Effect of fire on soil microorganisms in a meghalaya pine forest

The effect of man-made fire on soil mierobial population in a natural subtropical pine forest eco-system, was studied. A nearly fifty years old pine(Pinus kesiya Royle) forest was cut and burnt in March 1977. Another half of this pine forest was left uncut and unburnt. Microbial population was destroyed completely just after the burning and recolonization occurred after some days. Bacteria and actinomycetes were found to be the first colonizers followed by fungi. Burning initiated better growth and higher population of bacteria after two or three showers. Bacterial population was highest in July in burnt and in May in unburnt forest. Maximum fungal population in burnt site was recorded in July while it was highest in April and May in unburnt site.Penicillium spp.,Cladosporium sp. andTrichoderma sp. were found to be first colonizing fungi just after the burning. In unburnt forest eco-systemAbsidia sp.,Trichoderma sp.,Fusarium sp. andPenicillium spp. were found to be dominant.     

Airborne fungi associated with ornamental plant propagation in greenhouses

The objective was to determine potential exposure to airborne fungi in greenhouses and to characterize the temporal patterns of airborne fungi in relation to environmental conditions. We analyzed air samples collected in two greenhouses. Results showed that the top 5 fungi in greenhouse 1 were Trichoderma, hyphal fragments, Aspergillus/Penicillium-like, Cladosporium, and Botrytis in a descending order. Those in greenhouse 2 were Aspergillus/Penicillium-like, Cladosporium, Botrytis, yeast-like, and hyphal fragments. Maximum concentrations of Trichoderma and total spores in greenhouse 1 were 36,426 and 49,729 spores/m³, respectively. Maximum concentrations of Aspergillus/Penicillium and total spores in greenhouse 2 were 46,961 and 71,037 spores/m³, respectively. Airborne fungal populations fluctuated dramatically within 2 h during work hours, tenfold for Aspergillus/Penicillium, 66-fold for Trichoderma, and sevenfold for total spores. QPCR detected Trichoderma harzianum ranging from 7 to 3,500 conidia E/m³. Aspergillus/Penicillium and Botrytis showed diurnal patterns, but not Trichoderma. Aspergillus/Penicillium and Cladosporium were positively correlated with temperature, relative humidity, dew point, heat index, and light and negatively with air movement and air pressure. Botrytis and Trichoderma were not correlated with the environmental factors. Greenhouse workers were potentially exposed up to 71,037 spores/m³ of airborne fungi.     

Keratinophilic fungi in the antarctic environment

Results of a study on the diffusion of keratinophilic fungi in an Antarctic environment are given. Nine soil samples collected from as many sites along the coast of Ross Sea, and six dust samples inside the Italian scientific base were examined by direct inoculation and hair baiting methods for soil samples and plate dilution method for dust samples. As regards the variety of species isolated and the counting of the numbers of colonies, plate dilution method proved to be very effective.Aspergillus spp.,Cladosporium sp., Dematiaceae,Fusarium sp.,Geomyces pannorum v.pannorum, G. pannorum v.vinaceus, Mycelia sterilia,Penicillium spp. were isolated from soil. From the dust the following moulds were isolated:Aphanoascus fulvescens, Aspergillus sp.,Beauveria sp.,Chrysosporium carmichaelii, Dematiaceae, Geomyces pannorum v.pannorum, G. pannorum v.vinaceus, Malbranchea gypsea, Mycelia sterilia, Nectria inventa, Penicillium spp.,Scopulariopsis brevicaulis, Scopulariopsis sp. andTrichophyton mentagrophytes. The presence of four colonies ofTrichophyton mentagrophytes is emphasized and correlated with the anthropization process.     

Initial observations on the cellulolytic activities of some fungal isolates

Summary The cellulolytic activities of aTrichoderma sp.,Penicillium sp.,Cladosporium sp.,Trichoderma viride ATCC-24687,Myrothecium roredium, ATCC-28814 and unidentified fungus (F-4) were investigated. TheTrichoderma sp. and the unidentified fungus (F-4) secreted larger amounts of cellulase into the growth medium than the other strains. They also saccharified lignocellulosics more rapidly than the other strains.

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Resumen Se estudió la actividad celulolítica de: une especie deTrichoderma sp.,Penicillium sp.,Cladosporium sp.,Trichoderma viride ATCC-24687,Myrothecium roredium, ATCC-28814, y de un hongo no identificado (F-4).Trichoderma sp. y el hongo no identificado secretaron más cantidad de celulasa al medio de cultivo que las otras cepas estudiadas. Tambien saccarificaron materiales lignocelulósicos más rápidamente que los demás hongos.

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Résumé Les activités cellulolytiques d'unTrichoderma sp., d'unPenicillium sp., d'unCladosporium sp., d'unTrichoderma viride ATCC-24687, d'unMyrothecium roredium et d'une moisissure nonidentifiée (F-4) ont été examinées. La soucheTrichoderma sp et la moisissure non-identifiée (F-4) ont secrété des quantités plus importantes de cellulase dans le milieu du culture que les autres souches. Ces deux souches ont aussi saccharifié la ligno-cellulose plus rapidement que les autres souches.

     

Mycotoxin-producing potential of fungi isolated from red kidney beans

The predominant fungi present in samples of reject and retail red kidney beans were Aspergillus glaucus, Penicillium spp. and Alternaria spp. Together with A. ochraceus, A. flavus, Fusarium spp., and Trichoderma, these isolates from the reject beans were screened for numerous mycotoxins by TLC. The most consistently produced mycotoxins were penicillic acid (from A. ochraceus and Penicillium spp.) and Alternaria toxins (tenuazonic acid and alternariol). A. glaucus strains were tested for cytotoxicity in three tissue culture cell lines with positive results.     

Degradation of Alachlor [2-chloro-N-(methoxymethyl)-2′,6′-diethylacetanilide] by soil fungi

Summary A Penicillium sp. and a Trichoderma sp. were isolated from a soil previously treated with alachlor which is commonly used as herbicide. These fungi were found to degrade alachlor and only one degradation product was observed after 15 days of incubation. Whereas two products were noticed after 30 days with both the test organisms. re]19740913     

Indoor airborne fungi as risk factors in IgE-mediated respiratory allergy

The purpose of this epidemiological study was to assess respiratory allergy in relation to the presence of indoor airborne fungi. The relationship between IgE-mediated respiratory allergy (skin test positivity) and the presence of fungi (CFU/m³) in the indoor environments of 104 subjects was assessed in a cross-sectional study by controlling for extraneous variables (age, gender, predisposition, asthma, rhinitis, skin positivity to ragweed and mite, and smoking). The qualitative and quantitative measurements of airborne seasonal fungi (Alternaria spp. andCladosporium spp.) and non-seasonal airborne fungi (Penicillium spp. andAspergillus spp.) were taken in the subjects’ indoor environments twice in a 2-year period by volumetric methods (Burkard Personal Sampler). There was a significant association between skin test positivity to seasonal fungi and to ragweed (Adj. OR=3.42, CI=1.76–6.66). There was no association between skin test positivity to seasonal fungi and asthma (Adj. OR=0.52, CI=0.28–0.98), but a significant association was found between skin test positivity to seasonal fungi and rhinitis (Adj. OR=5, CI=2.03–12.32). In a logistic regression analysis (maximum likelihood estimates—model A), no statistical association was found indoors between skin prick test positivity to seasonal fungi (Alternaria and/orCladosporium) and airborneAlternaria and/orCladosporium concentrations (Adj. OR=1.18, CI=0.66–2.07). There was a significant association between skin prick test positivity to seasonal fungi and to non-seasonal fungi (Adj. OR=12.81, CI=1.67–98.34). There was no association between asthma and airbornePenicillium concentrations (Adj. OR=1.86, CI=0.47–7.33) nor between rhinitis and airbornePenicillium concentrations (Adj. OR=0.18, CI=0.03–1.19). In another logistic regression analysis (maximum likelihood estimates — model B) using non-seasonal fungi (Aspergillus andPenicillium), no statistical association was found indoors between skin prick test positivity to non-seasonal fungi and airbornePenicillium concentrations (Adj. OR=0.33, CI=0.07–1.69). These findings suggest an association between rhinitis and seasonal fungi. In the rhinitis stratum, subjects who had skin test positivity to ragweed had a higher risk of being sensitive to seasonal airborne fungal allergens. Subjects with non-seasonal fungal allergy had a high relative risk if they were also allergic to seasonal fungi. There was no association between asthma and airborne fungi, as the epidemiological study (cross-sectional design), by definition, does not allow an etiological evaluation of chronic disease. This would require a longitudinal study, i.e. the measurement of repeated exposure as an independent variable (allergen) and repeated measurement as a function of the disease as outcome in humans as a dependent variable.     

Effects of nematodes,fungi and bacteria on the growth of young apple trees grown in apple replant disease soil

Growth, dry root weight of seedlings and root score of apple seedlings cv. McIntosh were reduced when soils were inoculated with Pratylenchus penetrans, Penicillium janthinellum, Constantinella terrestris, Trichoderma sp., and 4 strains of Bacillus subtilis. Trichoderma sp., and B-1 and B-26 strains of B. subtilis alone reduced plant growth but the combination of Trichoderma sp. + B. subtilis (B-1) and Trichoderma sp. + B. subtilis (B-26) increased plant height. Plant height, root weight and root score were significantly reduced when P. penetrans plus B. subtilis or P. penetrans plus fungi plus bacteria were present in the soil. It is suggested that fungi, bacteria, nematodes alone or their combinations such as nematodes plus bacteria or nematodes plus fungi plus bacteria may contribute towards the occurrence of apple replant disease.Contribution number 700.Contribution number 700.     

Keratinophilic fungi isolated from antarctic soil

In the present study, 10 soil samples were collected aseptically from an equal number of areas of the Antarctic in the zone occupied by the 1986–1987 Italian expedition for research on keratinophilic fungi.Of particular interest was the isolation of a pathogenic fungus, Microsporum gypseum, from two sites in the base camp occupied by men and by skuas. Trichophyton terrestre was isolated from a site in which people worked and through which penguins and skuas passed.The most widespread fungal species were members of the genus Chrysosporium. Some of these species were isolated but not identified and this part of the study was still be completed.Another significant finding was the absence of fungi in one sample, while in another the widespread and abundant growth in all the seeded dishes of a single species of Chrysosporium.Other species in genera of general diffusion in many environments were also isolated : Aspergillus spp., Malbranchea sp., Mycelia sterilia spp., Paecilomyces sp., Penicillium spp. and Scopulariopsis spp.     

Side effects of propiconazole (tilt 250 ECTM) on non-target soil fungi in a field trial compared with natural stress effects

The present study was performed as a dose-response field experiment using a trade marked formulation of the ergosterol biosynthesis inhibiting fungicide, propiconazole, applied at the recommended and ten times the recommended application rates. The soil dilution plate method was used to isolate fungi from 0–1 and 1–2 cm soil depth. Soil samples were taken 10 times during the period from May 22 to August 11, 1986. The numbers of yeasts and filamentous fungi were enumerated, the latter includingCladosporium andPenicillium, which were also enumerated separately. The fluctuations in fungal occurrence due to the propiconazole treatment were smaller than seasonal fluctuations, these most likely being caused by variations in the soil matric potential and by soil invasion of phyllosphere fungi. Fungicide treatment had significant inhibitory effects on the filamentous fungi, especially on theCladosporium, whereas no significant effects were found on the yeasts and onPenicillium spp. From an ecotoxicological point of view, it is important that the effects were considerably delayed, with respect to the time of fungicide application.     

The diversity,distribution, and pathogenic potential of cultivable fungi present in rocks from the South Shetlands archipelago,Maritime Antarctica

We studied the molecular taxonomy and diversity of cultivable rock fungi from Antarctic islands. From 50 rock samples, 386 fungal isolates were obtained and identified as 33 taxa of 20 genera. The genera Cladophialophora, Cladosporium, Cyphellophora, Eichleriella, Paracladophialophora, and Penicillium displayed the highest densities. Ecological diversity indices showed that the fungal assemblages are diverse and rich with low dominance. The genera Cladophialophora, Cladosporium, and Penicillium showed a broad distribution from rocks of the various islands. One hundred and fifty-nine fungi, grown at 37 °C, were identified as Penicillium chrysogenum, Fusarium sp., and Rhodotorula mucilaginosa. One hundred and three fungi displayed haemolytic activity, 81 produced proteinase, 9 produced phospholipase, and 25 presented dimorphism and a spore diameter ≤ 4 µm. The Antarctic Peninsula region appears to be under the effects of global climate changes, which may expose and accelerate the rock’s weathering processes, and expose and release cryptic fungi and other microbes, especially those with innate pathogenic potential, previously arrested in rocks. Consequently, these rocks and their particles may represent a vehicle for the dispersal of microbial propagules, including those able to spread pathogens, along, across, and out of Antarctica.

     

Growth promotion ability of zoysiagrass rhizosphere fungi in consecutive plantings of wheat and soybean

Several isolates ofPhoma sp., certain nonsporulating fungi, as well asPenicillium andTrichoderma, all isolated from zoysiagrass rhizosphere, promoted growth of wheat and soybean under greenhouse conditions. However, the ability of these rhizosphere fungi to enhance plant growth varied with the crop tested. For example, most of the fungi effectively promoted the growth of wheat, whereas only a few fungi were effective on soybean. In consecutive plantings of wheat and soybean grown in soil previously infested with these zoysiagrass rhizosphere fungi, the growth promotion ability of the fungi was lowered. However, addition of fresh potting medium appeared to restore their growth-promotive effects. It appears that the activation of plant growth-promoting fungi in soil might depend on the availability of organic substrates to colonize, as evidenced by the promotion of plant growth.     

Dominant fungi in the rhizosphere of established tea bushes and their interaction with the dominant bacteria under in situ conditions

Species of Penicillium and Trichoderma were found to dominate the rhizosphere of established tea bushes in a detailed study conducted from various tea growing locations in India. Penicillium erythromellis, P. janthinellum, P. raistrickii, Trichoderma pseudokoningii and T. koningii were found to be closely associated with tea roots. While seasonal fluctuation was observed in the case of Penicillium spp., the population of Trichoderma spp. showed less variation during the year. Both species were sensitive to low temperatures. In general, fungi associated with the tea rhizosphere were found to prefer a mesophillic temperature range (15 °C to 35 °C). The dominant species of Penicillium and Trichoderma also exhibited tolerance to lower temperatures, i.e., 5 to 10 °C on agar plates. Most fungi were able to grow in a wide range of pH (4 to 12). Lowering of soil pH in the rhizosphere of tea bushes was positively correlated with the age of the bush and may have affected the development of a specific microbial community in the rhizosphere.The populations of Penicillium and Trichoderma species were inversely correlated with the populations of two most dominant rhizosphere bacteria, Bacillus subtilis and B. mycoides. Both Bacillus species have been shown to have antagonistic activity against these two fungi under in vitro conditions. The present study demonstrates the existence of a similar antagonism under in situ conditions in the rhizosphere of established tea bushes.     

The fungal flora of soft fruits in relation to storage and spoilage

The fungal population of freshly harvested strawberries, raspberries and blackberries was studied throughout the fruiting seasons and the relative importance of fungi responsible for spoilage of stored fruit from different harvest dates was assessed. Botrytis cinerea, Cladosporium spp., Penicillium spp., Aureobasidium pullulans and Mucor spp. were consistently present on all three fruits while Colletotrichum gloeosporioides and Didymella applanata were prevalent on raspberries only and Epicoccum purpurascens and Alternaria spp. on blackberries only. Botrytis cinerea and Mucor mucedo were the predominant spoilage organisms of all three fruits, although the relative importance of the two fungi changed as the season progressed, especially for strawberries. Rhizopus stolonifer, Cladosporium spp., Penicillium spp. and Colletotrichum gloeosporioides were only of minor importance as spoilage organisms.     

Further study on seasonal fluctuations of Egyptian soil fungi

The seasonal fluctuations of fungi were studied in 72 soil samples collected at 10-day intervals between January 1972 and December 1973. The richest periods in the fungal population were January, March and September–December 1972, and April, May, September, November and December 1973. The poorest months were consistently June and July of 1972 and 1973 and August 1973 which are all summer months. Thirty-nine genera were isolated of which Aspergillus, Penicillium, Fusarium, Mucor, Rhizopus and Humicola were of high seasonal occurrence. Seven genera were of moderate occurrence and these were Cochliobolus,Stachybotrys, Paecilomyces, Cunninghamella, Myrothecium, Chaetomium and Sepedonium. The remaining genera were of low or rare seasonal occurrence. Aspergillus showed its highest prevalence during the periods May-September 1972 and April-August 1973. Twenty-four species of Aspergillus in addition to two varieties of A. nidulans were isolated, of which A. niger, A. fumigatus, A. terreus, A. nidulans and A. sydowii were dominant. Thirty species of Penicillium were identified, of which P. notatum, P. funiculosum and P. chrysogenum were of high seasonal occurrence. Penicillium predominated during winter and spring months. Fusarium showed its highest percentage populations during the periods February, March, April, October, November and December 1972 and February, August, September, October and November 1973. Four species of Mucor were recorded of which M. racemosus was the commonest; and its highest percentage populations were recorded in November 1972; and February, March and November 1973 which are moderate temperature months. Rhizopus was represented by two species of which R. nigricans was of high seasonal occurrence. Three species of Humicola were isolated of which H. grisea was the most common.     

Role of opportunistic fungi in ocular infections in Nigeria

The importance of opportunistic fungal pathogens in causing ocular infections is emphasized. A study was conducted over a period of 4 years (1974–1977) to investigate the role of opportunistic fungi in causing mycotic keratitis and to elucidate certain aspects of epidemiology of this disease in Nigeria. Fifty-nine cases of corneal ulcers of suspected mycotic etiology were investigated. Fungal etiology was confirmed in 42 of these cases. The predominant etiological agent was Fusarium solani in 14 cases (33.33%) followed by Penicillium citrinum in 8 cases (19.04%) and Aspergillus fumigatus in 5 cases (11.90%). The yeasts were responsible for only 3 cases (7.14%) i.e. one each caused by Candida albicans, C. parapsilosis and C. guilliermondii. Among the remaining 12 cases, one was caused by F. moniliforme, 3 by A. flavus, 2 each by A. niger, Penicillium expansum and Penicillium sp., and one each by Cladosporium cladosporioides and Cladosporium sp. The clinical features of the cases are briefly described.The incidence of mycotic keratitis in relation to sex, age, occupation, trauma and other factors has been analysed. Corneal trauma appeared to be an important predisposing factor as 27 (67.28%) of the patients gave a history of injuries to the eye. Notably, a large number of patients were farmers and trauma was most often from palm tree leaf, thorn, kernel or other plant objects. Topical application of corticosteroids or broad spectrum antibiotics did not seem to play an important role in the etiology of keratomycosis. Cases were recorded throughout the year although the number of cases was higher in the months of March –May, and November–December than that during the rest of the year.The isolates of the causative agents were studied in detail for their morphological and cultural characters. The isolates of F. solani grew well at 37°C and survived at 40°C for more than 3 weeks. In vitro drug sensitivity tests indicated good antifungal activity of pimaricin and econazole for F. solani, clotrimazole and econazole for Aspergillus fumigatus, A. flavus and Penicillium citrinum, and 5-fluorocytosine for Candida spp.Investigations on the incidence of fungi in normal healthy eyes of 450 persons comprising 204 adults and 246 children yielded 204 isolates belonging to 21 genera of fungi. Cladosporium was most frequent (12.88%) followed by Penicillium (10.22%) and Aspergillus (6.66%). Another important fungus was Fusarium represented by 10 isolates, viz. 4 of F. solani, 2 of F. moniliforme, 1 of F. exysporum, and 3 of Fusarium sp. The yeasts were represented by two isolates each of Candida tropicalis, C. pseudotropicalis, C. krusei, Trichosporon sp and Cryptococcus albidus, and one of Candida guilliermondii. Successive culturing of fungi from normal eyes in a small group indicated that fungi occur in the outer eye generally as transients.The epidemiology of mycotic keratitis has been discussed in relation to the present findings and in comparison with observations of other investigators.     

Comparison of methods for isolation of dematiaceous fungi from nature

Direct plating and animal inoculation techniques were compared for effectiveness in isolating dematiaceous fungi from nature. The direct plating technique involved comparison of aqueous and mineral oil extraction of the samples with subsequent plating on Mycobiotic and Sabhi agar. Twenty four different organisms were recovered from 19 samples using both extraction procedures and both media. Dematiaceous fungi isolated by direct plating were Alternaria alternata, Cladosporium spp., Exophiala jeanselmei, Wangiella dermatitidis and 6 unidentified organisms. Direct plating resulted in more isolations of dematiaceous fungi partly because of the frequent isolations of A. alternata and W. dermatitidis. Both more and a larger variety of organisms were recovered on Mycobiotic than on Sabhi agar. The aqueous extraction of samples resulted in more direct plating isolations of fungi than oil extraction.Only dematiaceous fungi were isolated with the animal inoculation techniques. Fungi isolated from hamsters included Cladosporium spp., Exophiala spinifera, Phialophora verrucosa, Rhinocladiella sp. and 3 unidentified organisms. Fungi isolated by the mouse inoculation technique included Bispora betulina, Cladosporium spp., W. dermatitidis and 1 unidentified organism. In general there was variation in the types of organisms isolated from the same samples depending on the isolation procedure used.     

The effect of fumigants on soil recolonization in the glasshouse by organisms colonizing the spermosphere

Germinating turnip seeds were used as baits to measure changes in colonizing floras of the spermosphere in glasshouse soil boxes following fumigation. The spermosphere mycoflora of the untreated soil was always dominated by Fusarium, Pythium, and Gliocladium spp. Methyl bromide, chloropicrin, and MBC₃₃ (a 67:33 mixture of methyl bromide and chloropicrin), applied in polyethylene bags at a rate of 2·5 ml/cubic foot of soil, greatly reduced colonization by Fusarium and Pythium spp. for 120 days. Fungi and actinomycetes recolonizing treated soils were more active than in untreated soils, and each fumigant induced a characteristic recolonization pattern. The spermosphere of methyl bromide-treated soil was initially dominated by actinomycetes and later by Penicillium spp. In chloropicrin-treated soil, Trichoderma and later Penicillium spp. dominated, and in soil treated with MBC ₃₃, Penicillium and Trichoderma spp. were co-dominant. Dilution plates, made at the same time from the same soil, indicated a close correlation between inoculum density of different fungi in the soil and their inoculum potentials towards the spermosphere.     

Endophytic fungi in leaves of Lycopersicon esculentum Mill

Endophytic fungi were isolated from healthy tomato leaves from field-grown plants. Several surface-sterilization techniques were assayed for removing and killing epiphytes on tomato leaves. Surface-sterilization with an undiluted commercial solution of sodium hypochlorite was employed. To determine the spectrum of endophytes, samples were collected in February 1998 and 1999 from tomato plants (cultivar Tommy) cultivated in the experimental fields of Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Buenos Aires, Argentina. In general, different spectra of species were isolated in 1998 and 1999.Alternaria alternata was the fungus most frequently isolated from tomato leaves in 1999, but it was the second most common species in 1998. In contrast, Colletotrichum gloeosporioides was the fungus most frequently isolated in 1998, but it was not found in 1999. Species of other genera, such as Cladosporium and Penicillium, were isolated in both years.     

Genetic and physiological relatedness of antagonistic Trichoderma isolates against soil borne plant pathogenic fungi

In this study, the in vitro potential of 42 Trichoderma spp. were evaluated against four isolates of soil borne phytopathogenic fungi viz., Rhizoctonia solani, Macrophomina sp., Sclerotium rolfsii and Pythium aphanidermatum in dual culture techniques and through production of volatile and non-volatile inhibitors. In vitro screening results showed that the proportion of isolates with antagonistic activities was highest for the S. rolfsii followed by R. solani, Macrophomina sp. and P. aphanidermatum, respectively. The isolates TNT1, TNP2 and TWP1 showed consistent results in volatile and non-volatile activity in vitro against any of the two pathogens tested. Based on genomic finger prints, potential isolates showed no particular correlation between the origin of the isolates and the Random Amplified Polymorphic DNA (RAPD) groups could not be established. However, the polymorphism shown by the isolates did not correlate to their level of antagonism. Whereas, in physiology studies using BIOLOG (microbial identification system), three groups were formed, one group consists with 14 different Trichoderma species and two groups with two isolates each comprised of only T. koningii and T. viride.