| Phialophora fastigiata | |
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Scientific classification | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Eurotiomycetes |
| Order: | Chaetothyriales |
| Family: | Herpotrichiellaceae |
| Genus: | Phialophora |
| Species: | P. fastigiata |
| Binomial name | |
| Phialophora fastigiata (Lagerb. & Melin) Conant (1937) | |
| Synonyms | |
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Phialophora fastigiata is amitosporic,[1] saprophytic fungus commonly found in soil,[2] and on wood,[3] and wood-pulp.[4] This species was initially placed in the genusCadophora but was later transferred to the genusPhialophora based on morphological and growth characteristics.[5] In culture,P. fastigiata produces olive-brown, velvety colonies.[3] The fungus is recognizable microscopically due to the presence of distinctive, funnel-shaped cuffs (collarettes) encircling the tips ofphialides that bear slimyconidia.[2] The fungus is often implicated insoft-rot wood decay due to its ability to degradelignin,[6]cellulose andpectin.[2] It has also been reported to causeblue staining of wood and wood pulp.[4]
Phialophora fastigiata was originally described in 1928 asCadophora fastigiata by Lagerberg and Melin, who erected the genusCadophora to accommodateC. fastigiata.[5] In 1937, Conant compared eight species ofCadophora withPhialophora verrucosa and determined that they belonged to the same genus. As such, seven species ofCadophora, includingC. fastigiata were transferred to the genusPhialophora.[5] Although later examination of theinternal transcribed spacers ofribosomal DNA (rDNA) genes inCadophora melinii andP. fastigiata showed morphological similarity, the colony morphology of the two species is distinctive.[7]
Macroscopically,P. fastigiata colonies reach 2.3–2.5 cm (0.91–0.98 in) in diameter after being grown at 20 °C on malt extract agar for 10 days.[2] They exhibit an olive-brown[2] or reddish-brown[3] velvety appearance, and grow with a border ofhyaline (glassy)mycelium.[3] Aerial mycelium form a floccose (fluffy) greyish-brown turf 1.0-6.5mm high, and produce rope-like strands towards the centre of the colony.[5] Although isolates usually grow uniformly, slight differences in colour, numbers ofconidiophores and numbers of aerial mycelium have been observed.[8]
Phialophora fastigiata are microscopically recognized by the production of light brown, flask-shapedphialides[2] that are produced laterally onhyphae[9] and produce funnel-shaped collarettes.[2] In Petri dish cultures, the fungus tends to develop hyphal strands that are 3-4μm in diameter and show cell-wall thickening with age.[3] Slimy conidia are produced in clumps at the apex of phialides,[5] and are oval shaped (ovoid) to button shaped (ellipsoidal) with a pinched base.[2] The conidia initially exhibit ahyaline (unpigmented) appearance, but turn light brown with age.[2]
Isolates ofP. fastigiata are able to grow at temperatures ranging from 3 °C to 35 °C, with an optimum temperature range of 20 °C–25 °C and pH range between 4–9.[8] Extracts of water and acetone frombalsam fir,black spruce,white spruce andred spruce have been shown to stimulate the growth of the fungus in culture.[8] The presence ofbiotin also increases the growth of this fungus[8] and extracts of ammonium tartrate increase mycelium production.[10] This saprophytic fungus[5] is able to gain energy from decaying organic matter, and is able to utilizeasparagine andpotassium nitrate as sources of nitrogen, as well as L-arabinose as a source of carbon.[10]
Phialophora fastigiata is able to produce a variety of degradation enzymes, includingpectinase,amylase,xylanase,cellulase andmannanase,[2] which allow it to cause wood decay[11] and post-harvest rot.[12] Although there has been no investigation into the management ofP. fastigiata, the fungus is known to be susceptible to theantimicrobial activity ofethanolic extract fromHalacsya sendtneri,[13] a flowering plant in the familyBoraginaceae. The fungus is also susceptible toantimycins produced byStreptomyces species.[14] Conversely,P. fastigiata exhibits antimicrobial activity againstGaeumannomyces graminis var tritici, a plant pathogen that causestake-all disease inwheat.[15]
Phialophora fastigiata is commonly isolated from soil and wood.[2] The earliest reports of the fungus came from countries and regions rich in wood, such asSweden,Norway andCanada.[3] It was later isolated from a spruce plantation in Norway[16] and has been found to grow on wood pulp in Sweden.[4] It is also the most abundant species found in slime from paper mills inNew Brunswick andNewfoundland,[8] and has been isolated from wheat-field soils inWestern Australia.[17]
The fungus is psychrotolerant (able to grow at low temperatures), and has been isolated from soil,[18] straw and wood in theRoss Sea region ofAntarctica.[19] It has also been isolated from the water-saturated wood ofBetula pendula trees,[20] dialysis water, municipal drinking water,[21] groundwater, surface water, and tap water.[22]
Phialophora fastigiata is asoft rot fungus that has been found to widen cavities inbirch andScots pine sapwood by increasing growth at the hyphal tip and secreting lignolytic enzymes (involved in the degradation oflignin) from the hyphal surface.[6] The fungus can also cause cavities in wood and plants via an erosion-type attack.[23] The ability of the fungus to degrade the wood ofPopulus tremuloides (trembling aspen) has been noted to limit the sale of aspen, which represents 54% of commercialtimber.[24]
P. fastigiata also commonly causes blue staining of wood. It has been found to grow on wood pulp with a greyish-green tinge, causing the wood pulp to appear blue[4] and is one of the most common species of fungi associated with discoloredxylem in the stems ofB. pendula.[25] Degradation and discoloration of wood byP. fastigiata affect the production quality of pulp and paper.[24]
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