Browsing by Author "Frazer, Schale"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Characterisation of stachybotrys chartarum from water damaged buildings
    (Cranfield University, 2011) Frazer, Schale; Aldred, David
    Fungal contaminated buildings and related adverse human health implications have long been a topical issue throughout the world and concern is mounting with regards to the presence of more toxigenic fungi found in buildings and the associated health risks. These risks are compounded when homes are affected by water damage as a result of water intrusion problems, in particular flooding. With the ever changing climate and unpredictable weather conditions the frequency of flash flooding has increased in recent years and is set to increase and subsequently more homes will inevitably be effected by mould contamination. The present study initially aimed to determine the types of fungi commonly detected in buildings in the United Kingdom with varied levels of water intrusion problems via a small survey using various sampling techniques and particularly aimed to determine the conditions by which growth of the toxigenic fungi Stachybotrys chartarum could occur. Penicillium, Cladosporium and Aspergillus species were the most commonly detected fungi in buildings with relatively moderate levels of water intrusion problems; Stacybotrys chartarum was only detected in building with more severe water intrusion problems. Cont/d.
  • Thumbnail Image
    ItemOpen Access
    Impact of environmental factors on growth and satratoxin G production by strains of Stachybotrys chartarum
    (Wageningen Academic Publishers, 2012-12-31T00:00:00Z) Frazer, Schale; Pestka, James J.; Kim, Jae-Kyung; Medina-Vayá, Ángel; Aldred, David; Magan, Naresh
    The black mould Stachybotrys chartarum and its mycotoxins have been linked to damp building-associated illnesses. The objective of this study was to determine the effects of water availability (water activity, aw) and temperature on growth and production of satratoxin G (SG) by a macrocyclic trichothecene-producing strain (IBT 7711) and non-producing strain (IBT 1495) of S. chartarum. Growth studies were carried out on potato dextrose agar modified with glycerol to 0.995-0.92 aw at 10-37 °C. Growth extension was measured and the cultures were extracted after 10 days and a competitive enzyme-linked immunosorbent assay (ELISA) method used to quantify the SG content. Growth was optimal at 25 to 30 °C at 0.995 aw, but this was modified to 0.98 aw at 30 °C for both strains (1.4- 1.6 mm/day, respectively). The ELISA method revealed that, in contrast to growth, SG production was maximal at 20 °C with highest production at 0.98 aw (approximately 250 μg/g mycelia). When water was freely available (0.995 aw), SG was maximally produced at 15 °C and decreased as temperature was increased. Interestingly, the strain classified as a non-toxigenic produced very low amounts of SG (<1.6 μg/g mycelia) that were maximal at 25 °C and 0.98 aw. Contour maps for growth and SG production were developed from these data sets. These data have shown, for the first time, that growth and SG production profiles are very different in relation to key environmental conditions in the indoor environment. This will be very useful in practically determining the risk from exposure to S. chartarum and its toxins in the built envi
  • Thumbnail Image
    ItemOpen Access
    The influence of water activity and temperature on germination, growth and sporulation of stachybotrys chartarum strains
    (Springer Science Business Media, 2011-07-01T00:00:00Z) Frazer, Schale; Magan, Naresh; Aldred, David
    The objectives were to determine theinfluence of water activity (aw, 0.997-0.92) andtemperature (10-37C) and their interactions onconidial germination, mycelial growth and sporulationof two strains of Stachybotrys chartarum in vitroon a potato dextrose medium. Studies were carriedout by modifying the medium with glycerol andeither spread plating with conidia to evaluate germinationand germ tube extension or centrally inoculatingtreatment media for measuring mycelialgrowth rates and harvesting whole colonies fordetermining sporulation. Overall, germination ofconidia was significantly influenced by aw andtemperature and was fastest at 0.997-0.98 aw between15 and 30C with complete germination within 24 h.Germ tube extension was found to be most rapid atsimilar aw levels and 25-30C. Mycelial growth ratesof both strains were optimal at 0.997 aw between 25and 30C, with very little growth at 37C. Sporulationwas optimum at 30C at 0.997 aw. However,under drier conditions, this was optimum at 25C.This shows that there are differences in the ranges ofaw x temperature for germination and growth and forsporulation. This may help in understanding the roleof this fungal species in damp buildings and conditionsunder which immune-compromised patientsmay be at risk when exposed to such contaminantsin the indoor air environment.