Effects of water activity and temperature on the survival of Aspergillus carbonarius spores in vitro.
OBJECTIVE
To determine the effect of water activity (a(w)) and temperature on the survival of Aspergillus carbonarius spores.


RESULTS
Spores of A. carbonarius were dried onto filter membranes. These filters were held at 1.0, 0.9, 0.8, 0.6 and 0.4 a(w) and at 1, 15, 25 and 37 degrees C for up to 618 d. At intervals, spores were recovered from filters and assessed for viability by enumeration on dichloran rose bengal chloramphenicol agar. Survival and subsequent growth of spores was prolonged at low temperatures and at a(w) below 0.6. Above 15 degrees C, 0.6-0.9 a(w) were often more deleterious than 1.0. However, at 1 degrees C and 1.0 a(w), spores lost viability more rapidly than at lower a(w).


CONCLUSIONS
Increased incidence of black Aspergillus spp. in dry soils and from grapes in dry conditions may result partly from prolonged survival of spores.


CONCLUSIONS
Delineating the direct effect of a(w) and temperature on survival of A. carbonarius spores may aid in understanding the incidence of this ochratoxin A-producing species in vineyard soils and on grapes.
Leong
S L
SL
CSIRO Food Science Australia, North Ryde, NSW, Australia.
Hocking
A D
AD
Scott
E S
ES
D001230:Aspergillus / Q000254:growth & development*; D009793:Ochratoxins / Q000096:biosynthesis; D013172:Spores, Fungal / Q000502:physiology*; D013696:Temperature; D027843:Vitis / Q000382:microbiology; D014867:Water
D009793:Ochratoxins; D014867:Water; C025589:ochratoxin A