The broad-scale distribution of microfungi in the Windmill Islands region, continental Antarctica

Microfungi were isolated from soils, mosses, algae and lichens in the Windmill Islands region of Antarctica. From a total of 1,228 isolates, 22 genera were identified. The most frequently isolated fungi from mosses were Mycelia sterilia (47% of total isolates), Phoma spp. (18%), Penicillium spp. (11%), Chrysosporium spp. (7%) and Thelebolus microsporus (6%). Mycelia sterilia, Penicillium spp., Mortierella spp., Chrysosporium cf. pannorum and Thelebolus microsporus were also frequently isolated from algae. Fungal distribution and diversity were poor in samples of lichens, compared to samples from mosses and algae. The frequency of occurrence of microfungi was most often associated with strong biotic influence. There was a marked increase in fungal diversity in human-disturbed sites. Twelve taxa were restricted to soils from near the Australian Casey Station, suggesting significant introduction of fungi into this environment by human activities. Away from the station, fungal distribution appeared to be related to substrata and nutrient status rather than dispersal opportunities. Suggestions for future research and the need for constant monitoring to clarify the role of human disturbance on Antarctic fungi are discussed. Received: 1 April 1997 / Accepted: 17 August 1997     

Effects of temperature on growth rates of fungi from subantarctic Macquarie Island and Casey,Antarctica

Summary The linear growth rates of fungal isolates were measured on agar plates at temperatures ranging from 4° to 35°C. Fungi tested included the major fungal colonizers of leaves and litter of the three dominant plant species on subantarctic Macquarie Island, and major fungal species associated with plant and soil communities near Australia's Casey Station on the Antarctic Continent. All fungi grew at 4°C and were classified as psychrotrophs. Maximum growth rates were recorded at temperatures of 10° to 20°C for 13 of the 15 isolates from Macquarie Island and for all six isolates from Casey. Most of the leaf colonizing fungi from Macquarie Island had optimum growth temperatures of 15°C whereas all litter fungi from Macquarie Island and Casey fungi except Thelebolus microsporus had optimum growth temperatures of 20°C or above. Maximum growth of all species was at temperatures above those normally prevailing in their natural environments, with most species growing at 4°C at between 10% and 30% of their maximum rates. However, microclimatic effects may have resulted at times in temperatures near their growth optima. The highest growth rates at 4°C were recorded for Phoma spp. 1 and 2, Phoma exigua and Mortierella gamsii from Macquarie Island and Mortierella sp. 1 from Casey. Thelebolus microsporus and sterile sp. G from Casey also grew relatively fast at 4°C, and these species, and Phoma sp. 3 and Phoma exigua from Macquarie Island had the lowest Q-₁₀ values for the temperature range 4° to 15°C.     

Fungi isolated from Antarctic material

Summary Fungi isolated from samples of soil, penguin, skua and petrel dung and bird feathers in the Victoria Land, Antarctica, from Inexpressible Island to Cape King, were studied. All material was collected in December 1987–January 1988. Fungi occurred prevalently in bird dung and in soil, especially when mosses were present. The main species isolated were: the keratinophilic Chrysosporium verrucosum and Geomyces pannorum var. pannorum, Phoma herbarum and Thelebolus microsporus. A variety of filamentous fungi and yeasts were also encountered in soil, dung and bird feathers samples in different localities: Acremonium strictum, Cladosporium herbarum, Scolecobasidium salinum, Mortierella antarctica, Paecilomyces farinosus, Phialophora fastigiata, the thermophilic Scytalidium thermophile and Thermomyces lanuginosus, Verticillium sp., Mycelia sterilia and Cryptococcus albidus and Torulaspora delbrueckii. Most of the fungal isolates appeared to be cold-tolerant. Results from this study are discussed in conjuction with data from previous Antarctic studies in this area.     

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.     

Microorganisms colonizing plants and soil subjected to different degrees of human activity,including petroleum contamination,in the Vestfold hills and MacRobertson Land,Antarctica

Summary The fungal floras of plant communities and mineral soils were determined at locations both close to and away from sites of human activity. Petroleum contaminated soils and discarded wood which occur near Stations were also studied, the former for bacterial as well as fungal colonization. The fungal floras of uncontaminated natural communities comprised relatively few species, Geomyces pannorum, Phoma herbarum and Thelebolus microsporus being the most common, together with Epicoccum nigrum at Mawson. P. herbarum dominated the fungal floras of mosses at Mossell Lake but E. nigrum was also common in Mawson mossbeds. G. pannorum was widespread and colonized a range of different habitats, particularly in the Vestfold Hills. T. microsporus was also widespread particularly at sites frequented by birds and seals. Phialophora fastigiata was common around the Stations, especially Davis Station, in soils including those contaminated with oil and in wood, and is thought to have been introduced with softwood packing crates. A greater range of taxa including Mortierella, Mucor, Penicillium and Cladosporium spp. was recorded from Mawson Station than from other sites, and this was attributed to the effects of human activity. Few fungi but a range of bacteria were isolated from the petroleum contaminated soils. A high percentage of these soils contained bacteria which could utilize hydrocarbons as a sole carbon source. Some of these bacteria showed a strong degradative potential, namely Flavobacterium spp., Corynebacterium spp., Bacillus spp. and an isolate from the family Enterobacteriaceae. One isolate of Corynebacterium and the Enterobacteriaceae isolate were active hydrocarbon degraders at 1°C. Hormoconis resinae, the imperfect state of Amorphotheca resinae was only isolated from oil spill soils and then only from sites of recent spills. Geomyces pannorum and Thelebolus microsporus were less common in oil contaminated soils than in uncontaminated soils.     

Human hair colonizing fungi in water sediments of India

Out of 144 samples of water sediments, 183 isolates belonging to 9 genera and 22 species were isolated. Fifty-nine isolates of Acremonium, 26 of Chrysosporium indicum, 22 of Chrysosporium keratinophilum, 17 of Malbranchea sp. and 10 of Microsporum gypseum were recovered. Acremonium implicatum, Chrysosporium georgii, Chrysosporium xerophilum and Geomyces pannorum were reported for the first time from India. This revised version was published online in June 2006 with corrections to the Cover Date.     

If you can’t stand the heat,stay out of the city: Thermal reaction norms of chitinolytic fungi in an urban heat island

Elevated soil and air temperatures in urban heat islands have been exerting evolutionary pressure on organisms for decades in some cities. We measured thermal reaction norms (18–26 °C) for growth rate of four species of common chitinolytic fungi from an oak forest in an urban heat island and a corresponding rural area. Urban isolates of Chrysosporium pannorum and Trichoderma koningii grew faster than rural isolates at 26 °C, but grew slower than rural isolates at 18 °C. Urban isolates of Torulomyces lagena and Penicillium bilaii grew as fast or faster than rural isolates at all temperatures. These differences in thermal reaction norms between urban and rural isolates suggest that urbanization has caused both thermal specialization and counter-gradient variation in the fungal community.     

Some environmental factors affect growth and antibiotic production by the mycoparasite Coniothyrium minitans

The effects of temperature and pH on growth and antibiotic production by three isolates of Coniothyrium minitans (Conio, Contans and IVT1), known to produce the macrolide antibiotic macrosphelide A, were examined in modified Czapek Dox broth (MCD). Antibiotic production was determined by incorporating heated (60°C for 5 min) C. minitans spent culture filtrates of MCD (10%, v/v) into potato dextrose broth and assessing the ability of the filtrates to inhibit growth of S. sclerotiorum. All isolates grew over the temperature range of 10–30°C, with the optimum at approximately 15–20°C. Antibiotics were produced by all isolates at 10–30°C. Culture filtrates of MCD from all isolates incorporated into PDB inhibited growth of S. sclerotiorum by >50%, whereas there was a reduction in inhibition at 30°C for Conio and IVT1 but not Contans. All three isolates grew over the pH range of 3–7, with greater biomass production in buffered pH 3–5 than the unbuffered control (pH 4.8) media. Antibiotics were produced by all isolates at pH 3–5. Culture filtrates of MCD from all three isolates grown at pH 3–5 inhibited growth of S. sclerotiorum, with the greatest effect on inhibition observed at pH 3. There were no differences in growth inhibition between isolates at pH 3 and 4, but culture filtrates from Conio grown at pH 5 inhibited S. sclerotiorum more than those of IVT1 grown at the same pH. The significance of these results for biocontrol and optimizing antibiotic production by C. minitans is discussed.     

Damping-off of Some Cucurbitaceous Crops in Saudi Arabia with Reference to Control Methods

Isolation of seed borne fungi from sweet melon (najed and red Queen varieties) and vegetable marrow (squash) using PDA, Plain agar media and blotters revealed the presence of Alternaria alternata (Fr.) Keissler, Fusarium semitectum var,majus from Najed melon, A. alternata (Fr.) Keissler, F. sambucinum Fuckel from Red Queen melon and A. chlamydospora Mouchacca, Cephalosporium sp., and F. oxysporum schlecht from squash. Pathogenicity tests showed, that all these fungi were highly pathogenic on their respective hosts. The optimum temperature for its growth ranged from 25–30°C and the optimum pH was 6.0. In pot trials, seed dressing with Banrot, Bavistin and Topsin-M at the rate of 4 g/kg seed was superior in controlling the damping-off of melon and squash. These fungicides were effective in inhibiting mycelial growth, spore germination and development of the isolated fungi. Hot water treatment at 55 C/20 min or solar heating (av. 37°C) for 90 min were next to fungicides.     

Change in medium components and colony morphology due to mycelial growth of ectomycorrhizal fungusTricholoma bakamatsutake

Mycelia ofTricholoma bakamatsutake isolate No. 4 grew at temperatures ranging from 10 to 30°C, and the optimum was around 25°C. In well-buffered media of initial pH 5.0 and 6.0, No. 4 mycelia secreted gluconic acid and lowered medium pH. Mycelial growth then accelerated slightly; and with the exhaustion of glucose, growth and secretion of gluconic acid stopped. In 10 different media of initial pH 4.0–7.0, No. 4 mycelia showed higher gluconic acid secretion with higher initial pH. No. 4 mycelial grew best in pH 5.0 media, in which gluconic acid secretion was low. Mycelia of 29 isolates including No. 4 grew better in the media in which less glucose, total carbon and total nitrogen remained, and almost all isolates secreted gluconic acid. Most of the 29 isolates showed irregular colony shapes with rough mycelial fronts, brown pigmentation and aerial hypha on colony surfaces, and brown pigmentation of media under colonies. Dissimilarities were calculated with coded morphological characters on colonies, and similarity between isolates was found not to correlate with proximity of origin. Chlamydospores were observed on every colony of the 29 isolates. Chlamydospores were present on colonies of No. 4, reaching to 2 mm from the mycelial front, where brown pigmentation had not yet developed, and the numbers of chlamydospores incresed with mycelial aging.     

Effect of environmental factors on tenuazonic acid production by Alternaria alternata on soybean-based media

Aims: To determine the effects of water activity (a_W; 0·995–0·90), temperature (5, 18, 25 and 30°C), time of incubation (7–35 days) and their interactions on tenuazonic acid (TA) production on 2% soybean‐based agar by two Alternaria alternata strains isolated from soybean in Argentina. Methods and Results: TA production by two isolates of A. alternata was examined under interacting conditions of a_W, temperature and time of incubation on 2% soybean‐based agar. Maximum TA production was obtained for both strains at 0·98 a_W, but at 30 and 25°C for the strains for RC 21and RC 39, respectively. The toxin concentration varied considerably depending on a_W, temperature, incubation time and strain interactions. TA was produced over the temperature range from 5 to 30°C and a_W range from 0·92 to 0·995, however at 5 and 18°C little TA was produced at a_W below 0·94. Contour maps were developed from these data to identify areas where conditions indicate a significant risk for TA accumulation. Conclusions: The optimum and marginal conditions for TA production by A. alternata on soybean‐based agar were identified. The results indicated that TA production by A. alternata is favoured by different temperatures in different strains. Significance and Impact of the Study: Data obtained provide very useful information for predicting the possible risk factors for TA contamination of soybean as the a_W and temperature range used in this study simulate those occurring during grain ripening. The knowledge of TA production under marginal or sub‐optimal temperature and a_W conditions for growth are relevant as improper storage conditions accompanied by elevated temperature and moisture content in the grain can favour further mycotoxin production and lead to reduction in grain quality.     

Isolation and characterization of novel denitrifying alkalithermophiles, AT-1 and AT-2

Two novel denitrifying alkalithermophilic bacteria, AT-1 and AT-2, were isolated from manure-amended soil. The isolates grew at 35–65°C with an optimum temperature at 50–60°C, and pH 6.5–10.0 with an optimum pH at 9.5. Both isolates were Gram-positive, facultative anaerobic, non-motile rod-shaped bacteria. A phylogenetic analysis based on 16S rRNA sequence data indicated that both AT-1 and AT-2 are members of the genus Anoxybacillus. DNA-DNA hybridization revealed moderate relatedness between AT-1 and AT-2 and one phylogenetically related strain, A. pushchinensis K1 (69.5 and 69.1%, respectively). Comparative analysis of morphology and biochemical characteristics of the two isolates also showed similarity to A. pushchinensis K1. Based on these results, we identified AT-1 and AT-2 as A. pushchinensis. To our knowledge, this is the first report of denitrifying bacterium isolated from alkalithermophilic Anoxybacillus spp.     

Antioxidant enzyme activity of filamentous fungi isolated from Livingston Island, Maritime Antarctica

From 18 soil samples taken in the vicinity of the permanent Bulgarian Antarctic base “St. Kliment Ohridski” (62°38′29″S, 60°21′53″W) on Livingston Island, 109 filamentous fungi were isolated on selective media. The most widespread fungal species were members of the genera Cladosporium, Geomyces, Penicillium and Aspergillus. Other species, already recorded in Antarctic environment, were also isolated: Lecanicillium muscarium, Epicoccum nigrum and Alternaria alternata. Thirty strains demonstrating good growth were screened for antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) that play an important role in the defense of aerobic organisms against oxidative stress, by converting reactive oxygen species into nontoxic molecules. Six of them showed high enzyme activity. The tested strains produced SOD with statistically significant higher activity at 15°C than at 30°C suggesting that this enzyme is cold-active. Such SOD could be useful in medicine and cosmetics. The best producer of cold-active SOD, Aspergillus glaucus 363, cultivated in bioreactors, demonstrated optimal growth temperature at 25°C and maximum enzyme activities at 25 and 30°C for SOD and CAT, respectively. The electrophoretical analysis showed that the fungus possesses Cu/Zn-SOD.     

Characterization of chitinase from Streptomyces luridiscabiei U05 and its antagonist potential against fungal plant pathogens

Streptomyces luridiscabiei U05 was isolated from wheat rhizosphere. It produced chitinase, which showed in vitro antifungal properties. The crude enzyme inhibited the growth of Alternaria alternata, Fusarium oxysporum, F. solani, Botrytis cinerea, F. culmorum and Penicillium verrucosum. The chitinase enzyme of the molecular weight of 45 kDa was purified using affinity chromatography of chitin. Streptomyces luridiscabiei U05 produced different chitinolytic enzymes. The highest enzyme activity was observed with the use of 4‐MU‐(GlcNAc)_, which points to the presence of an β‐N‐acetylhexosaminidase. The optimum activity was obtained at 35–40°C and pH 7–8. The enzyme showed thermostability at 35–40°C during 240 min of preincubation and lost its activity at 50°C and 60°C in 60 min. The chitinase activity from S. luridiscabei U05 was strongly inhibited by Hg²⁺ and Pb²⁺ ions, and sodium dodecyl sulphate (SDS). The Ca²⁺, Cu²⁺ and Mg²⁺ ions stimulated the activity of the enzyme.     

Thermophilic protease-producing Geobacillus from Buranga hot springs in Western Uganda

Two proteolytic thermophilic aerobic bacterial strains, PA-9 and PA-5, were isolated from Buranga hot springs in western Uganda. The cells were rods, approximately 10–12 μm in length and 3 μm in width. Isolate PA-9 grew at between 38°C and 68°C (optimum, 62°C), and PA-5 grew at between 37°C and 72°C (optimum, 60°C). Both isolates grew optimally at pH 7.5–8.5. Their 16S rRNA gene sequences indicated that they belong to the newly described genus Geobacillus. Zymogram analysis of the crude enzyme extracts revealed the presence of two extracellular proteases for isolate PA-5, and at least eight for isolate PA-9. The optimum temperature and pH for casein-degrading activity were 70°C, pH 6.5 for isolate PA-9, but caseinolytic activity could also be observed at 2°C. In the case of isolate PA-5, optimal activity was observed over a temperature and pH range of 50–70°C and pH 5–10, respectively. Received: 26 November 2001 / Accepted: 12 December 2001     

Effect of temperature on the in vitro radial growth of Zoophthora radicans and Pandora blunckii, two co-occurring fungal pathogens of the diamondback moth Plutella xylostella

The effect of four different temperatures (15, 20, 25 and 30°C) on the in vitro growth of 19 isolates of Pandora blunckii and 14 isolates of Zoophthora radicans from Plutella xylostella larvae was investigated. Both species grew more at 20 and 25°C than the other two temperatures. However, Z. radicans grew more than P. blunckii at 20 and 25°C. Within each species there were differences amongst: all isolates regardless of geographical origin, isolates from different countries and isolates from Mexico. No relationship was found between optimal growth temperature and geographical origin. This represents the first report of the relationship between temperature and the in vitro growth of P. blunckii. The ecological role of this large variability amongst isolates within each species is discussed.     

Cellulase activity of some phytopathogenic fungi isolated from diseased leaves of broad bean

Forty-five fungal species and two varieties belonging to the 23 genera were collected from 50 samples of diseased leaves of broad bean collected from Qena Governorate in Egypt on glucose-Czapek’s, dichloran-chloramphenicol-malt extract and dichloran-chloramphenicol-peptone agar at 28 °C. The most common genera were Alternaria, Aspergillus, Cladosporium, Fusarium, Mycosphaerella and Penicillium. The most prevalent species were Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, Cladosporium cladosporioides, Fusarium merismoides, Mycosphaerella tassiana and Penicillium chrysogenum. Among the eight dematiaceous Hyphomycetes phytopathogenic fungi screened for their abilities to produce both exo- and endo-β-1,4-glucanase enzymes (C₁ and C_x), five species had high C₁ enzyme production and two species had high C_x enzyme production. However, two and three species were moderately active in producing C₁ and C_x enzymes, respectively. The remaining species had low production of both C₁ and C_x enzymes. The highest cellulase activity was recorded by Alternaria citri and Cochliobolus spicifer for C₁ and by A alternata and A. citri for C_x enzyme. Maximum production of C₁ enzyme by A. citri and C. spicifer was obtained after six days of incubation at 30 °C with an initial pH of 6 in a culture medium containing lactose and calcium nitrate as the carbon and nitrogen sources, respectively. The highest C_x enzyme production was by A. alternata and A. citri,which was recorded after eight days of incubation at 30 °C with an initial pH of 6 in a culture medium containing carboxymethyl cellulose and sodium or calcium nitrate as the carbon and nitrogen sources, respectively.     

Microscopic and macroscopic study of the interaction betweenAlternaria alternata (Fr.) Keissler andNigrospora oryzae (Berk. & Broome) Petch.

Light Microscopy and Cryo-Scanning Electron Microscopy techniques were used to analyse the interaction betweenAlternaria alternata andNigrospora oryzae at different temperatures (15 and 25°C) and water activities (0.85, 0.90, 0.95, 0.98 and 0.995). Each interaction was given a numerical value to obtain the Index of Dominance (I) based on the variations observed in fungus growth when the environmental conditions changed. For a better understanding of the process, each species was studied individually anysing the effects of abiotic and biotic factors on their growth. In the tests performed, none of the two fungus species analysed was dominant over the other since both species presented mutual intermingling both in Rice Extract agar and in rice grains and no interaction between hyphae and the reproductive structures was observed.Alternaria alternata andN. oryzae presented their highest growth both individually and dually at 0.995 water activity and 25°CAlternaria alternata sporulated at all temperatures and water activity values, except at 0.85, whereasN. oryzae sporulated only at 0.98 and 0.995 at 25°C, presenting no changes as the strains interacted. Finally, temperature and water activity significantly affected fungal growth.     

Isolation and Identification of Ruminal Methanogens from Grazing Cattle

To obtain information on the diversity of ruminal methanogens in grazing animals, three ruminal methanogens from grazing cattle were characterized and identified. Two of the isolates were rod-shaped, with one staining Gram-positive and being non-motile (BRM9), and the other (BRM16) staining Gram-negative and being motile. These isolates grew only on H₂/CO₂ and formate, and optimally at 38°C and pH 6.5–7.0. The third isolate (CM1) was non-motile, pseudosarcina-shaped, and grew on H₂/CO₂, acetate, and methyl-containing compounds, with optimal growth at 40°C and pH 6.5. DNA was prepared from the three isolates, and their 16S rRNA genes were sequenced. Phenotypic data and comparisons of nearly complete 16S rDNA sequences showed that BRM9, BRM16, and CM1 are strains of Methanobacterium formicicum, Methanomicrobium mobile, and Methanosarcina barkeri respectively. To the best of our knowledge, this is the first information on ruminal methanogens in cattle maintained under grazing management. Received: 26 October 1999 / Accepted: 22 November 1999     

Alternaria on cruciferous plants. 4.Alternaria species on seed of some cruciferous crops and their pathogenicity

The incidence ofAlternaria spp. on seed samples of cruciferous vegetable crops was surveyed between 1990 and 1992. Some commercial seed lots of crucifers which are commonly grown in Japan were infested withAlternaria species. ThreeAlternaria species were encountered on the seed samples ofBrassica campestris, B. orelacea, andRaphanus sativus. The most frequently detected species wereA. japonica andA. alternata onB. campestris, A. brassicicola onB. oleracea, andA. japonica andA. alternata onR. sativus, respectively.Alternaria brassicae was not detected in this study.Alternaria brassicicola isolates from these crops produced necrotic lesions on all of the crucifer seedlings inoculated, whileA. japonica induced different reactions in different plants or plant parts depending on isolates used in inoculation tests. In contrast, most isolates ofA. alternata could not produce necrotic lesions on foliage leaves of crucifers inoculated, although some of them produced clear lesions only on cotyledons.Alternaria alternata associated with these cruciferous crop seeds was considered to be an oppotunistic parasite of these crops.