributes, and soil quality indicators. The experiment was conducted with four soil treatments (undiluted control 100 = D0, 10−3 = D3, 10−6 = D6, and 10−9 = D9) from a short-term (two years = 2Y) and a long-term (15 years = 15Y) coal mine revegetation area. Microcosms were inoculated with 300 spores of Acaulospora colombiana, Gigaspora albida, and Claroideoglomus etunicatum with millet as the host plant. Results included the total number of AMF spores, mycorrhizal colonization, soil aggregation, glomalin, fluorescein diacetate hydrolysis (FDA), basal soil respiration, microbial biomass, and soil bacterial microbiome. Larger differences were observed between areas than between dilution treatments within the sampling area. Attributes that presented differences in the dilutions compared to D0 2Y samples were mycorrhizal colonization (D0 = 85% and D9 = 43.3%), FDA (D0 = 77.2% and D9 = 55.5%), extractable glomalin-related soil protein (D0 = 0.09 and D9 = 0.11) and bacterial diversity (D0 = 7.3 and D6 = 5.3). D0 15Y samples presented differences in microbial biomass nitrogen (D0: 232.0) and bacterial diversity (D0: 7.9, D9: 5.6) compared to the dilutions. Bacterial microbiome present in the D0 samples formed distinct clusters as to other samples and correlated with soil aggregation and basal respiration attributes. Results suggest that AMF inoculation and dilution-to-extinction did not affect soil quality indicators preeminently, but the bacterial community is affected and can influence the process of environmental revegetation. A long-term revegetation period is substantial to improve quality indicators and establish the diversity of microorganisms and consequently revegetation in areas impacted by coal mining.

Isolation and identification of indigenous Arbuscular Mycorrhizal Fungi (AMF) of forest clove rhizosphere from Maluku, Indonesia

Abstract. Mahulette AS, Alfian A, Kilkoda KA, Lawalata IJ, Marasabessy DA, Tanasale VL, Makaruku MH. 2021. Isolation and identification of indigenous Arbuscular Mycorrhizal Fungi (AMF) of forest clove rhizosphere from Maluku, Indonesia. Biodiversitas 22: 3613-3619. Forest clove is classified as wild-type and endemic to the Maluku (Moluccas) Islands, Indonesia. The different condition of growing areas causes various types of Arbuscular Mycorrhizal Fungi (AMF) associated with forest clove. The study aimed to identify and obtain indigenous AMF inoculums from the forest clove rhizosphere from two distribution areas in Maluku. The results of AMF identification found two types of spores from the genus Glomus in the rhizosphere of forest cloves from Ambon Island with a spore density of 35/50 g of soil. In comparison, three spores were found in Seram Island, two from the genus Scutellospora and one from the Acaulospora. With an overall spore density of 5/50 g of soil. After culture trapping, there was a change in type and an increase in spore density in soil samples from the rhizosphere of the two forest clove distribution areas. Soil samples from Ambon after trapping culture obtained two new types of spores from the genus Acaulospora with a total spore number of 57/50 g soil while in soil samples from Seram found three new types of spores from the genus Glomus with a total spore count of 104/50 g of soil.

Structure and Composition of Major Arbuscular Mycorrhiza (MA) under Different Farmer Management of Coffee and Pine Agroforestry System

Utilization of Arbuscular Mycorrhiza (MA) as beneficial soil microbes is expected to support nutrient demand for improving crop performance. However, under the agroforestry system that facing a problem on light, water, and nutrients competitions, the role of MA is becoming unclear. The purpose of this research was to examine how far different management in Coffee Pines Agroforestry System (CPAS) affects MA structure and compositions. The relationship between soil parameters (e.g. pH, soil organic C) and MA activities was also being evaluated. The selected plot according to existing management practices were chosen as follows: (1) Low management (LC); (2) High management which then compared to (3) Business As Usual (BAU) plot in which were repeated in triplicate. ANOVA and multivariate analysis were employed to determine the effect of the treatments. The result showed that there were significant differences (p&lt;0.05) in the structure and composition of the MA, in terms of the total number of MA spores and the abundance of Glomus sp. under the coffee tree sampling point, while the lowest number was detected in Gigaspora sp. genera. The more intensive land management resulted in a higher abundance of MA biomass which then leads to increased soil P and uptake-P along with MA infection.

Formação de micorriza em variedades de oliveira (&lt;i&gt;Olea europaea&lt;/i&gt; L.) com potencial de cultivo em Minas Gerais

A oliveira, em razão da elevada demanda por produtos como azeitona e azeite de oliva, apresenta posição de destaque no mercado mundial de alimentos. Para o aprimoramento de seu cultivo, pesquisas relacionadas com fatores de ordem biológica da relação solo-planta estão ganhando enfoque, principalmente quanto ao uso de microrganismos como fungos micorrízicos arbusculares (FMAs). Contudo, há uma grande escassez de informação nessa área no Brasil, tanto em condições controladas quanto realizadas in situ. Nesse sentido, o presente trabalho visou avaliar a formação de propágulos (usando as características micélio extrarradicular, número e diversidade de esporos) de micorrizaem17 variedades de oliveira (Olea europaea L.). Essas variedades, com potencial de cultivo no estado de Minas Gerais, são mantidas no banco de germoplasma da Fazenda Experimental de Maria da Fé – EPAMIG (Empresa Brasileira de Pesquisa Agropecuária de Minas Gerais). Houve resposta distinta entre as variedades de oliveira para a formação de micélio extrarradicular e micorriza, sendo a colonização radicular in situ variada entre 0,4% e 3,6%. Nas condições edafoclimáticas da região de pesquisa não foi detectada nenhuma influência das variedades de oliveira sobre o número total de esporos e a diversidade de FMAs, sendo que as espécies Glomus ambisporum e Acaulospora scrobiculata foram identificadas com maior frequência nas raízes das oliveiras analisadas.

Effect of gamma irradiation on the viability and cellulase production of some filamentous fungi

The motivation of our research is to examine the mutagenic effect of gamma irradiation on cellulase secretion of some filamentous fungi. The spore suspensions of Aspergillus sp. TTG and Trichoderma sp. VTCC were irradiated at dose ranging 0-2500 Gy under gamma Cobalt-60 source at Ha Noi Irradiation Center. The result showed that the survival rate of fungi decreases with the increasing dose. The radiation dose required to kill 90% of the total number of fungal spores (D10) of these strains was about 400 Gy. The viability of Aspergillus sp. TTG and Trichoderma sp. VTCC at 500 Gy were 0.46 % and 0.78%, respectively, while the number of survival spore decreased by 6.5-7.5 Log unit at the dose of 2500 Gy. By screening in PDA medium with the addition of CMC (carboxymethyl cellulose) and Congo red as an indicator of cellulose degradation, hundreds of colonies with higher hydrolysis capacity’s value (HC) compared to the initial strain were observed after irradiation. The colonies expressed the highest cellulose hydrolysis capacity with maximum HC value were obtained at dose range of 700-1500 Gy. It is important to notice the 5 potential mutants including 3 mutants of Aspergillus (TTG-700, TTG-1000 and TTG-1200) and 2 mutants of Trichoderma (VTCC-1000, VTCC-1500) demonstrated the higher CMCase secretion (1.78 – 2.48 times) compared to the wild types. After 5 generations, the enzyme productions of the mutants were fairly stable and there were no differences in growth rates and morphology of each generation. The result of this study is an evidence for using gamma irradiation to improve cellulase production in filamentous fungi.

Arbuscular mycorrhizal fungi and soil aggregation in a no‐tillage system with crop rotation

AbstractCrop rotation adoption in no‐tillage systems (NTS) has been recommended to increase the biological activity and soil aggregation, suppress soil and plant pathogens, and increase the productivity aiming at the sustainability of agricultural areas. In this context, this study aimed to assess the effect of crop rotation on the arbuscular mycorrhizal fungi (AMF) community and soil aggregation in a soil cultivated for nine years under NTS. Treatments consisted of combinations of three summer crop sequences and seven winter crops. Summer crop sequences consisted of corn (Zea mays L.) monoculture, soybean (Glycine max L. Merrill) monoculture, and soybean–corn rotation. Winter crops consisted of corn, sorghum (Sorghum bicolor (L.) Moench), sunflower (Helianthus annuus L.), sunn hemp (Crotalaria juncea L.), pigeon pea (Cajanus cajan (L.) Millsp.), oilseed radish (Raphanus sativus L.), and millet (Pennisetum americanum (L.) Leeke). Soil samples were collected at a depth of 0–0.10 m for analyses of soil chemical, physical, and biological attributes. Spore abundance, total glomalin, and soil aggregate stability index were higher in the soil under corn monoculture. The highest values of aggregate mean weight diameter were observed in the soybean–corn rotation (3.78 mm) and corn monoculture (3.70 mm), both differing from soybean monoculture (3.15 mm), while winter crops showed significant differences only between sorghum (3.96 mm) and pigeon pea (3.25 mm). Two processes were identified in the soil under summer crop sequences. The first process was observed in PC1 (spore abundance, total glomalin, easily extractable glomalin, pH, P, and Mg2+) and was related to AMF; the second process occurred in PC2 (aggregate mean weight diameter, soil aggregate stability index, K+, and organic matter) and was related to soil aggregation. The nine‐year no‐tillage system under the same crop rotation adoption influenced AMF abundance in the soil, especially with corn cultivation in the summer crop sequence, which promoted an increased total external mycelium length and number of spores of AMF. In addition, it favored an increased soil organic matter content, which is directly related to the formation and stability of soil aggregates in these managements.

Spore Density and Arbuscular Mycorrhizal Colonization in Sunflower Grown in Campo Verde (Brazil)

The objective of this study was to evaluate the number of spores and the mycorrhizal root colonization in a Cerrado soil (Red-Yellow Latosol) cultivated with different sunflower genotypes. The sampling of the rhizospheric soil was performed at three growth stages: Sowing, flowering, and harvest. The experimental design was in completely randomized blocks with four replications. Three different sunflower hybrids were tested in the 2009 and 2010 cropping seasons. The collected data comprised the total number of spores per 50 g of soil at the three growth stages, along with arbuscular mycorrhizal fungi (AMF) colonization. It was verified that the mycorrhizal colonization was not influenced by the sunflower genotypes, and the mean spore densities were equivalent to 4.94 and 4.64 g soil-1 in 2009 and 2010, respectively. More importantly, AMF colonization was enhanced by lower soil phosphorus levels. The maximum spore production was obtained at flowering, with mycorrhizal colonization rates ranging from 21 to 28% and from 28 to 48% in 2009 and 2010, respectively. The number of spores also varied from 153 to 342 and from 147 to 320 in 2009 and 2010, respectively.