Advances in Food Mycology

Black Aspergillus Species in Australian Vineyards 161
0.2 ml/min) and monitoring the natural fluorescence of OA at 435 nm
after excitation at 385 nm (Shimadzu, RF-10AXL). Sample injections
were performed using a Shimadzu SIL-10Advp autosampler, and the
typical injection volume was 30 µl. OA in the wine extracts was quantified
by comparison with a calibration curve. Typical recoveries
ranged from 80-100%. The results presented have not been corrected
for recovery.
3. RESULTS AND DISCUSSION
3.1. Aspergillus carbonarius in the Vineyard
Environment
Counts of A. carbonarius were high in soil and in vine trash on soil
and relatively low on other substrates (Table 2). Hence, soil is likely to
be the primary source of A. carbonarius in vineyards.
In the four vineyards surveyed, soil beneath vines contained more
A. carbonarius than soil between rows (P < 0.05, Figure 2). This
association is likely to be due to damaged and dead berries falling
onto the soil and providing a sugar-rich medium for the growth of
indigenous saprophytic Aspergillus species. The concentration of
A. carbonarius propagules was highest at the surface of soil, where
this debris is found, and decreased deeper within the soil profile of
an untilled vineyard (Figure 3). The vineyard in which the soil profile
was regularly disturbed by tilling contained a higher concentration
of A. carbonarius in the soil than vineyards in which the soil was
less disturbed (P < 0.05, Figure 2). In vineyards with minimal tillage,
A. carbonarius may be one member of a complex and stable microbial
community associated with the cover crop and other flora on the
soil surface. One potential effect of regular tillage is to allow
the increase of a dominant species (Marfenina and Mirchink, 1989).
Table 2. Aspergillus carbonarius on vineyard materials. Results expressed as cfu/ml
surface wash unless otherwise indicated.
Substrate 2000-01 2001-02 2002-03
Canes (dead) 8 1 not recorded
Vine bark 31 9 not recorded
Bunch remnants 47 15 not recorded
Cover trash (dead) 8 10 2
Vine trash on soil 669 45 20
Soil (cfu/g) 4,987 1,219 1,342