Nutrition of Phialophora verrucosa A126

Summary The quantity of growth and type of sporulation is reported, using 19 carbon and 44 nitrogen sources; but the initial aim of inducton of fertile perithecia inP. verrucosa A126, by altering the amount and types of nutrients, was not realized.     

Phialophora parasitica, an emerging pathogen

Monoconidial cultures derived from 12 clinical and environmental isolates of Phialophora parasitica were compared with respect to morphologic and physiologic characteristics and response to antifungal agents. No yeast cells were seen in 1- and 3-week-old slide culture preparations. Also, not all of the distinguishing characteristics of this species were displayed by all isolates on all media examined. Although the isolates grew on Sabouraud agar with chloramphenicol and cycloheximide, some inhibition was observed. All cultures were strongly urease-positive and hydrolyzed casein and starch; most decomposed tyrosine but not gelatin. All but one environmental isolate grew well at both 23 and 37 degrees C, but none grew at 40 degrees C. In the sensitivity testing the isolates did not vary much in their response to each drug, although some anomalies were observed. Amphotericin B and miconazole had minimum inhibitory concentrations in the low sensitivity range (2.0-8.0 and 2.5-10 micrograms m-1 respectively), for most isolates, and most isolates were resistant to both 5-fluorocytosine and ketoconazole. Limited observations were made on three other Phialophora species which might be confused with P. parasitica.     

Studies on preservative tolerant Phialophora species

Phialophora species are shown to possess a variable capacity for growth on either copper, arsenic or copper-chrome-arsenic (CCA) supplemented laboratory media. The most copper tolerant species. Phialophora sp. A, P. malorum and P. mutabilis, were also the most arsenic resistant. Fine structural studies have shown intra- and to a lesser extent extracellular localization of copper which may provide a means of tolerating high external copper levels under culture conditions. Wood decay experiments have shown Phialophora spp. to have a good capacity to degrade K33 treated birch after 7·5 months but not pine, despite colonization. The most important wood degrading Phialophora were also the more copper/arsenic resistant species although non-tolerant species were also able to degrade treated birch. A comparison between the extreme copper levels tolerated by selected species with the amount of copper in treated wood may suggest that only sub-toxic levels may be obtained, levels which may not require special detoxification mechanisms for either colonization or decay in wood. In this respect, factors other than toxicity, particularly the nature of the substrate (e.g. lignin type and level) and reaction with CCA and ammoniacal-copper during treatment may be of greater significance.     

Predisposition of Aster to Phialophora wilt

The susceptibility of Aster novi-belgii to infection by the vascular wilt pathogen Phialophora asteris varied according to the growing conditions to which the host was subjected before inoculation. Relatively low air temperature, high soil moisture, and soil nutrients rich in potassium or phosphorus were pre-inoculation conditions in which Aster became relatively susceptible. Increased resistance was favoured by growing plants at relatively high air temperatures, low soil moisture, and soil nutrients rich in nitrogen or calcium but low in potassium or phosphorus prior to inoculation.     

Budding in the Dimorphic Fungus Phialophora dermatitidis

Ultrastructural comparisons of yeast and hyphal bud formation in Phialophora dermatitidis reveal that bud initiation is characterized by a blastic rupture of the outer portion of the yeast or hyphal wall and the emergence of a bud protuberance through the resulting opening. The wall of the emerging bud is continuous, with only an inner wall layer of the parental yeast or hypha. The outer, ruptured portion of the parental wall typically forms a collar around the constricted emergence region of the developing bud. The cytoplasm within the very young emerging bud invariably contains a small number of membrane-bound vesicles. The septum formed between the daughter bud and the parental yeast or hypha is a complete septum devoid of a septal pore, septal pore plug, or any associated Woronin bodies characteristic of simple septa of the moniliform or true hyphae. These observations suggest that yeast bud formation and lateral hyphal bud formation in the dimorphic fungus P. dermatitidis involve a growth process which occurs identically in both the yeast and mold phase of this human pathogenic organism.     

Lipases of Fonsecaea pedrosoi and Phialophora verrucosa

Lipase activity was demonstrable titrimetrically in the culture filtrates of Fonsecaea pedrosoi and Phialophora verrucosa on the 6th day of incubation reaching a peak on the 15th and 12th days respectively for the two fungi. Purified lipases of F. pedrosoi and P. verrucosa, with specific activities of 36.0 and 39.4 fold increase respectively, were obtained by cold acetone extraction, gel filtration followed by ion exchange chromatography. The lipases had the same optimum pH (5.5) and temperature (35° C). The molecular weights of the lipases of F. pedrosoi and P. verrucosa, estimated by gel filtration on Sephadex G-100, were 25000 and 20000, respectively and the enzymes showed broad susbstrate specificity. The possible role of lipase in the pathogenesis of infection caused by the fungi is discussed.     

Conjugation in the Dimorphic Chromomycosis Fungus Phialophora dermatitidis

Phase-contrast microscope observations of the dimorphic fungus Phialophora dermatitidis revealed that thick-walled yeasts often tended to form aggregates and then to conjugate. Fusions were also observed among hyphae derived from the thick-walled yeasts.     

Phialophora parasitica, Causal Agent of Cherry Dieback

Structure-activity relationships of the phytotoxins stemphyloxin I and II from Stemphylium botryosum f. sp. lycopersici were investigated by quantitative comparison of their biological activity with chemically related phytotoxins from Phoma betae, betaenones A, B and C. Phytotoxicity was estimated by inhibition of incorporation of¹⁴C-leucine into proteins of exponentially growing tomato cells. The values of 50 % inhibition for stemphyloxin I and II and for betaenones A, B and C were 0.075, 16, 55, 350 and 1 μM respectively. The β-ketoaldehyde moiety appeared to be essential in, conferring biological activity and its toxicity was influenced by its spatial orientation. The presence of an hydroxyl group in stemphyloxin I and II enhanced activity in comparison with the respective compounds betaenones C and A which lack this group.     

Cellulose degradation and cellulase formation by Phialophora malorum

The formation of cellulases and -glucosidase and their location in the fungus Phialophora malorum was studied on some different carbon sources. The cellulases were found to be partly cell-free and partly cell-bound during growth on cellulose and carboxymethyl-cellulose. Glucose and cellobiose repressed the cellulase formation but a low carboxymethylcellulase activity was measurable on the glucose-grown mycelium. The unicellular stage did not appear to grow on carboxymethyl-cellulose or cellulose, but mycelium was formed on these carbon sources.     

贵州省瓶霉属二新种(英文)

在对贵州省土壤暗色丝孢真菌进行调查研究中,分离获得2个瓶霉属新种:土壤瓶霉Phialophora subterranea和光滑瓶霉P.levis,对二者进行了详细的描述并绘图。研究菌株的干制培养物及活菌种均存放在贵州大学植物病理学标本室(HGUP)。     

Recalcitrant Primary Subcutaneous Phaeohyphomycosis Due to Phialophora verrucosa

Phialophora verrucosa has rarely been reported for causing phaeohyphomycosis, which tends to occur in immunocompromised individuals. The case of primary subcutaneous phaeohyphomycosis due to P. verrucosa in an otherwise healthy Chinese female is presented. The girl presented with asymptomatic skin lesions when she was only 16 year old. Histological examinations revealed multiple dematiceous hyphael elements in the dermis and subcutaneous tissues. Fungal cultures were identified as P. verrucosa repeatedly based on the morphological features and confirmed by the internal transcribed spacer region nucleotide sequencing. The infection was so extremely recalcitrant that prolonged systemic antifungal regimens for 12 years revealed limited effect. The skin lesions slowly progressed and caused marked disfigurement despite the encouraging results of in vitro susceptibility. However, no relevant side effects have been reported in the course, and the patient gave birth to a healthy baby while under the maintenance treatment of itraconazole and terbinafine. This case is special in terms of the early onset, the rare clinical aspect of the pathogen, the discrepancy between in vitro and in vivo antifungal activities and especially the prolonged and recalcitrant course in such an otherwise healthy host.     

Details of the fungistatic effect of Phialophora cinerescens]

We have previously isolated two chlorinated antibiotics from Phialophora asteris and P. asteris f. sp. helianthi, vascular pathogens on plants. P. cinerescens, pathogen on carnation, also presents a fungitoxic activity but the nature of the antibiotic compound is still unknown. We point out that this activity can be lost by sectorial variations on the growing margin and that the antibiotic product shows a striking photolability.