Environmental detection and application of the speciesspecific
primers
The application of the primer sets was demonstrated by air
sampling and environmental detection of Chrysogenum
complex fungi in London and the Underground. 430 Penicillium
isolates collected from air sampling were tested by PCR using
two of the designed primer sets detecting P. chrysogenum or the
‘Fleming species’. Species distributions between locations
were statistically analysed in Microsoft Excel using the Chisquare
test for independence, analysis of variance (ANOVA)
and the TukeyeKramer test, to significance p < 0.05.
Mating-type frequencies observed were tested against the
null hypothesis of a 1:1 ratio using the Chi-square test for
goodness-of-fit, to significance p < 0.05.
Fungal diversity was recorded from DG18 air sample plates
at 9 d by counting total fungal colonies (Fig 1), Penicillium colonies,
Cladosporium colonies, Aspergillus colonies, other genus
colonies and yeast colonies. Genera counts were performed
and repeated by a mycologist and an undergraduate.
Determination of mating type
46 of the isolates collected were screened for mating type
using MAT1-1 (MAT-1-f, MAT-1-r) and MAT1-2 (MAT-2-f,
MAT-2-r) primer sets (Hoff et al. 2008). Following electrophoresis,
isolates were assigned to either mating type if the
expected amplicon band was detected exclusively in one of
the primer sets (Hoff et al. 2008).