Aspergillus species producing ochratoxin A: isolation from vineyard soils and infection of Semillon bunches in Australia.
OBJECTIVE
The incidence of toxigenicity among Australian isolates of Aspergillus niger and Aspergillus carbonarius was assessed. Aspergillus rot and concomitant production of ochratoxin A (OA) in bunches inoculated with A. carbonarius were also investigated.


RESULTS
Aspergillus niger and A. carbonarius were isolated from vineyard soils. Aspergillus niger was more widespread than A. carbonarius, and two restriction fragment length polymorphism types of A. niger, N and T, were present. Three of 113 A. niger isolates and all 33 A. carbonarius isolates produced OA. Aspergillus carbonarius was inoculated onto Semillon bunches with and without damage in the month before harvest. Damaged berries at greater than 12.3 (o) Bx were particularly susceptible to Aspergillus rot and production of OA, which was concentrated in severely mouldy berries.


CONCLUSIONS
OA in Australian grapes results mainly from infection of berries by A. carbonarius. It is concentrated in discoloured, shrivelled berries. The potential for Aspergillus rot and OA production appears to commence after veraison and increase with berry damage and ripeness.


CONCLUSIONS
Minimizing damage to grapes between veraison and harvest significantly reduces Aspergillus rot and OA formation. Monitoring the extent of Aspergillus rot in bunches infected with toxigenic Aspergillus spp. may give some indication of OA contamination.
Leong
S L
SL
CSIRO Food Science Australia, North Ryde, NSW, Australia.
Hocking
A D
AD
Scott
E S
ES
D001230:Aspergillus / Q000302:isolation & purification* / Q000378:metabolism; D001234:Aspergillus niger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001315:Australia; D002273:Carcinogens / Q000032:analysis; D005516:Food Microbiology; D005638:Fruit / Q000378:metabolism / Q000382:microbiology*; D009183:Mycotoxins / Q000032:analysis*; D009793:Ochratoxins / Q000032:analysis*; D010935:Plant Diseases / Q000382:microbiology*; D012150:Polymorphism, Restriction Fragment Length; D012988:Soil Microbiology; D013172:Spores, Fungal / Q000302:isolation & purification / Q000378:metabolism; D027843:Vitis / Q000378:metabolism / Q000382:microbiology; D014920:Wine / Q000382:microbiology
D002273:Carcinogens; D009183:Mycotoxins; D009793:Ochratoxins; C025589:ochratoxin A