Fungal Propagules Research Articles

UV-B Radiation Tolerance and Temperature-Dependent Activity Within the Entomopathogenic Fungal Genus Metarhizium in Brazil.

Metarhizium comprises a phylogenetically diverse genus of entomopathogenic fungi. In Brazil, Metarhizium anisopliae s.str. subclade Mani 2 is predominantly isolated from insects, while M. robertsii and M. brunneum mostly occur in the soil environment. Solar radiation and high temperatures are important abiotic factors that can be detrimental to fungal propagules. We hypothesized that among 12 Brazilian isolates of Metarhizium spp., M. anisopliae Mani 2 (n = 6), being adapted to abiotic conditions of the phylloplane, is more tolerant to UV light and high temperatures than M. robertsii (n = 3) and M. brunneum (n = 3). Inoculum of each isolate was exposed to UV-B for up to 8 h and viability evaluated 48 h later. After 8 h under UV-B, most of the isolates had germination rates below 5%. Discs of mycelia were incubated at different temperatures, and diameter of colonies were recorded for 12 days. Mycelia of M. robertsii isolates grew faster at 33 °C, while M. anisopliae and M. brunneum grew most at 25 °C. Dry conidia were incubated at 20, 25 or 40 °C for 12 days, and then viabilities were examined. At 40 °C, conidia of five M. anisopliae isolates were the most tolerant. In the three experiments, considerable intra- and inter-specific variability was detected. The results indicate that conclusions about tolerance to these abiotic factors should be made only at the isolate level.

Fungal diversity present on rocks from a polar desert in continental Antarctica assessed using DNA metabarcoding.

We evaluated the fungal diversity associated with carbonate veins and two types of salt encrustation in rocks in a polar desert region of continental Antarctica using DNA ametabarcoding approach. We detected 262,268 reads grouped into 517 amplicon sequence variants (ASVs) assigned to the phyla Ascomycota, Basidiomycota, Mortierellomycota and Mucoromycota. Fourteen ASVs belonging to the genera Trichosporon, Mortierella, Penicillium, Aspergillus, Cladosporium, Coprinellus, Pleurotus and Pseudogymnoascus were assessed to be dominant taxa. The fungal communities of the three habitats sampled displayed high diversity indices when compared with other habitats of Antarctica, although differing in detail, with the highest diversity indices in the gypsum crust type 2. Only 48 of the 517 ASVs (9.28%) were detected in all three habitats, including dominant, intermediate and minor components. In contrast with previous studies of fungal communities living in the ultra-extreme conditions of continental Antarctica, application of metabarcoding revealed the DNA of a rich and complex resident fungal community. The ASVs detected included fungi with different ecological roles, with xerophilic, human- and animal-associated, phytopathogenic, saprotrophic, mutualistic, psychrotolerant and cosmopolitan taxa. This sequencediversity may be the result of deposition of fungal propagules over time driven by air currents, precipitation or human activities in the region.

Paraphysoderma sedebokerense Infection in Three Economically Valuable Microalgae: Host Preference Correlates with Parasite Fitness.

The blastocladialean fungus Paraphysoderma sedebokerense parasitizes three microalgae species of economic interest: Haematococcus pluvialis, Chromochloris zofingiensis and Scenedesmus dimorphus. For the first time, we characterized the developmental stages of isolated fungal propagules in H. pluvialis co-culture, finding a generation time of 16 h. We established a patho-system to compare the infection in the three different host species for 48 h, with two different setups to quantify parameters of the infection and parameters of the parasite fitness. The prevalence of the parasite in H. pluvialis and C. zofingiensis cultures was 100%, but only 20% in S. dimorphus culture. The infection of S. dimorphus not only reached lower prevalence but was also qualitatively different; the infection developed preferentially on senescent cells and more resting cysts were produced, being consistent with a reservoir host. In addition, we carried out cross infection experiments and the inoculation of a mixed algal culture containing the three microalgae, to determine the susceptibility of the host species and to investigate the preference of P. sedebokerense for these microalgae. The three tested microalgae showed different susceptibility to P. sedebokerense, which correlates with blastoclad’s preference to the host in the following order: H. pluvialis > C. zofingiensis > S. dimorphus.

Hordeum vulgare marketed as food contains potential fungi that synthesize mycotoxin.

The grains of H. Vulgare commonly used for the elaboration of meals for humans and animals, could be contaminated with propagules of native fungi resulted from the intensive agricultural system of production. In addition, the unsuitable storage conditions could strongly influence the growing of undesirable fungi which could potential synthetiz emyco toxins. The aim of the present research work was the isolation of Aspergillus potential to synthetize ochratoxin A from the commercially available in H. vulgare. To this purpose, the grains were collected from various local stores, from grain of H. vulgare. Aspergillus were isolated in potato dextrose and in a Sabourauddextroseagar to determine the density and diversity. The potential for the synthesis of ochratoxin A by Aspergillus strains was then evaluated. The results were statistically evaluated using the software Anova/Turkey. Results indicate the presence of a relatively high number of propagules of Aspergillus spp which are contaminating the H. vulgare. Furthermore, 67% of the fungi present in H. vulgare have the potential to synthetize ochratoxin A. These results demonstrate the risk of consumption of those grains by humans.

Desiccation-tolerant fungal blastospores: From production to application

• Summary of current of drying theory. • Overview over blastospore adaptations to desiccation. • Factors influencing blastospore desiccation tolerance and storage stability • Meta-analysis of current literature onblastospore desiccation research. Increasingly changing climates and ever-growing population sizes paint a worrisome picture of future food scarcity across the globe. Of the potential ways to combat what in many countries is already a problem today, biological pest control is a sustainable approach to ensure crop safety from pest damage. In the biotechnological process from fermentation, to formulation, to desiccation, and finally to storage of the finished biocontrol product, the low desiccation tolerance and shelf life of the biological component is one of the main challenges to overcome. Entomopathogenic fungi, popular and established biocontrol agents, are no exception to this. In many species, a tradeoff between ease of mass production and the shelf life of fungal propagules takes place. Blastospores are easily produced in high quantities, but the desiccation necessary to ensure a sufficient shelf life of blastospore products has a significant impact on blastospore survival. In comparison with other propagule types, blastospores are especially vulnerable to desiccation, so that measures to increase shelf life for successful commercialization must be taken. Fortunately, the multifaceted production process of blastospore biocontrol agents leaves room for vastly different approaches to do so. This review showcases studies from several approaches and puts them into context with the cellular effects of desiccation. The review also evaluates the given literature to facilitate the identification of impactful studies for future blastospore research.

Retrobulbar Cryptococcoma Mimicking Tumor in a Labrador Retriever

Background: Cryptococcosis is a systemic mycotic disease caused by encapsulated yeasts C. neoformans and C. gattii. Cryptococcus neoformans is predominantly found in soils and feces of pigeons and psittacids. Infection occurs mainly through the respiratory tract, through the inspiration of fungal propagules (basidiospores and/or desiccated yeast cells). The main lesions observed are in the nasal cavity and lungs, but in dogs, the central nervous system and eyes are widely affected. Despite some previously mentioned reports, the retrobulbar form has not been described in the literature. Therefore, the purpose of this report is to describe a case of retrobulbar cryptococcoma mimetizing a tumor in a young bitch. Case: A 2-year-old female Labrador Retriever, was admitted to one Veterinary Hospital with exophthalmia on the left eye for 15 days and other signs included negative retropulsion, mydriasis, and abscence of menace and pupillary reflexes. Ocular ultrasound imaging revealed a hyperecotic and heterogeneous retrobulbar mass in the mid-dorsal region compressing the optic nerve. Computed tomography of the skull showed the presence of proliferation of neoplastic tissue in a locally invasive retrobulbar region promoting moderate rostrolateral displacement of the left ocular bulb, discrete osthelysis in maxillary bone, palatine, medial wall of the orbital bone and frontal bone, with destruction of cribiform plate adjacent to the dorsal region of the orbital wall and presence of mild contrast uptake in the region of the left olfactory bulb lobe, characterizing a picture compatible with neoplasia with malignancy and locally invasive characteristics. Exenteration and excision of part of the frontal bone were performed and histopathological examination revealed granulation with the presence of fibroblasts and numerous typical blastoconidia of Cryptococcus neoformans. The patient was treated with Itraconazole [10 mg/kg, v.o, SID, for 90 days] and one year after diagnosis, X-ray was performed to control the lesion and radiographic aspects were within normal limits.Discussion: Cryptococcus sp. is an environmental fungus that has the potential to be pathogenic to humans and animals. Fungus present as a basidiospores in pigeon droppings. The patient described had a history of contact with free-living pigeons, making it a risk factor for the occurrence of cryptococcosis, being the possible cause of the infection. In dogs, the disease is mainly described in immunosuppressed animals, which was not the case of the patient, who presented clinical and laboratory results within the normal range and without a previous history of use of immunosuppressants. The alterations described in the computed tomography, such as destruction of the cribriform plate adjacent to the dorsal region of the left orbital wall and the presence of slight contrast uptake in the left olfactory bulb lobe region, are compatible with the main entry point for propagules of Cryptococcus sp. In the present case, no periocular and ocular alterations were observed as described in the literature, and the lesion was restricted to the retrobulbar space. Ultrasonography and computed tomography revealed a neoformation mimicking a malignant neoplasm and the diagnosis of cryptococcoma was revealed by histopathology. Based on the present case, cytology through aspiration of retrobulbal neoformations is imperative as a diagnostic method, especially in endemic areas for fungal diseases that can mimic ocular neoplasms. Keywords: cryptococcosis, fungus, Cryptococcus sp., dog. Descritores: criptococose, fungo, Cryptococcus sp., cão.

Unintentional transport of fungi propagules to Antarctic biome and the ability to develop at low temperatures

Filamentous fungi relatively easily disperse and colonize a variety of substrates, inhabiting various, often extreme environments. Therefore, they spread all over the world. The purpose of the research was to determine whether the propagules of filamentous fungi brought (accidentally transported) into the Antarctic biome by tourists and members of scientific expeditions are capable of developing at low temperatures. In the studies were used seven isolates of fungi: Penicillium sp., Aspergillus flavus, Alternaria alternata, Cladosporium cladosporioides, Trichoderma viride, Geotrichum candidum and Botrytis cinerea. The isolates came from samples collected from tourists and members of scientific expeditions arriving at the Henryk Arctowski Polish Antarctic Station on King George Island in the South Shetland archipelago. Fungal growth was measured at 0, 5, 10, 22°C (as a control) and 10° C, but after having frozen inoculum at -15°C for a period of 7 days. Penicillium sp., Alternaria alternata, Cladosporium cladosporioides, Trichoderma viride, Geotrichum candidum and Botrytis cinerea were found to be capable of growing at low temperatures (5 and 10oC as well as after one freezing cycle, down to -15oC and thawing, up to +10oC). They did not produce a macroscopically visible mycelium at temp. 0oC, however, it was not a lethal temperature for them, as when they were transferred to higher temperatures, they continued to develop even after a fairly long time following the beginning of the experiment. The most vulnerable was Aspergillus flavus. At lower temperatures (from about to 5oC) it did not develop, while freezing and thawing were lethal for this species. Some species (G. candidum, T. viride and B. cinerea), despite the development of mycelium, did not produce spores at lower temperatures.

Diversity and seasonal dynamics of culturable airborne fungi in a cultural heritage conservation facility

An extensive aeromycological survey was performed in the premises of a cultural heritage conservation facility to estimate fungal propagule concentrations in both indoor and outdoor air and seasonal dynamics with regard to temperature and air humidity. The highest average propagule concentration in indoor air was documented in spring, and for outdoor air, in summer. Increased propagule loads were documented in most rooms during winter, fall and spring, and in all examined rooms in summer. Very high propagule concentrations (>25,000 CFU m−3) were reported in ground-floor rooms. The total mycobiota was comprised of 74 fungal species, with a prevalence of Aspergilli and Penicillia. Cladosporium and Penicillium isolates were found to be the most abundant in all seasons in both indoor and outdoor air samples. Among the identified fungi, potential human pathogens, allergens and mycotoxin producers were present. Numerous documented species play an important role in the deterioration of cultural heritage artifacts and are known producers of extracellular enzymes, acids and pigments. Application of a selective medium (M40Y) allowed isolation of various xerophiles and xerotolerant species. Aeromycological analyses are mandatory for determining the appropriate conditions for the protection of the health of conservators, as well as the objects of cultural heritage.

UV-B tolerances of conidia, blastospores, and microsclerotia of Metarhizium spp. entomopathogenic fungi.

The aim of the present study was to analyze ten native Metarhizium spp. isolates as to their UV-B tolerances. Comparisons included: different fungal propagules (conidia, blastospores, or microsclerotia [MS]); conidia in aqueous suspensions or in 10% mineral oil-in-water emulsions; and conidia mixed with different types of soil. The UV-B effect was expressed as the germination of conidia or culturability of blastospores and MS relative to nongerminated propagules. Metarhizium anisopliae LCM S05 exhibited high tolerance as blastospores and/or MS, but not as conidia; LCM S10 and LCM S08 had positive results with MS or conidia but not blastospores. The formulations with 10% mineral oil did not always protect Metarhizium conidia against UV-B. Conidia of LCM S07, LCM S08, and LCM S10 exhibited the best results when in aqueous suspensions, 24 h after UV-B exposure. In general, conidia mixed with soil and exposed to UV-B yielded similar number of colony forming units as conidia from unexposed soil, regardless the soil type. It was not possible to predict which type of propagule would be the most UV-B tolerant for each fungal isolate; in conclusion, many formulations and propagule types should be investigated early in the development of new fungal biocontrol products.

Characterization of ice nucleating particles in rainwater, cloud water, and aerosol samples at two different tropical latitudes

Ice nucleating particles (INPs) induce ice crystal formation and therefore, they are able to influence precipitation development. INP sources remain highly uncertain, with most of the observational studies performed in mid- and high-latitudes, bypassing the Tropics. In the present study, rainwater, cloud water, and aerosol samples were collected during the rainy seasons in 2018 and 2019 in two major tropical capital cities: Quito and Mexico City, and at the high-altitude rural site Altzomoni (Mexico). The ice nucleating abilities of the rainwater samples from the urban sites (INP concentrations varying between 1.1 × 102 and 105 L−1 water at −9 °C and −24 °C) were not influenced by the pollution levels, consistent with the literature for other cities (e.g., Beijing and New Delhi), suggesting similarities in the behavior of INPs in densely populated and polluted cities. On the other hand, although the INP concentrations of the rural site samples were similar to those found in Quito and Mexico City (i.e., 7.1 × 101 and 1.1 × 105), their onset freezing temperatures (T0) were found to be higher (−7.5 °C as the highest). In terms of T50 (the temperature at which 50% of the droplets freeze), the rainwater and the cloud water samples were found to be more efficient than the aerosol samples. The ice nucleating abilities of the rural site samples were reduced when applying the heating test, resulting in lower T0 values, by more than 5 °C. Moreover, the presence of bacteria and fungal propagules on the rainwater and cloud water samples was also confirmed. Therefore, the high ice nucleating abilities observed on the samples from the rural site are likely related to biological material. Although K, Ca, S, Zn, and NO3− were found to be enriched in the cloud water samples in comparison to the aerosol particles, only Cu, Mn, and Zn were found to moderately correlate with the INP concentrations at −15 °C and −17 °C out of all the elements detected. Finally, the rainwater samples collected at those tropical sites were found to contain INPs concentrations lower than those found in other mid- and high-latitude sites. The information herein will improve the knowledge of INPs' contained in precipitation, their influence in tropical latitudes, and the development of new parameterizations.

A preliminary investigation on airborne fungi of pedestrian underpasses

Pedestrian underpasses are the unique environment where air transaction with outdoor is complicated, inducing interest to study the air quality for the presence of microbes. Thus, the study on the presence of airborne fungi from 11 different underpasses in Chennai city was conducted. The airborne fungi was monitored by exposing potato dextrose agar strips in reuter centrifugal sampler (RCS). A total of 1735 colonies were isolated from underpasses and the control site recorded only 1255 colonies. Total average colony forming unit of underpasses and control site was 157.7 CFU/m3 of air and 114.09 CFU/m3 of air, respectively. Altogether 22 species classified in 16 genera were isolated from both the environments. Of which 21 species belonging to 16 genera were isolated from underpasses whereas the control site yielded 15 species belonging to 12 genera. The isolated species were categorized into three species belonging to Zygomycota, 2 species to Ascomycota and the remaining to Mitosporic fungi. The air sample in the underpass is dominated by the presence of the fungi, Aspergillus flavus, Curvularia lunata and A.niger, whereas the control is dominated by Cladosporium cladosporioides, Aspergillus niger and A. flavus. The study proves the underpasses are a favorite niche for the proliferation of fungal propagules and proper maintenance of underpass is recommended.

DNA Metabarcoding to Assess the Diversity of Airborne Fungi Present over Keller Peninsula, King George Island, Antarctica.

We assessed fungal diversity present in air samples obtained from King George Island, Antarctica, using DNA metabarcoding through high-throughput sequencing. We detected 186 fungal amplicon sequence variants (ASVs) dominated by the phyla Ascomycota, Basidiomycota, Mortierellomycota, Mucoromycota, and Chytridiomycota. Fungi sp. 1, Agaricomycetes sp. 1, Mortierella parvispora, Mortierella sp. 2, Penicillium sp., Pseudogymnoascus roseus, Microdochium lycopodinum, Mortierella gamsii, Arrhenia sp., Cladosporium sp., Mortierella fimbricystis, Moniliella pollinis, Omphalina sp., Mortierella antarctica, and Pseudogymnoascus appendiculatus were the most dominant ASVs. In addition, several ASVs could only be identified at higher taxonomic levels and may represent previously unknown fungi and/or new records for Antarctica. The fungidetected in the air displayed high indices of diversity, richness, and dominance. The airborne fungal diversity included saprophytic, mutualistic, and plant and animal opportunistic pathogenic taxa. The diversity of taxa detected reinforces the hypothesis that the Antarctic airspora includes fungal propagules of both intra- and inter-continental origin. If regional Antarctic environmental conditions ameliorate further in concert with climate warming, these fungi might be able to reactivate and colonize different Antarctic ecosystems, with as yet unknown consequences for ecosystem function in Antarctica. Further aeromycological studies are necessary to understand how and from where these fungi arrive and move within Antarctica and if environmental changes will encourage the development of non-native fungal species in Antarctica.

Distribution of airborne pollen, fungi and bacteria at four altitudes using high-throughput DNA sequencing

The diversity and composition of bioaerosols in the atmosphere have been studied in the recent years in multiple places and under very different meteorological conditions. Pollen grains, fungal propagules and bacteria are the most studied airborne biological particles, usually individually, and correlated to environmental factors such as temperature, wind speed, rain, air pollution, etc. to understand their influence. However, the effect of the height on the distribution and composition of these bioaerosols has not been properly described so far. In this research, we analyzed concurrently these three biological particles at four different heights (1.5 m, 130 m, 500 m and 1000 m) by high-throughput DNA sequencing. We observed that the atmosphere contains a homogeneous distribution and composition of biological particles regardless of the altitude tested. Only a minority of the taxa is differently distributed. Therefore, we here deduce that the altitude does not drastically influence the airborne bioparticles distribution and composition under similar meteorological conditions. We also studied the co-occurrence between different bioaerosols, finding new potential relationships.

PROPÁGULOS FÚNGICOS Y PARTÍCULAS CONTAMINANTES PRESENTES EN FOSAS NASALES DE VOLUNTARIOS EN LA UNIVERSIDAD AUTÓNOMA METROPOLITANA UNIDAD XOCHIMILCO

The emission of pollutants into the atmosphere of Mexico City and the metropolitan area causes air quality problems. Part of the inorganic compounds comes from natural and anthropogenic processes. However, bioaerosols such as fungi are also present, and they are capable of causing respiratory diseases. The objective of the investigation was a preliminary study for the recovery and identification of fungal propagules from samples of members of the Universidad Autonoma Metropolitana-Xochimilco community. Thirteen volunteers underwent nasal washes upon arrival at the university and after an hour, Petri dishes were placed for sedimentation by gravity in the places where they were between samplings. Part of the sample was placed in Bengal rose agar, another fraction was observed under a microscope and another was used for the analysis of elemental chemistry. As results, the most frequent fungal genera were Penicillium and Cladosporium, and Penicillium by sedimentation. Yeasts were also isolated; the species with the highest number of colonies from nasal washes were Candida guilliermondii and C. tropicalis, by sedimentation Cryptococcus humicola. Among the elements identified were traces of metals such as Ti, Zn, Cr, Fe, and Ni. Nasal washes can be used as a strategy to know the fungal microbiota in the respiratory tract, as well as part of preventive strategies in the diagnosis of respiratory diseases.

Trait-based aerial dispersal of arbuscular mycorrhizal fungi.

Dispersal is a key process driving local-scale community assembly and global-scale biogeography of plant symbiotic arbuscular mycorrhizal (AM) fungal communities. A trait-based approach could improve predictions regarding how AM fungal aerial dispersal varies by species. We conducted month-long collections of aerial AM fungi for 12 consecutive months in an urban mesic environment at heights of 20 m. We measured morphological functional traits of collected spores and assessed aerial AM fungal community structure both morphologically and with high-throughput sequencing. Large numbers of AM fungal spores were present in the air over the course of one year and these spores exhibited traits that facilitate aerial dispersal. Measured aerial spores were smaller than average for Glomeromycotinan fungi. Trait-based predictions indicate that nearly 1/3 of described species from diverse genera demonstrate the potential for aerial dispersal. Diversity of aerial AM fungi was relatively high (20 spore species and 17 virtual taxa) and both spore abundance and community structure shifted temporally. The prevalence of aerial dispersal in AM fungi is perhaps greater than previously indicated and a hypothesized model of AM fungal aerial dispersal mechanisms is presented. Anthropogenic soil impacts may liberate AM fungal propagules initiating the dispersal of ruderal species.

Development of an attract-and-infect device for biological control of lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae) in poultry houses

The lesser mealworm, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), is the most important pest in poultry production systems worldwide. Adults and larvae serve as alternative low-quality food for chickens and as a vehicle for animal pathogens resulting in significant economic losses for farmers. Control of this pest is usually performed through insecticide application during the interval between chicken flocks. However, due to the cryptic behaviour of this pest, chemical control is usually not effective. With the aim of developing a sustainable approach to control A. diaperinus, we evaluated integration of the A. diaperinus aggregation pheromone with a highly virulent strain (Unioeste 04) of the fungus Beauveria bassiana (Bals.) Vuill. (Ascomycota: Cordycipitaceae) using an attract-and-infect device. Significant levels of A. diaperinus mortality and lower numbers of offspring (larvae) were observed in laboratory experiments using Unioeste 04. Horizontal transmission of the Unioeste 04 strain through contaminated living A. diaperinus and cadavers was also observed. In field experiments in commercial poultry houses, a significant level of A. diaperinus mortality was observed in Unioeste 04-treated arenas. The results show that the A. diaperinus aggregation pheromone can be used as an attractant in a device impregnated with infective fungal propagules, increasing adult infection and enhancing disease spread. In addition, the use of the microbial control agent inside the device allows the fungus to remain effective for longer periods in the adverse conditions of the poultry house environment.

Characterisation of fungal and bacterial dynamics in an active green wall used for indoor air pollutant removal

Indoor air quality (IAQ) is of growing public health concern which has prompted the use of plants to phytoremediate air pollution in interior spaces. Active green walls are emerging as a means of reducing indoor contaminants and have demonstrated efficacy comparable to conventional air filtering technologies. However, the use of active airflow through organic substrates has the potential to emit bioaerosols into the surrounding environment, where the potential risk to human health is largely unknown. In this study, we demonstrate that two indoor green walls (with and without active airflow) contribute significantly to the ambient fungal load, however concentrations remained well below WHO safety guidelines. Bacterial dynamics within the rhizosphere/substrate of the operational botanical biofilters displayed variability across plant species. Phyla-wide distribution generally aligned with previous literature; however, differences from those previously reported were observed at the genus level, possibly due to geographic location, substrate composition, or plant species selection. Targeted assessment of Legionella aerosol contamination, an under-addressed potential pathogen for these active systems, yielded no positive identification during the sampling period. We conclude that active green walls host a unique bacterial profile and do not emit harmful levels of fungal propagules or pose significant risk of aerosolised Legionella species, provided systems are well monitored and maintained.

Differential susceptibility of blastospores and aerial conidia of entomopathogenic fungi to heat and UV-B stresses

We investigated the comparative susceptibility to heat and UV-B radiation of blastospores and aerial conidia of Metarhizium spp. (Metarhizium robertsii IP 146, Metarhizium anisopliae s.l. IP 363 and Metarhizium acridum ARSEF 324) and Beauveria bassiana s.l. (IP 361 and CG 307). Conidia and blastospores were produced in solid or liquid Adámek-modified medium, respectively, and then exposed to heat (45 ± 0.2 °C) in a range of 0 (control) to 360 min; the susceptibility of fungal propagules to heat exposures was assessed to express relative viability. Similarly, both propagules of each isolate were also exposed to a range of 0 (control) to 8.1 kJ m−2 under artificial UV-B radiation. Our results showed that fungal isolates, propagule types and exposure time or dose of the stressor source play critical roles in fungal survival challenged with UV-B and heat. Conidia of ARSEF 324, IP 363, IP 146 and IP 361 exposed to heat survived significantly longer than their blastospores, except for blastospores of CG 307. Conidia and blastospores of IP 146 and IP 363 were equally tolerant to UV-B radiation. We claim that blastospores of certain isolates may be promising candidates to control arthropod pests in regions where heat and UV-B are limiting environmental factors.

A novel chitosan biopolymer based Trichoderma delivery system: Storage stability, persistence and bio efficacy against seed and soil borne diseases of oilseed crops

Management of seed and soil borne fungal plant pathogens using fungal species belonging to the genus Trichoderma is gaining importance. Seed coating with powder based formulations of Trichoderma is most widely adopted by the researchers and farmers as well. Delivery system that leads to good adherence of fungal propagules on seed surface, minimizing the wastage of active ingredient, sustained and timely release during treatment process is very important for effective season long protection. Chitosan-PEG (Polyethylene glycol) (Cts-PEG) blend containing Trichoderma harzianum (Th4d) (Cts-PEG-Th) spores is developed and its storage stability, persistence in soil and bio efficacy against seed and soil borne pathogens of groundnut and safflower crops is studied. The blend was stable without much changes in pH throughout the storage period. Persistence studies conducted for 3 months revealed that Cts-PEG-Th amended soil, Trichoderma got released from polymer film slowly and reached a maximum of log 8 CFUs by 30 days and there after started declining to retain log 6 CFUs at 90 days. In shelf life study, the chitosan blend was able to maintain Trichoderma counts of log 10.0 and log 10.2 over a period of 6 months at storage temperatures of 30 °C and 4 °C, respectively and the antagonistic activity unaffected against three plant pathogens viz. Macrophomina phaseolina, Fusarium oxysporumf. sp.ricini and Aspergillus niger over a period of 6 months of storage. Bio efficacy testing in germination towels and green house pot studies revealed the effectiveness of seed treatment with Cts-PEG-Th blend significantly increasing the germination and seedling vigour and reducing the diseases in groundnut (peanut) and safflower.

The Differential Vertical Distribution of the Airborne Biological Particles Reveals an Atmospheric Reservoir of Microbial Pathogens and Aeroallergens.

The most abundant biological particles present in the air are bacteria, fungal propagules and pollen grains. Many of them are proved allergens or even responsible for airborne infectious diseases, which supports the increase of studies in recent years on their composition, diversity, and factors involved in their variability. However, most studies in urban areas are conducted close to ground level and a factor such as height is rarely taken into account. Thus, the information about how the composition of biological particles changeswith this variable is scarce. Here, we examined the differential distribution of bacteria, fungi, and plants at four altitudes (up to ∼ 250m) in a metropolitan area using high-throughput DNA sequencing. Most taxa were present at all levels (common taxa). However, a transitional layer between 80 and 150m seemed to affect the scattering of these bioaerosols. Taxa not present at all altitudes (non-common) showed an upward tendency of diversity for bacteria and plants with height, while the opposite trend was observed for fungi. Certain patterns were observed for fungi and specific plant genera, while bacterial taxa showed a more arbitrary distribution and no patterns were found. We detected a wide variety of aeroallergens and potential pathogens at all heights, which summed a substantial portion of the total abundance for fungi and plants. We also identified potential connections between the biological particles based on their abundances across the vertical section.