Number Of Fungal Colony-forming Units Research Articles

Accessing the Life in Smoke: A New Application of Unmanned Aircraft Systems (UAS) to Sample Wildland Fire Bioaerosol Emissions and Their Environment

Wildland fire is a major producer of aerosols from combustion of vegetation and soils, but little is known about the abundance and composition of smoke’s biological content. Bioaerosols, or aerosols derived from biological sources, may be a significant component of the aerosol load vectored in wildland fire smoke. If bioaerosols are injected into the upper troposphere via high-intensity wildland fires and transported across continents, there may be consequences for the ecosystems they reach. Such transport would also alter the concept of a wildfire’s perimeter and the disturbance domain of its impact. Recent research has revealed that viable microorganisms are directly aerosolized during biomass combustion, but sampling systems and methodology for quantifying this phenomenon are poorly developed. Using a series of prescribed fires in frequently burned forest ecosystems, we report the results of employing a small rotary-wing unmanned aircraft system (UAS) to concurrently sample aerosolized bacteria and fungi, particulate matter, and micrometeorology in smoke plumes versus background conditions. Airborne impaction-based bioaerosol sampling indicated that microbial composition differed between background air and smoke, with seven unique organisms in smoke vs. three in background air. The air temperature was negatively correlated with the number of fungal colony-forming units detected. Our results demonstrate the utility of a UAS-based sampling platform for active sampling of viable aerosolized microbes in smoke arising from wildland fires. This methodology can be extended to sample viable microbes in a wide variety of emissions sampling pursuits, especially those in hazardous and inaccessible environments.

Fungi in bottom sediments of the barents and Kara seas

The mycobiota of bottom sediments at depths of 128−472 m was investigated in Barents and Kara sea areas remote from the shore. The species composition and fungal abundance, that is, the number of fungal colony-forming units (CFUs), were determined in 5 samples from the Kara Sea and in 14 samples of the Barents Sea. For the first time for the Arctic seas, the fungal biomass was determined in 12 samples of the bottom sediments from the Barents Sea. It was found that fungal abundance in the bottom sediments of the both seas did not exceed 13 CFUs per 1 g of dry substrate weight. In total, only 58 colonies of filamentous fungi belonging to 22 morphotypes, 8 of which were sterile, were isolated from all the samples. No more than six morphotypes were contained in 1 g of dried substrate; they were mostly species of the genus Cladosporium and sterile isolates. The study of the fungal biomass detected both spores and fungal mycelium in the bottom sediments. The total biomass was extremely low and ranged from 0.1 to 0.620 mg/g of the studied substrate. Small spores (with a diameter less than 3 μm) absolutely predominated (from 88 to 99.7% of the biomass).

Changes in fungal communities in organically fertilized soil

The research project was carried out as a field experiment with application of the following crop rotation system: industrial potato, spring barley for fodder, winter rape and winter wheat, established in the random distribution of blocks in triplicate on gleyic luvisol formed of silty light loam. The aim of the research was to determine the influence of diversified organic fertilization based on composted wastewater sediments and farm manure on the community of soil fungi as compared to fields without fertilization and with NPK fertilization only. The fungi were cultured on the Martin medium and were counted and identified afterwards. As a result of three-year field experiments it was established that organic fertilization had a more determining effect on qualitative composition than numbers of soil fungi. Total number of fungal colony-forming units in the soil fertilized with Biohum at 10 t/ha and 5 t/ha was significantly higher than in soil with mineral NPK fertilization and without fertilization. Most frequently pathogens populated the soil in fields without fertilization and to a lesser extent the soil with mineral NPK fertilization. A positive influence of organic fertilizers on the fungal community structure was recorded. The number of pathogens was limited (to 1.2% in fields fertilized with farm manure) while the population of saprotrophic fungi possessing antagonistic properties increased.

Interaction Between the Subterranean Termite <I>Reticulitermes flavipes</I> (Isoptera: Rhinotermitidae) and the Entomopathogenic Fungus <I>Metarhizium anisopliae</I> in Foraging Arenas

The entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorokin was tested in the laboratory against field-collected groups of eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), in foraging arenas to determine the potential effect of a "trap and treat" protocol (trapping a part of the population, treating it with a biological control agent and releasing it back into the original population). Individual termites were treated with a suspension of M. anisopliae conidia and released back into the arenas containing untreated termites. After 5 d, 90% of the treated termites died in the arena, but untreated termites did not exhibit a significant increase in mortality within 90 d after release, indicating no transfer of viable M. anisopliae and no epizootic. Although M. anisopliae was isolated from the arenas after 90 d, the average number of fungal colony-forming units recovered was <0.1% of the conidia introduced.

Airborne fungal colony-forming units in outdoor and indoor environments in Yokohama, Japan.

The fungal concentration and flora in indoor and outdoor air in Yokohama, Japan were analyzed with a Reuter centrifugal air sampler and dichloran 18% glycerol agar (DG18), and compared with the levels assessed with potato dextrose agar (PDA). The number of fungal colony-forming units (CFU) in outdoor air was < 13-2750/m3; Cladosporium spp. predominated, followed by Alternaria spp. and Penicillium spp. The fungal concentration in outdoor air peaked in September. The concentrations of fungi in outdoor air (n = 288) were significantly correlated with the maximum temperature of the day, minimum temperature of the day, average temperature of the day, average velocity of wind of the day, average temperature of the month, average relative humidity of the month and precipitation of the month. In indoor air, the fungal CFU was < 13-3750/m3. Cladosporium spp. predominated, followed by the xerophilic fungi such as the Aspergillus restrictus group, Wallemia sebi, the A. glaucus group, and Penicillium spp. The fungal concentration in indoor air peaked in October. The concentrations of fungi in indoor air (n = 288) were significantly correlated with the indoor temperature, indoor relative humidity and the outdoor climatic factors mentioned above, except for the average velocity of wind of the day.

Quantitative changes in fungal colony-forming units in the surface microlayers of two freshwater ponds

The surface microlayer of two small ponds in Wisconsin were studied from March 1979 through November 1979 using glass plate and screen microlayer sampling devices. The numbers of fungal colony-forming units (CFU) in the surface microlayer were determined and compared with numbers in subsurface waters; diel fluctuations were correlated with nutrients; and experiments were conducted to estimate the contribution of spores to surface microlayer populations. The data obtained indicates that the highest number of fungal CFU were located in the surface microlayers of the ponds studied. The numbers present, as well as their enrichment in the surface microlayer, underwent both seasonal and diel fluctuations. Most of the fungal CFU in the surface microlayer appeared to be spores arriving from both allochthonous and autochthonous sources. Qualitative investigations would be necessary to determine the relative importance of either source to the total numbers of fungi observed.