(touchdown 72e65 C), followed by a 72 C extension step for
45 s, followed by 28e35 cycles (different between primer sets)
with a constant annealing temperature of 65 C for 30 s and a
final step of 72 C for 4 min. PCR products were subjected to
electrophoresis in 2 % agarose gels.
Penicillium isolates (n ¼ 148) collected through air sampling
in London were tested by PCR using the four designed primer
sets to ascertain primer specificity by observing for overlapping
positives. To further confirm primer sensitivity and
analyse Penicillium diversity, ITS regions from these 148 isolates
were sequenced and assigned to species using the basic
local alignment search tool (BLAST http://blast.ncbi.nlm.nih.
gov/). Primer sets were also tested for efficacy when performing
PCR direct from fungal conidia using an amended
protocol (Aufauvre-Brown et al. 1993). Conidia from sample
isolates were transferred direct into the PCR reactions by
placing a pipette tip briefly in contact with an isolate colony
from an agar plate and dipping into the reaction well. Conidia
were also transferred directly into the PCR reactions from
water backups of stored fungal isolates by the addition of 2 ml
of backup water instead of the isolate DNA extract.